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threat-modeling.md

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Threat Model Analysis for google/exoplayer

Threat: Malicious Manifest Manipulation

  • Description: An attacker intercepts and modifies the media manifest (e.g., DASH MPD, HLS M3U8) delivered to the application. They could change URLs to point to malicious media segments, insert bogus initialization segments, alter DRM information to point to a compromised key server, or add excessive AdaptationSets/Representations to cause resource exhaustion. The attacker might use a Man-in-the-Middle (MITM) attack, DNS spoofing, or compromise the server hosting the manifest.
  • Impact: Denial of service (application crashes or becomes unresponsive), potential arbitrary code execution (if a vulnerability exists in ExoPlayer's parsing of the manipulated content or in a codec), redirection to malicious content, or failure to play DRM-protected content.
  • ExoPlayer Component Affected: ParsingLoadