EN-304-617.md

18. Charging state changes debounced
19. No historical battery data exposed
20. API surface minimized for privacy

**Pass Criteria**: Battery data quantized AND updates throttled AND rate limiting enforced AND no detailed analytics exposed

**Fail Criteria**: Precise battery data OR no throttling OR no rate limiting OR historical data exposed

**Evidence**: Battery level precision tests, timing quantization measurements, update frequency analysis, rate limiting verification, cross-origin test results, privacy analysis reports

**References**:

- Battery Status API: https://www.w3.org/TR/battery-status/
- Battery API Privacy Concerns: https://www.w3.org/TR/battery-status/#privacy-considerations
- Web API Privacy: https://www.w3.org/TR/fingerprinting-guidance/
- Chrome Battery Status: https://chromestatus.com/feature/4537134732017664

### Assessment: SYS-REQ-20 (Hardware resource limits)

**Reference**: SYS-REQ-20 - Browser shall enforce resource limits to prevent excessive consumption of CPU, memory, and system resources

**Given**: A conformant browser with SYS-1 or higher capability

**Task**: Unrestricted hardware resource consumption enables denial-of-service attacks that freeze browsers, crash systems, drain battery, or make devices unusable through memory exhaustion, CPU monopolization, or GPU resource depletion. Malicious scripts with infinite loops or excessive allocations can render browsers unresponsive. Per-origin resource limits, background throttling, script timeouts, and memory quotas prevent resource-based DoS attacks while maintaining browser and system responsiveness.

**Verification**:

1. Create test page that attempts to allocate excessive memory and verify limits
2. Test CPU-intensive operations and verify throttling or limits applied
3. Monitor browser resource usage with intensive JavaScript loops
4. Test WebWorker resource limits and verify isolation
5. Verify background tab resource throttling is active
6. Test WebAssembly memory limits and verify enforcement
7. Monitor GPU memory usage and verify limits on WebGL contexts
8. Test that runaway scripts trigger timeout warnings or termination
9. Verify resource limits apply per-origin or per-process
10. Test that browser remains responsive under resource pressure
11. Memory allocation limits prevent excessive consumption
12. CPU-intensive operations are throttled
13. Background tabs have reduced resource quotas
14. WebWorkers have separate resource limits
15. WebAssembly memory is bounded and enforced
16. GPU memory limits prevent resource exhaustion
17. Script timeouts prevent infinite loops
18. Resource limits are per-origin or per-process
19. Browser UI remains responsive under load
20. User can terminate runaway processes/tabs

**Pass Criteria**: Memory limits enforced AND CPU throttling active AND background throttling works AND script timeouts prevent hangs

**Fail Criteria**: No memory limits OR no CPU throttling OR background tabs not throttled OR scripts can hang indefinitely

**Evidence**: Memory allocation test results, CPU usage graphs showing throttling, background tab resource measurements, WebWorker limit tests, script timeout logs, browser responsiveness tests

**References**:

- WebAssembly Memory: https://webassembly.github.io/spec/core/syntax/modules.html#memories
- Script Execution Limits: https://html.spec.whatwg.org/multipage/webappapis.html#long-tasks
- Firefox Process Limits: https://wiki.mozilla.org/Project_Fission

### Assessment: SYS-REQ-21 (Memory isolation enforcement)

**Reference**: SYS-REQ-21 - Browser shall enforce memory isolation between processes to prevent cross-process memory access

**Given**: A conformant browser with SYS-1 or higher capability

**Task**: Memory isolation failures enable cross-process data theft, Spectre-class attacks to read arbitrary memory, privilege escalation through memory corruption, and exploitation of use-after-free vulnerabilities. Without ASLR, SharedArrayBuffer restrictions, and Spectre mitigations, attackers can reliably exploit memory vulnerabilities to breach process boundaries. Memory isolation with ASLR, cross-origin isolation requirements, memory zeroing, and hardware protections prevents cross-process memory attacks.

**Verification**:

1. Launch browser with multiple processes and identify their memory spaces
2. Use memory analysis tools to verify process memory isolation (valgrind, windbg, lldb)
3. Test that renderer processes cannot access browser process memory
4. Verify SharedArrayBuffer requires cross-origin isolation
5. Test that different origins cannot share memory without explicit mechanisms
6. Verify ASLR (Address Space Layout Randomization) is enabled
7. Test that Spectre mitigations prevent speculative execution memory leaks
8. Verify memory is zeroed when deallocated and reused
9. Test that memory dumps do not leak data between processes
10. Verify hardware memory protection (NX, DEP) is enabled
11. Each process has isolated virtual memory space
12. Renderer processes cannot read browser process memory
13. SharedArrayBuffer requires explicit CORS headers
14. ASLR randomizes memory addresses per process
15. Spectre/Meltdown mitigations prevent side-channel leaks
16. Memory is zeroed on deallocation
17. No cross-process memory leaks detectable
18. Hardware NX/DEP prevents code execution in data pages
19. Process crashes don't leak memory to other processes
20. Memory forensics shows proper isolation

**Pass Criteria**: Process memory isolated AND SharedArrayBuffer restricted AND ASLR enabled AND Spectre mitigations active

**Fail Criteria**: Cross-process memory access possible OR SharedArrayBuffer unrestricted OR no ASLR OR Spectre vulnerable

**Evidence**: Memory map analysis, process memory dumps, SharedArrayBuffer test results, ASLR verification, Spectre/Meltdown mitigation tests, memory leak detection reports

**References**:

- SharedArrayBuffer Security: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer#security_requirements
- Spectre Mitigations: https://www.chromium.org/Home/chromium-security/ssca/
- ASLR: https://en.wikipedia.org/wiki/Address_space_layout_randomization
- Site Isolation: https://www.chromium.org/Home/chromium-security/site-isolation/

### Assessment: SYS-REQ-22 (CPU resource quotas)

**Reference**: SYS-REQ-22 - Browser shall enforce CPU resource quotas to prevent any single origin from monopolizing processor resources

**Given**: A conformant browser with SYS-1 or higher capability

**Task**: CPU resource monopolization by malicious scripts enables cryptojacking attacks that steal processing power for cryptocurrency mining, denial-of-service through CPU exhaustion, battery drain on mobile devices, and system slowdowns affecting user productivity. Background tabs consuming CPU enable covert mining operations. CPU quotas with background throttling, timer throttling, requestAnimationFrame suspension, and per-origin limits prevent CPU monopolization while maintaining responsiveness for foreground content.

**Verification**:

1. Create test page with intensive CPU computation (tight loop or crypto operations)
2. Monitor CPU usage per process using OS tools (top, Task Manager, Activity Monitor)
3. Test that background tabs have reduced CPU quotas
4. Verify WebWorker CPU usage is counted toward origin quota
5. Test CPU throttling for invisible pages (display:none, zero opacity)
6. Verify timer throttling for background processes (setTimeout, setInterval)
7. Test that requestAnimationFrame is paused for background tabs
8. Monitor overall system CPU and verify browser doesn't exceed limits
9. Test that users can identify and terminate high-CPU tabs
10. Verify CPU priority scheduling favors foreground/visible content
11. Background tabs throttled to <1% CPU typically
12. Foreground tabs have priority CPU access
13. WebWorker CPU usage tracked per origin
14. Invisible elements have reduced CPU quotas
15. Timers throttled in background (1Hz or lower)
16. requestAnimationFrame paused when not visible
17. Browser task manager shows per-tab CPU usage
18. Users can terminate high-CPU tabs easily
19. System CPU usage remains reasonable under load
20. CPU scheduling prioritizes user-visible content

**Pass Criteria**: Background throttling active AND timers throttled AND rAF paused AND user can terminate high-CPU tabs

**Fail Criteria**: No background throttling OR timers not throttled OR rAF active in background OR no termination controls

**Evidence**: CPU usage graphs per tab, background throttling measurements, timer frequency tests, rAF execution logs, task manager screenshots, system CPU monitoring

**References**:

- Page Lifecycle API: https://developer.chrome.com/blog/page-lifecycle-api/
- Timer Throttling: https://developer.mozilla.org/en-US/docs/Web/API/setTimeout#throttling
- requestAnimationFrame: https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame
- Firefox Process Priority: https://wiki.mozilla.org/Project_Fission#Process_prioritization

### Assessment: SYS-REQ-23 (Network bandwidth limits)

**Reference**: SYS-REQ-23 - Browser shall enforce network bandwidth limits to prevent excessive network resource consumption

**Given**: A conformant browser with SYS-1 or higher capability

**Task**: Uncontrolled network resource consumption enables bandwidth exhaustion attacks, connection pool depletion preventing legitimate requests, network-based denial-of-service, and excessive data usage on metered connections. Malicious origins opening unlimited connections can monopolize network resources. Per-origin connection limits, HTTP/2 stream limits, WebSocket quotas, and background deprioritization prevent network resource abuse while enabling efficient multiplexing and user control.

**Verification**:

1. Create test page that attempts high-volume network requests
2. Monitor network usage per origin using browser DevTools Network panel
3. Test connection limits per origin (typically 6-10 connections)
4. Verify HTTP/2 and HTTP/3 multiplexing limits
5. Test bandwidth throttling for background tabs
6. Verify WebSocket connection limits per origin
7. Test that large downloads can be paused or cancelled
8. Monitor overall browser network usage and verify limits
9. Test that fetch() requests respect connection pooling limits
10. Verify users can identify and control network-heavy tabs
11. Connection limits enforced per origin (6-10 connections)
12. HTTP/2 stream limits enforced (max concurrent streams)
13. Background tabs have reduced network priority
14. WebSocket connections limited per origin
15. Large transfers pausable and cancellable
16. Connection pooling prevents excessive sockets
17. Browser task manager shows network usage per tab
18. Network throttling options available in DevTools
19. Overall browser network reasonable under load
20. Users can control network-heavy operations

**Pass Criteria**: Connection limits enforced AND background deprioritization AND WebSocket limits AND user controls available

**Fail Criteria**: Unlimited connections OR no background priority OR unlimited WebSockets OR no user controls

**Evidence**: Network connection graphs, DevTools Network panel screenshots, connection limit test results, WebSocket limit verification, background priority measurements, task manager network stats

**References**:

- HTTP Connection Management: https://developer.mozilla.org/en-US/docs/Web/HTTP/Connection_management_in_HTTP_1.x
- HTTP/2 Specification: https://httpwg.org/specs/rfc7540.html
- Chrome Network Throttling: https://developer.chrome.com/docs/devtools/network/reference/#throttling
- WebSocket Limits: https://datatracker.ietf.org/doc/html/rfc6455
- Firefox Network Priority: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Priority

### Assessment: SYS-REQ-24 (Storage quota enforcement)

**Reference**: SYS-REQ-24 - Browser shall enforce storage quotas for origin-scoped storage mechanisms including IndexedDB, Cache API, and local storage

**Given**: A conformant browser with SYS-1 or higher capability

**Task**: Unrestricted storage enables disk space exhaustion attacks, storage-based denial-of-service, tracking through persistent data storage, and system instability from full disks. Malicious origins filling storage prevent legitimate applications from functioning. Per-origin storage quotas, persistent storage permissions, QuotaExceededError enforcement, and separate incognito limits prevent storage abuse while enabling adequate space for web applications and maintaining system stability.

**Verification**:

1. Test StorageManager.estimate() to query available storage quota
2. Attempt to exceed storage quota using IndexedDB and verify QuotaExceededError
3. Test localStorage quota limits (typically 5-10MB)
4. Verify Cache API respects storage quota
5. Test that storage quota is per-origin and isolated
6. Verify persistent storage requires explicit user permission
7. Test that storage usage is accurately reported in browser settings
8. Verify storage can be cleared per-origin by user
9. Test that incognito/private mode has separate, limited storage
10. Verify storage quota warnings or prompts for large allocations
11. Storage quotas enforced per-origin (typically 50-100MB default)
12. StorageManager API accurately reports usage and quota
13. QuotaExceededError thrown when limits reached
14. localStorage limited to 5-10MB per origin
15. Cache API storage counted toward quota
16. Persistent storage requires user permission
17. Browser settings show per-origin storage usage
18. Users can clear storage per-origin
19. Incognito mode has separate, limited quota
20. Large storage requests trigger user prompts

**Pass Criteria**: Quotas enforced per-origin AND QuotaExceededError thrown AND persistent storage requires permission AND user controls available

**Fail Criteria**: No quota enforcement OR errors not thrown OR persistent storage auto-granted OR no user controls

**Evidence**: StorageManager.estimate() results, QuotaExceededError screenshots, localStorage limit tests, Cache API quota tests, browser settings storage UI, incognito mode quota verification

**References**:

- Storage API: https://storage.spec.whatwg.org/
- StorageManager: https://developer.mozilla.org/en-US/docs/Web/API/StorageManager
- IndexedDB Quota: https://www.w3.org/TR/IndexedDB/#dom-idbdatabase-transaction
- Chrome Storage Quotas: https://web.dev/articles/storage-for-the-web
- Firefox Storage Limits: https://developer.mozilla.org/en-US/docs/Web/API/Storage_API/Storage_quotas_and_eviction_criteria

### Assessment: SYS-REQ-25 (Process priority management)

**Reference**: SYS-REQ-25 - Browser shall implement process priority management to ensure responsive user experience and fair resource allocation

**Given**: A conformant browser with SYS-1 or higher capability

**Task**: Without process priority management, background tabs can monopolize CPU resources causing foreground tab lag, audio playback in background can be interrupted unfairly, and browser responsiveness suffers from equal treatment of all processes. Priority inversion where background processes starve foreground operations degrades user experience. Dynamic process priority management ensuring foreground preference, audio continuity, and fair scheduling prevents resource contention while maintaining responsive user interaction.

**Verification**:

1. Launch browser with multiple tabs and identify process priorities using OS tools
2. Verify foreground tab processes have higher priority than background
3. Test that audio-playing tabs maintain elevated priority
4. Verify visible tabs have higher priority than hidden tabs
5. Test process priority changes when switching tabs
6. Monitor CPU scheduling and verify foreground processes get preference
7. Test that extension processes have appropriate priority
8. Verify utility processes (network, GPU) have appropriate priority
9. Test that frozen background tabs have lowest priority
10. Verify process priorities don't allow starvation
11. Foreground tabs run at higher OS process priority
12. Background tabs run at reduced priority (low or below normal)
13. Audio-playing tabs maintain adequate priority
14. Priority changes dynamically when switching tabs
15. CPU scheduler gives preference to high-priority processes
16. Extension processes have appropriate priority
17. Utility processes prioritized by criticality
18. Frozen tabs have lowest priority
19. No process starvation occurs
20. User-facing processes most responsive

**Pass Criteria**: Foreground tabs high priority AND background tabs low priority AND dynamic priority adjustment AND no starvation

**Fail Criteria**: All same priority OR no background reduction OR static priorities OR starvation occurs

**Evidence**: Process priority listings (nice values, Windows priority classes), CPU scheduling analysis, tab switching priority changes, audio playback priority verification, process responsiveness measurements

**References**:

- Chrome Process Model: https://www.chromium.org/developers/design-documents/multi-process-architecture/
- Linux Process Priority: https://man7.org/linux/man-pages/man2/nice.2.html
- Windows Process Priority: https://docs.microsoft.com/en-us/windows/win32/procthread/scheduling-priorities
- Page Lifecycle: https://developer.chrome.com/blog/page-lifecycle-api/

### Assessment: SYS-REQ-26 (Sandbox escape prevention)

**Reference**: SYS-REQ-26 - Browser shall implement multiple layers of defense to prevent sandbox escape attacks

**Given**: A conformant browser with SYS-1 or higher capability

**Task**: Sandbox escapes are high-severity vulnerabilities that allow compromised renderers to break containment and gain full system access, enabling malware installation, data exfiltration, and system compromise. Single-layer sandboxes are vulnerable to bypass through exploitation of implementation bugs or kernel vulnerabilities. Defense-in-depth with multiple sandbox layers, syscall filtering, IPC validation, kernel exploit mitigations, and continuous fuzzing prevents sandbox escapes even when individual defenses are bypassed.

**Verification**:

1. Review browser's sandbox architecture documentation and layers of defense
2. Test syscall filtering using strace/dtruss to verify blocked calls
3. Attempt known sandbox escape techniques and verify they're mitigated
4. Verify IPC validation prevents malformed messages from escaping sandbox
5. Test that renderer processes cannot ptrace or debug other processes
6. Verify memory corruption in renderer doesn't allow privilege escalation
7. Test that GPU process sandbox is separate from renderer sandbox
8. Verify kernel exploit mitigations (SMEP, SMAP, KPTI) are active
9. Test fuzzing results for sandbox bypass vulnerabilities
10. Verify security updates address discovered sandbox escapes
11. Multiple sandbox layers (syscall filter, namespace isolation, capability dropping)
12. Dangerous syscalls blocked (execve, ptrace, mount, etc.)
13. IPC messages validated in broker process
14. Process debugging APIs blocked
15. Memory corruption contained within sandbox
16. GPU sandbox independent from renderer
17. Kernel exploit mitigations active (SMEP, SMAP, KPTI)
18. Regular fuzzing for sandbox bypasses
19. Security updates address known escapes
20. Defense-in-depth architecture

**Pass Criteria**: Multiple sandbox layers AND syscall filtering AND IPC validation AND kernel mitigations active

**Fail Criteria**: Single layer only OR syscalls not filtered OR IPC not validated OR kernel mitigations missing

**Evidence**: Sandbox architecture documentation, syscall trace logs, sandbox escape test results, IPC validation logs, kernel mitigation verification, fuzzing reports, security update changelogs

**References**:

- Chromium Sandbox: https://chromium.googlesource.com/chromium/src/+/master/docs/design/sandbox.md
- Linux Namespace Isolation: https://man7.org/linux/man-pages/man7/namespaces.7.html
- Seccomp BPF: https://www.kernel.org/doc/html/latest/userspace-api/seccomp_filter.html
- SMEP and SMAP: https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance.html
- Project Zero Sandbox Escapes: https://googleprojectzero.blogspot.com/

### Assessment: SYS-REQ-27 (Speculative execution mitigations)

**Reference**: SYS-REQ-27 - Browser shall implement mitigations for speculative execution vulnerabilities including Spectre and Meltdown

**Given**: A conformant browser with SYS-1 or higher capability

**Task**: Spectre and Meltdown enable attackers to exploit speculative execution in modern CPUs to read arbitrary memory across security boundaries, including passwords, encryption keys, and cross-origin data. Without mitigations, malicious JavaScript can use timing side channels to leak sensitive data from other processes or origins. Site Isolation, timer quantization, SharedArrayBuffer restrictions, CORB, and COOP/COEP headers prevent speculative execution attacks by ensuring cross-origin data never shares address space.

**Verification**:

1. Verify Site Isolation is enabled using chrome://process-internals or equivalent
2. Test that high-resolution timers are reduced precision (performance.now() granularity)
3. Verify SharedArrayBuffer requires cross-origin isolation headers
4. Test that cross-origin data is not accessible in same process
5. Verify CORB (Cross-Origin Read Blocking) prevents sensitive data leaks
6. Test that speculative execution cannot leak cross-origin data
7. Verify process-per-site-instance isolation for sensitive origins
8. Test that COOP/COEP headers enable process isolation
9. Verify kernel page-table isolation (KPTI) is active on system
10. Test that Spectre PoC exploits are mitigated
11. Site Isolation active for all sites or at least sensitive origins
12. Timer precision reduced to 100 microseconds or coarser
13. SharedArrayBuffer requires COOP+COEP headers
14. Cross-origin data in separate processes
15. CORB blocks cross-origin reads of sensitive MIME types
16. Spectre PoC exploits fail to leak data
17. Process-per-site-instance for banks, login pages
18. COOP/COEP enable strict process isolation
19. KPTI active on vulnerable systems
20. Regular updates address new speculative execution vulnerabilities

**Pass Criteria**: Site Isolation enabled AND timer precision reduced AND SharedArrayBuffer restricted AND CORB active

**Fail Criteria**: No Site Isolation OR high-precision timers OR SharedArrayBuffer unrestricted OR CORB disabled

**Evidence**: Site Isolation status screenshots, timer precision measurements, SharedArrayBuffer tests with/without headers, CORB blocking logs, Spectre PoC test results, KPTI verification

**References**:

- Spectre Mitigations: https://www.chromium.org/Home/chromium-security/ssca/
- Site Isolation: https://www.chromium.org/Home/chromium-security/site-isolation/
- SharedArrayBuffer: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer#security_requirements
- CORB: https://chromium.googlesource.com/chromium/src/+/master/services/network/cross_origin_read_blocking_explainer.md
- Spectre Attack: https://spectreattack.com/

### Assessment: SYS-REQ-28 (Side-channel attack mitigations)

**Reference**: SYS-REQ-28 - Browser shall implement mitigations for side-channel attacks including timing attacks, cache attacks, and fingerprinting

**Given**: A conformant browser with SYS-1 or higher capability

**Task**: Side-channel attacks exploit timing differences, cache behavior, rendering performance, and other observable effects to infer sensitive information like user history, cross-origin data, or cryptographic keys. High-precision timers enable microarchitectural attacks, CSS :visited timing leaks browsing history, and cache timing reveals cross-origin content. Timer quantization, process isolation for cache partitioning, cross-origin timing sanitization, and fingerprinting surface minimization prevent side-channel information leakage.

**Verification**:

1. Test timer precision reduction (performance.now(), Date.now()) to verify quantization
2. Verify SharedArrayBuffer is disabled or requires isolation headers
3. Test that cache timing attacks are mitigated through process isolation
4. Verify rendering timing cannot leak cross-origin information
5. Test that event loop timing is not exploitable for side channels
6. Verify CSS timing attacks are mitigated (e.g., :visited link timing)
7. Test that network timing doesn't leak cross-origin data
8. Verify SVG filter timing attacks are prevented
9. Test that WebGL cannot be used for timing side channels
10. Verify fingerprinting surfaces are minimized or permissions-gated
11. Timer precision reduced (100 microseconds or coarser)
12. SharedArrayBuffer requires COOP+COEP isolation
13. Process isolation prevents cache-based side channels
14. Rendering timing doesn't leak cross-origin data
15. Event loop timing not exploitable
16. :visited link styling restricted to prevent timing attacks
17. Network timing (Resource Timing API) sanitized for cross-origin
18. SVG filter timing attacks mitigated
19. WebGL timing attacks prevented through various restrictions
20. Fingerprinting APIs require permission or are restricted

**Pass Criteria**: Timer quantization active AND SharedArrayBuffer isolated AND process isolation prevents cache attacks AND cross-origin timing sanitized

**Fail Criteria**: High-precision timers OR SharedArrayBuffer unrestricted OR no cache isolation OR timing leaks exist

**Evidence**: Timer precision tests, SharedArrayBuffer isolation verification, cache timing attack tests, cross-origin timing measurements, fingerprinting surface analysis, side-channel PoC test results

**References**:

- Web Platform Security: https://www.w3.org/TR/fingerprinting-guidance/
- Timing Attacks: https://www.w3.org/TR/hr-time-2/#clock-resolution
- CSS :visited Privacy: https://developer.mozilla.org/en-US/docs/Web/CSS/Privacy_and_the_:visited_selector
- Resource Timing: https://www.w3.org/TR/resource-timing-2/
- Fingerprinting Resistance: https://brave.com/privacy-updates/3-fingerprint-randomization/

### Assessment: SYS-REQ-29 (Hardware token security)

**Reference**: SYS-REQ-29 - Browser shall implement secure access controls for hardware security tokens and authenticators (WebAuthn)

**Given**: A conformant browser with SYS-1 or higher capability and WebAuthn support

**Task**: Hardware security tokens provide strong authentication but require secure browser integration to prevent phishing, credential theft, and authenticator cloning attacks. Without HTTPS requirements and origin binding, attackers could steal credentials or use fake authenticators. User verification and presence requirements prevent remote attacks. HTTPS enforcement, origin-bound credentials, attestation validation, user presence requirements, and extension isolation ensure WebAuthn security while enabling passwordless authentication.

**Verification**:

1. Test WebAuthn registration with hardware security key (e.g., YubiKey)
2. Verify registration requires HTTPS context (except localhost)
3. Test that user verification (PIN/biometric) is enforced when required
4. Verify authenticator attestation is validated correctly
5. Test that credentials are origin-bound and not accessible cross-origin
6. Verify user presence is required (physical touch/button press)
7. Test that CTAP2 protocol is properly implemented for FIDO2 devices
8. Verify browser extensions cannot intercept WebAuthn operations
9. Test that authenticator selection respects user choice
10. Verify platform authenticators (Touch ID, Windows Hello) are isolated
11. WebAuthn requires secure context (HTTPS or localhost)
12. User verification enforced when requested by relying party
13. Attestation validation prevents cloned/fake authenticators
14. Credentials strictly origin-bound (site isolation)
15. User presence required (physical interaction)
16. CTAP2 protocol correctly implemented
17. Extensions cannot intercept or modify WebAuthn
18. Users choose authenticator from picker
19. Platform authenticators use OS-level secure enclaves
20. Private keys never accessible to JavaScript

**Pass Criteria**: HTTPS required AND user verification enforced AND origin-bound credentials AND user presence required

**Fail Criteria**: HTTP allowed OR no user verification OR cross-origin access OR no user presence

**Evidence**: WebAuthn registration screenshots, attestation validation logs, cross-origin test results, user presence verification, CTAP2 protocol traces, platform authenticator tests

**References**:

- WebAuthn Specification: https://www.w3.org/TR/webauthn-2/
- FIDO2 CTAP: https://fidoalliance.org/specs/fido-v2.0-ps-20190130/fido-client-to-authenticator-protocol-v2.0-ps-20190130.html
- WebAuthn Security: https://www.w3.org/TR/webauthn-2/#sctn-security-considerations
- FIDO Security Reference: https://fidoalliance.org/specifications/

### Assessment: SYS-REQ-30 (Accessibility API security)

**Reference**: SYS-REQ-30 - Browser shall implement security controls for accessibility APIs to prevent information leakage and unauthorized access

**Given**: A conformant browser with SYS-1 or higher capability

**Task**: Accessibility APIs expose detailed page structure, content, and user interactions to assistive technologies, creating vectors for information leakage, fingerprinting, unauthorized content scraping, and privacy violations if not properly controlled. Malicious software masquerading as assistive technology could harvest passwords, track user actions, or extract sensitive content. OS-level permission requirements, sensitive data masking, cross-origin restrictions, and remote access authentication prevent accessibility API abuse while serving users with disabilities.

**Verification**:

1. Enable OS accessibility features (screen reader, voice control)
2. Verify browser exposes accessibility tree to authorized assistive technology only
3. Test that accessibility API requires user opt-in or OS-level permission
4. Verify accessibility tree doesn't leak sensitive data (passwords, hidden content)
5. Test that cross-origin content has restricted accessibility exposure
6. Verify accessibility events don't leak timing or user interaction information
7. Test that remote accessibility access (enterprise tools) requires authentication
8. Verify accessibility API cannot be abused for fingerprinting
9. Test that ARIA attributes don't leak security-sensitive information
10. Verify screen reader access is logged for security auditing
11. Accessibility API access requires OS-level permission
12. Only authorized assistive technology can access accessibility tree
13. Sensitive content (passwords) properly masked in accessibility tree
14. Cross-origin content has limited accessibility exposure
15. Accessibility events sanitized to prevent leakage
16. Remote accessibility requires authentication
17. Accessibility API cannot be used for fingerprinting
18. ARIA attributes don't leak sensitive information
19. Accessibility access auditable
20. Browser communicates securely with assistive technology

**Pass Criteria**: OS permission required AND sensitive data masked AND cross-origin limited AND remote access authenticated

**Fail Criteria**: No permission required OR passwords exposed OR cross-origin fully accessible OR remote access unauthenticated

**Evidence**: Accessibility permission flows, accessibility tree dumps showing masking, cross-origin accessibility tests, remote access authentication verification, fingerprinting tests, audit logs

**References**:

- WAI-ARIA: https://www.w3.org/TR/wai-aria-1.2/
- Accessibility Object Model: https://wicg.github.io/aom/spec/
- Chrome Accessibility: https://www.chromium.org/developers/design-documents/accessibility/
- macOS Accessibility: https://developer.apple.com/documentation/accessibility
- Windows Accessibility: https://docs.microsoft.com/en-us/windows/win32/winauto/entry-uiauto-win32

### Assessment: SYS-REQ-31 (Native messaging restrictions)

**Reference**: SYS-REQ-31 - Browser shall enforce security restrictions on native messaging between extensions and native applications

**Given**: A conformant browser with SYS-1 and EXT-1 or higher capability

**Task**: Native messaging bridges the browser extension sandbox and native applications, creating risks of sandbox escape, privilege escalation, arbitrary code execution, and malware installation if not properly controlled. Malicious extensions could exploit native messaging to execute system commands, access sensitive files, or install malware. Manifest permissions, host registration, extension ID validation, message validation, and privilege limitation prevent native messaging abuse while enabling legitimate browser-native integration.

**Verification**:

1. Create test extension with nativeMessaging permission
2. Verify extension requires explicit permission declaration in manifest
3. Test that native messaging host is registered with browser
4. Verify only explicitly allowed extensions can communicate with native host
5. Test that native messaging requires user installation of native component
6. Verify message validation occurs on browser side
7. Test that native host process runs with limited privileges
8. Verify native messaging cannot bypass extension sandbox
9. Test that uninstalling extension terminates native messaging connections
10. Verify enterprise policies can restrict or acceptlist native messaging
11. nativeMessaging permission required in manifest
12. Native host is registered in browser's native messaging directory
13. Only permitted extensions (by ID) can connect to host
14. User should manually install native host application
15. Messages validated by browser before passing to/from host
16. Native host runs with limited OS privileges
17. Extension sandbox not bypassed via native messaging
18. Extension uninstall terminates native connections
19. Enterprise policies can control native messaging
20. Native host path validation prevents arbitrary execution

**Pass Criteria**: Manifest permission required AND host registration required AND extension ID validation AND user installs host

**Fail Criteria**: No permission required OR no host registration OR any extension can connect OR automatic host installation

**Evidence**: Extension manifest examples, native host registration files, permission validation tests, message validation logs, privilege analysis of native host, enterprise policy tests

**References**:

- Chrome Native Messaging: https://developer.chrome.com/docs/extensions/develop/concepts/native-messaging
- Firefox Native Messaging: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Native_messaging

### Assessment: SYS-REQ-32 (Host OS integration security)

**Reference**: SYS-REQ-32 - Browser shall securely integrate with host operating system features while maintaining sandbox boundaries and security isolation

**Given**: A conformant browser with SYS-1 or higher capability

**Task**: Host OS integration provides essential functionality but creates attack surfaces for credential theft, certificate validation bypass, policy evasion, and privilege escalation if not properly secured. Insecure credential access exposes passwords, certificate store bypass enables MITM attacks, and policy violations undermine enterprise security. Secure IPC for credentials, OS certificate store usage, file association validation, policy compliance, and update signature verification maintain security boundaries while enabling OS integration.

**Verification**:

1. Test OS credential integration (Windows Credential Manager, macOS Keychain) and verify secure access
2. Verify browser uses OS certificate store with proper validation
3. Test OS notification integration respects permission model
4. Verify file type association handlers are validated and sandboxed
5. Test protocol handler registration requires user confirmation
6. Verify OS-level print dialog prevents renderer access to print system
7. Test that OS share APIs require user gesture and confirmation
8. Verify browser respects OS security policies (AppLocker, Gatekeeper, SELinux)
9. Test that browser updates use OS-level signature verification
10. Verify browser profile directories use OS access controls
11. OS credential storage accessed securely (encrypted IPC)
12. OS certificate store used with proper validation
13. OS notifications require permission and are per-origin
14. File associations validated before handler invocation
15. Protocol handlers require user confirmation
16. Print system accessed via broker, not renderer
17. OS share APIs require user gesture
18. Browser respects OS security policies
19. Updates verified with OS-level signatures
20. Profile directories protected with OS ACLs

**Pass Criteria**: Secure credential access AND certificate store used AND handlers validated AND security policies respected

**Fail Criteria**: Insecure credential access OR certificate store bypassed OR handlers not validated OR policies ignored

**Evidence**: Credential access flow analysis, certificate store usage verification, file association tests, protocol handler registration flows, OS policy compliance tests, update signature verification, ACL analysis

**References**:

- Windows Credential Manager: https://docs.microsoft.com/en-us/windows/security/identity-protection/credential-guard/
- macOS Keychain: https://developer.apple.com/documentation/security/keychain_services
- Code Signing: https://developer.apple.com/documentation/xcode/notarizing_macos_software_before_distribution
- Windows AppLocker: https://docs.microsoft.com/en-us/windows/security/threat-protection/windows-defender-application-control/applocker/applocker-overview
- SELinux: https://www.redhat.com/en/topics/linux/what-is-selinux

## 6.8 Embedded Browser Security Assessments

This section covers assessment procedures for requirements EMB-REQ-1 through EMB-REQ-32, addressing the unique security challenges of embedded browsers (WebView components, browser engines integrated into native applications). These assessments focus on JavaScript bridge security, native API exposure control, content source trust management, and host application boundary protection.

### Assessment: EMB-REQ-1 (JavaScript bridge API allowlists)

**Reference**: EMB-REQ-1 - JavaScript bridges shall implement explicit allowlists of exposed native APIs with per-API access controls

**Given**: A conformant embedded browser with JavaScript bridge capability (EMB-1 or higher)

**Task**: JavaScript bridges expose native device APIs to web content, creating critical attack surfaces where unrestricted API exposure enables privilege escalation, data exfiltration, malware installation, and complete device compromise. Without explicit allowlists, malicious web content can invoke any native API through reflection or dynamic invocation. Explicit API allowlisting with per-API access controls, runtime immutability, reflection blocking, and comprehensive logging prevents bridge-based attacks while enabling controlled native functionality.

**Verification**:

1. Review the embedded browser's JavaScript bridge configuration and implementation code
2. Identify all native APIs exposed to web content through the JavaScript bridge
3. Verify that an explicit allowlist mechanism exists (configuration file, API declaration, or programmatic registration)
4. Attempt to call native APIs that are not in the allowlist from web content
5. Verify that per-API access controls exist (e.g., origin-based restrictions, permission requirements)
6. Test that the allowlist cannot be modified by web content at runtime
7. Attempt to use reflection or dynamic invocation to bypass the allowlist
8. Verify that the bridge logs all API access attempts including denied attempts
9. JavaScript bridge exposes only explicitly allowlisted native APIs
10. Configuration files or code clearly declare which APIs are accessible
11. Per-API access controls restrict which origins or contexts can call each API
12. Attempts to call non-allowlisted APIs result in errors or exceptions
13. Web content cannot modify the API allowlist at runtime
14. Reflection or dynamic method invocation does not bypass allowlist enforcement
15. All API access attempts are logged for security auditing

**Pass Criteria**: Only explicitly allowlisted APIs are callable from web content AND per-API access controls are enforced AND allowlist cannot be modified by web content

**Fail Criteria**: Any non-allowlisted API is callable OR access controls are bypassable OR web content can modify the allowlist

**Evidence**: JavaScript bridge configuration files, implementation code review, test results showing blocked API calls, security logs showing denied access attempts, penetration test reports

**References**:

- OWASP Mobile Top 10 - M1: Improper Platform Usage: https://owasp.org/www-project-mobile-top-10/
- Android WebView addJavascriptInterface Security: https://developer.android.com/reference/android/webkit/WebView#addJavascriptInterface(java.lang.Object,%20java.lang.String)
- iOS WKWebView Configuration: https://developer.apple.com/documentation/webkit/wkwebviewconfiguration
- Electron Context Bridge: https://www.electronjs.org/docs/latest/api/context-bridge
- CWE-749: Exposed Dangerous Method or Function: https://cwe.mitre.org/data/definitions/749.html

### Assessment: EMB-REQ-2 (JavaScript bridge input validation)

**Reference**: EMB-REQ-2 - All data crossing the JavaScript bridge shall be validated, sanitized, and type-checked on the native side

**Given**: A conformant embedded browser with JavaScript bridge capability (EMB-1 or higher)

**Task**: JavaScript bridge parameters originate from untrusted web content and can contain injection payloads, type confusion attacks, buffer overflows, path traversal sequences, or prototype pollution that exploit native code vulnerabilities. Without comprehensive validation, attackers can achieve SQL injection into native databases, command injection for arbitrary code execution, or path traversal to access sensitive files. Native-side validation with type checking, sanitization, range checking, and path canonicalization prevents injection attacks across the trust boundary.

**Verification**:

1. Identify all native APIs exposed via JavaScript bridge that accept parameters
2. For each API, review the native-side validation and sanitization logic
3. Create test cases with malicious inputs: SQL injection strings, path traversal sequences, command injection payloads, excessively long strings, null bytes, Unicode exploits
4. Invoke bridge APIs with malformed data: wrong types, missing parameters, extra parameters, null values, undefined values
5. Attempt to pass JavaScript objects with prototype pollution characteristics
6. Test that numeric parameters are range-checked and validated
7. Verify that file paths are canonicalized and validated before use
8. Confirm that validation failures trigger errors and logging rather than silent failures
9. All bridge API parameters undergo validation on the native side before processing
10. Type checking rejects parameters of incorrect types
11. String sanitization removes or escapes dangerous characters
12. Numeric parameters are range-checked
13. File paths are validated and canonicalized
14. Malicious inputs trigger validation errors without causing security issues
15. Validation failures are logged with sufficient detail for security monitoring
16. No SQL injection, command injection, or path traversal vulnerabilities exist

**Pass Criteria**: All bridge parameters are validated, sanitized, and type-checked AND malicious inputs are rejected safely AND validation failures are logged

**Fail Criteria**: Any injection vulnerability exists OR type checking is missing OR validation can be bypassed

**Evidence**: Code review showing validation logic, penetration test results, fuzzing test results, validation error logs, security assessment reports

**References**:

- OWASP Input Validation Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Input_Validation_Cheat_Sheet.html
- CWE-20: Improper Input Validation: https://cwe.mitre.org/data/definitions/20.html
- CWE-89: SQL Injection: https://cwe.mitre.org/data/definitions/89.html
- CWE-78: OS Command Injection: https://cwe.mitre.org/data/definitions/78.html
- Android WebView Security Best Practices: https://developer.android.com/develop/ui/views/layout/webapps/webview#security

### Assessment: EMB-REQ-3 (JavaScript bridge logging)

**Reference**: EMB-REQ-3 - JavaScript bridge communications shall be logged with sufficient detail for security auditing

**Given**: A conformant embedded browser with JavaScript bridge capability (EMB-1 or higher)

**Task**: JavaScript bridge logging is critical for detecting and investigating attacks where malicious web content attempts to exploit native APIs through the bridge. Without comprehensive audit logs, security teams cannot detect unauthorized API access, track attack patterns, or investigate security incidents. Proper logging of all bridge communications enables security monitoring systems to identify suspicious patterns such as repeated failed API calls, attempts to access restricted functionality, or unusual parameter values that may indicate injection attacks or reconnaissance activities.

**Verification**:

1. Configure the embedded browser to enable JavaScript bridge logging
2. Invoke various bridge APIs from web content
3. Review the generated logs and verify they contain: API name, timestamp, calling origin, parameters (with sensitive data redacted), return values, success/failure status
4. Attempt to call blocked or restricted APIs and verify denials are logged
5. Generate high-volume bridge traffic and verify logging continues without loss
6. Test that sensitive data (passwords, tokens) is redacted from logs
7. Verify logs are stored securely with appropriate access controls
8. Confirm log retention policies are documented and enforced
9. All JavaScript bridge API invocations are logged
10. Logs include sufficient context for security analysis (API, origin, timestamp)
11. Both successful and failed API calls are logged
12. Sensitive parameters are redacted or hashed in logs
13. Logs are tamper-resistant with integrity protection
14. Log retention policies balance security needs and privacy requirements
15. Logs are accessible to security monitoring systems

**Pass Criteria**: All bridge API calls are logged with sufficient detail AND sensitive data is redacted AND logs have integrity protection

**Fail Criteria**: API calls are not logged OR insufficient detail is recorded OR sensitive data appears in plaintext

**Evidence**: Log samples showing bridge API calls, log configuration files, security monitoring dashboards, log retention policy documentation

**References**:

- OWASP Logging Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Logging_Cheat_Sheet.html
- NIST SP 800-92: Guide to Computer Security Log Management: https://csrc.nist.gov/publications/detail/sp/800-92/final
- CWE-778: Insufficient Logging: https://cwe.mitre.org/data/definitions/778.html

### Assessment: EMB-REQ-4 (Context isolation)

**Reference**: EMB-REQ-4 - Embedded browsers shall implement context isolation to prevent web content from accessing host application objects

**Given**: A conformant embedded browser with context isolation capability (EMB-1 or higher)

**Task**: Context isolation is essential to prevent malicious web content from breaking out of its sandbox and directly accessing host application objects, which could lead to privilege escalation, data theft, or code execution in the host application context. Without proper isolation, attackers can enumerate the JavaScript global namespace to discover and exploit unintended host APIs, access sensitive application data structures, or manipulate host application behavior through prototype pollution. This boundary violation represents one of the most critical security threats in embedded browser architectures.

**Verification**:

1. Load web content in the embedded browser
2. From web content JavaScript, attempt to access global objects that might belong to the host: `window.hostApp`, `window.native`, `window.android`, `window.webkit`, etc.
3. Attempt to enumerate window properties to discover host-exposed objects
4. Test if web content can access Node.js globals (if applicable): `process`, `require`, `Buffer`, `global`
5. Verify that the JavaScript bridge API is the only official communication channel
6. Test that prototype pollution cannot affect host application objects
7. Confirm that context isolation is enforced even for trusted content origins
8. Verify that iframes inherit context isolation from the parent
9. Web content cannot access host application objects directly
10. Global namespace pollution from host application is prevented
11. Node.js globals (if applicable) are not accessible to web content
12. Only explicitly exposed JavaScript bridge APIs are accessible
13. Window property enumeration does not reveal internal objects
14. Prototype pollution attacks do not affect host application
15. Context isolation applies to all embedded content regardless of origin

**Pass Criteria**: Web content has no direct access to host objects AND only official bridge APIs are accessible

**Fail Criteria**: Any host application object is directly accessible from web content OR context isolation can be bypassed

**Evidence**: Penetration test results showing blocked access attempts, code review of context isolation implementation, test scripts attempting to access host objects, browser console showing security errors

**References**:

- Electron Context Isolation: https://www.electronjs.org/docs/latest/tutorial/context-isolation
- Chromium Isolated Worlds: https://chromium.googlesource.com/chromium/src/+/master/third_party/blink/renderer/bindings/core/v8/V8BindingDesign.md#Isolated-World
- iOS WKWebView JavaScript Isolation: https://developer.apple.com/documentation/webkit/wkwebview
- Android WebView Isolation: https://developer.android.com/reference/android/webkit/WebView

### Assessment: EMB-REQ-5 (User consent for sensitive APIs)

**Reference**: EMB-REQ-5 - Native APIs exposed via JavaScript bridges shall require explicit user consent for sensitive operations

**Given**: A conformant embedded browser exposing sensitive APIs via JavaScript bridge (EMB-2 or higher)

**Task**: User consent for sensitive APIs is critical to prevent malicious web content from silently accessing privacy-sensitive functionality like camera, microphone, location, files, or contacts without the user's knowledge. Without explicit consent requirements, attackers can exploit JavaScript bridge APIs to exfiltrate sensitive data, track user location, or access private information. Proper consent mechanisms protect users from invisible attacks where compromised or malicious web content attempts unauthorized access to device capabilities that could violate user privacy or security expectations.

**Verification**:

1. Identify all sensitive operations exposed via the JavaScript bridge (e.g., file access, location, camera, contacts, payments)
2. Attempt to invoke sensitive APIs from web content without prior user consent
3. Verify that a clear, non-dismissible consent dialog appears for each sensitive operation
4. Test that consent dialogs clearly identify the requesting origin and the specific permission being requested
5. Verify that consent can be granted permanently, temporarily (session-only), or denied
6. Test that denied permissions are enforced consistently
7. Verify that users can revoke previously granted permissions
8. Confirm that consent state persists across browser sessions according to user choice
9. Sensitive API calls trigger user consent prompts before execution
10. Consent dialogs clearly identify the origin and permission type
11. Users can grant, deny, or revoke permissions
12. Denied permissions prevent API execution
13. Consent state is properly persisted and enforced
14. No sensitive operations occur without explicit user consent
15. Consent UI cannot be spoofed or bypassed by web content

**Pass Criteria**: All sensitive API calls require explicit user consent AND consent UI is clear and non-spoofable AND permission state is properly enforced

**Fail Criteria**: Any sensitive operation occurs without user consent OR consent UI is bypassable OR permissions are not enforced

**Evidence**: Screenshots of consent dialogs, test results showing blocked operations without consent, user consent audit logs, permission state persistence verification

**References**:

- Android Runtime Permissions: https://developer.android.com/training/permissions/requesting
- iOS Permission Prompts: https://developer.apple.com/design/human-interface-guidelines/patterns/accessing-private-data
- W3C Permissions API: https://www.w3.org/TR/permissions/

### Assessment: EMB-REQ-6 (No system-level API exposure without controls)

**Reference**: EMB-REQ-6 - Host applications shall not expose system-level APIs (file system, process execution, native module loading) through JavaScript bridges without additional security controls

**Given**: A conformant embedded browser with JavaScript bridge capability (EMB-1 or higher)

**Task**: Exposing system-level APIs through JavaScript bridges without strict controls creates critical vulnerabilities that can lead to arbitrary code execution, data exfiltration, or complete system compromise. Malicious web content could exploit unrestricted file system access to read sensitive files, execute arbitrary commands to take control of the host system, or load native modules to escalate privileges. Path traversal attacks could bypass directory restrictions, and unbounded network socket access could enable attackers to pivot to internal systems, making proper security controls on system-level APIs absolutely essential for embedded browser security.

**Verification**:

1. Review all APIs exposed via the JavaScript bridge
2. Identify any system-level capabilities: file system access, process/command execution, native module loading, network socket access, registry access
3. For each system-level API, verify additional security controls exist: capability-based permissions, path allowlisting, command allowlisting, sandboxing, user consent
4. Attempt to use exposed file system APIs to access sensitive paths (/etc/passwd, C:\\Windows\\System32, application data directories)
5. Attempt to execute arbitrary commands or load arbitrary native modules
6. Test that path traversal sequences (../, ..\\) are blocked or neutralized
7. Verify that system-level operations are logged extensively
8. Confirm that least-privilege principles are enforced (minimal necessary access)
9. System-level APIs either not exposed or have strict security controls
10. File system access is restricted to specific allowlisted directories
11. Command execution is restricted to specific allowlisted commands or completely prohibited
12. Native module loading is restricted or prohibited
13. Path traversal attacks are prevented
14. System-level operations require elevated permissions or user consent
15. All system-level operations are logged with full details
16. Security controls cannot be bypassed

**Pass Criteria**: No unrestricted system-level APIs are exposed AND all system APIs have additional security controls AND controls are enforced effectively

**Fail Criteria**: Any system-level API is exposed without restrictions OR security controls can be bypassed OR arbitrary file/command access is possible

**Evidence**: API documentation, code review of exposed APIs, penetration test results, logs showing blocked system access attempts, security architecture documentation

**References**:

- CWE-78: OS Command Injection: https://cwe.mitre.org/data/definitions/78.html
- CWE-22: Path Traversal: https://cwe.mitre.org/data/definitions/22.html
- OWASP Command Injection: https://owasp.org/www-community/attacks/Command_Injection
- Electron Security Best Practices - Shell Execution: https://www.electronjs.org/docs/latest/tutorial/security#6-do-not-use-shellexecuteshellopen-or-related-methods-with-user-content
- Android File System Security: https://developer.android.com/training/data-storage

### Assessment: EMB-REQ-7 (Immutable bridge configuration)

**Reference**: EMB-REQ-7 - JavaScript bridge configurations shall be immutable after WebView initialization to prevent runtime tampering

**Given**: A conformant embedded browser with JavaScript bridge capability (EMB-1 or higher)

**Task**: Immutable bridge configuration prevents runtime tampering attacks where malicious code attempts to dynamically modify the JavaScript bridge to add new attack surfaces, remove security controls, or replace legitimate APIs with malicious implementations. If configuration can be changed after initialization, attackers could exploit race conditions, code injection vulnerabilities, or confused deputy scenarios to inject malicious APIs, escalate privileges, or disable security restrictions. Configuration immutability ensures that the security boundary established at initialization time cannot be undermined during runtime.

**Verification**:

1. Initialize the embedded browser with a specific JavaScript bridge configuration
2. After initialization, attempt to modify the bridge configuration from host application code
3. From web content, attempt to add new APIs to the bridge dynamically
4. Test if existing bridge APIs can be removed or replaced at runtime
5. Verify that configuration changes after initialization either fail or require browser restart
6. Test that web content cannot influence bridge configuration through any means
7. Review code to confirm configuration is set during initialization phase only
8. Verify that attempting to modify configuration triggers security logging
9. Bridge configuration is set during initialization and cannot be changed afterward
10. Host application cannot add or remove bridge APIs after initialization
11. Web content cannot influence bridge configuration
12. Attempts to modify configuration fail with appropriate errors
13. Configuration immutability is enforced at the code level
14. Any attempted configuration changes are logged as security events
15. Browser restart is required for configuration changes (if supported at all)

**Pass Criteria**: Bridge configuration is immutable after initialization AND modification attempts fail AND attempts are logged

**Fail Criteria**: Configuration can be modified after initialization OR web content can influence configuration

**Evidence**: Code review showing configuration immutability enforcement, test results showing failed modification attempts, security logs showing configuration change attempts, API documentation

**References**:

- Android WebView Configuration Best Practices: https://developer.android.com/reference/android/webkit/WebSettings
- iOS WKWebView Configuration Immutability: https://developer.apple.com/documentation/webkit/wkwebviewconfiguration
- Electron Security - Immutable Configuration: https://www.electronjs.org/docs/latest/tutorial/security
- CWE-732: Incorrect Permission Assignment: https://cwe.mitre.org/data/definitions/732.html

### Assessment: EMB-REQ-8 (Host credential protection)

**Reference**: EMB-REQ-8 - Embedded browsers shall prevent web content from accessing host application credentials, tokens, or cryptographic keys

**Given**: A conformant embedded browser with context isolation (EMB-1 or higher)

**Task**: Protecting host credentials from web content access is essential to prevent credential theft attacks where malicious web content attempts to steal authentication tokens, API keys, or cryptographic keys stored by the host application. If web content can access host credentials through JavaScript bridge APIs, shared storage, or side channels, attackers can impersonate the host application, access protected resources, or decrypt sensitive data. This credential isolation requirement prevents scenarios where a compromised web page loaded in the embedded browser could steal the host's authentication credentials and use them for unauthorized access.

**Verification**:

1. Store test credentials/tokens in the host application's secure storage (keychain, keystore, credential manager)
2. Load web content in the embedded browser
3. Attempt to access host credentials through various methods: JavaScript bridge APIs, localStorage inspection, cookie inspection, memory inspection
4. Verify that credentials stored by the host are isolated from web content storage
5. Test that shared storage mechanisms (if any) do not leak credentials
6. Attempt to extract credentials by triggering host application features that use them
7. Verify that authentication tokens are not exposed in error messages or logs accessible to web content
8. Test that cryptographic operations using host keys cannot be triggered arbitrarily by web content
9. Host application credentials are completely isolated from web content
10. No JavaScript bridge API exposes credentials directly or indirectly
11. Web content storage (localStorage, cookies, IndexedDB) is separate from host credential storage
12. Shared storage mechanisms do not leak credentials
13. Authentication tokens are not exposed in error messages or debug output
14. Host cryptographic keys cannot be accessed or used arbitrarily by web content
15. Credential isolation is maintained even for trusted origins

**Pass Criteria**: Web content has no access to host credentials AND credential storage is completely isolated AND cryptographic keys are protected

**Fail Criteria**: Any credential or token is accessible to web content OR cryptographic keys can be misused

**Evidence**: Penetration test results, code review of credential storage isolation, test attempts to access credentials, memory dumps showing isolation, security audit reports

**References**:

- Android Keystore System: https://developer.android.com/training/articles/keystore
- iOS Keychain Services: https://developer.apple.com/documentation/security/keychain_services
- CWE-522: Insufficiently Protected Credentials: https://cwe.mitre.org/data/definitions/522.html

### Assessment: EMB-REQ-9 (JavaScript bridge security review)

**Reference**: EMB-REQ-9 - All JavaScript bridge implementations shall be reviewed for injection vulnerabilities before production deployment

**Given**: A conformant embedded browser with JavaScript bridge capability (EMB-1 or higher)

**Task**: Security reviews for JavaScript bridge implementations are critical because bridges represent the most dangerous attack surface in embedded browsers, where improper input validation can lead to injection attacks, privilege escalation, or arbitrary code execution. Without formal security reviews, subtle vulnerabilities like SQL injection through bridge parameters, command injection in system-level APIs, or XSS through improperly sanitized return values can go undetected. Comprehensive security assessments by qualified professionals ensure that all bridge APIs are properly validated, sanitized, and protected against common attack vectors before they can be exploited in production.

**Verification**:

1. Obtain documentation of the security review process for JavaScript bridge implementations
2. Verify that a formal security code review was conducted before production deployment
3. Review security assessment reports for the JavaScript bridge implementation
4. Verify that common injection vulnerabilities were tested: SQL injection, command injection, path traversal, XSS, code injection
5. Confirm that automated security scanning tools were used (static analysis, dynamic analysis)
6. Verify that findings from security reviews were remediated before deployment
7. Confirm that security reviews are repeated after significant bridge changes
8. Verify that third-party security assessments were conducted (if applicable)
9. Documented security review process exists for JavaScript bridge code
10. Security code reviews were conducted by qualified security professionals
11. Common injection vulnerability types were specifically tested
12. Automated security scanning tools were applied
13. Security findings were tracked and remediated
14. Re-reviews occur after significant code changes
15. Security review reports are available for audit

**Pass Criteria**: Formal security review was conducted AND injection vulnerabilities were specifically tested AND findings were remediated

**Fail Criteria**: No security review was conducted OR injection vulnerabilities were not tested OR findings were not remediated

**Evidence**: Security review reports, code review checklists, penetration test reports, static analysis tool outputs, vulnerability remediation tracking records, security sign-off documentation

**References**:

- OWASP Code Review Guide: https://owasp.org/www-project-code-review-guide/
- CWE Top 25 Most Dangerous Software Weaknesses: https://cwe.mitre.org/top25/archive/2023/2023_top25_list.html
- NIST SP 800-53 - Security Assessment: https://csrc.nist.gov/publications/detail/sp/800-53/rev-5/final
- OWASP Mobile Application Security Verification Standard: https://github.com/OWASP/owasp-masvs

### Assessment: EMB-REQ-10 (Bridge API rate limiting)

**Reference**: EMB-REQ-10 - Host applications shall implement rate limiting on JavaScript bridge API calls to prevent abuse

**Given**: A conformant embedded browser with JavaScript bridge capability (EMB-2 or higher)

**Task**: Rate limiting on JavaScript bridge APIs prevents abuse scenarios where malicious web content floods the bridge with excessive API calls to perform denial-of-service attacks, exhaust system resources, or brute-force security controls. Without rate limits, attackers can rapidly probe for vulnerabilities, overwhelm logging systems to hide their tracks, or cause performance degradation that impacts legitimate users. Proper rate limiting also prevents reconnaissance attacks where malicious scripts systematically enumerate all available APIs or attempt to bypass security controls through repeated high-frequency attempts.

**Verification**:

1. Identify rate limits for each JavaScript bridge API (requests per second, burst limits)
2. Create test scripts that invoke bridge APIs at high frequency
3. Verify that rate limits are enforced: excessive calls are rejected or throttled
4. Test that rate limit violations trigger logging and security alerts
5. Verify that rate limits are per-origin (different origins have independent quotas)
6. Test that rate limits reset appropriately (per second, per minute, per session)
7. Attempt to bypass rate limits by using multiple execution contexts (iframes, workers)
8. Verify that legitimate use cases are not blocked by rate limits
9. Rate limits are defined and documented for all bridge APIs
10. Excessive API calls are rejected or throttled
11. Rate limit violations trigger security logging and alerts
12. Rate limits are enforced per-origin or per-context
13. Rate limits reset on appropriate time boundaries
14. Multiple contexts cannot bypass rate limits
15. Legitimate high-frequency use cases are accommodated
16. Rate limit parameters are configurable by host application

**Pass Criteria**: Rate limits are enforced on all bridge APIs AND violations are logged AND limits cannot be bypassed

**Fail Criteria**: No rate limiting exists OR rate limits are bypassable OR legitimate use is blocked

**Evidence**: Rate limit configuration documentation, test results showing throttling behavior, security logs showing rate limit violations, performance test results

**References**:

- OWASP API Security - Rate Limiting: https://owasp.org/API-Security/editions/2023/en/0xa4-unrestricted-resource-consumption/
- CWE-770: Allocation of Resources Without Limits: https://cwe.mitre.org/data/definitions/770.html
- NIST SP 800-95: Guide to Secure Web Services: https://csrc.nist.gov/publications/detail/sp/800-95/final
- Rate Limiting Best Practices: https://cloud.google.com/architecture/rate-limiting-strategies-techniques

### Assessment: EMB-REQ-11 (Granular capability-based permissions)

**Reference**: EMB-REQ-11 - JavaScript bridges shall support granular capability-based permissions rather than all-or-nothing access

**Given**: A conformant embedded browser with advanced bridge capabilities (EMB-2 or higher)

**Task**: Granular capability-based permissions prevent over-privileged access scenarios where granting access to one API inadvertently exposes all bridge functionality to potentially malicious web content. All-or-nothing permission models force developers to choose between denying all access or granting excessive privileges, creating security risks. Fine-grained permissions enable the principle of least privilege, allowing each origin to access only the specific APIs it needs while preventing lateral movement attacks where compromise of one feature leads to unauthorized access to unrelated sensitive functionality.

**Verification**: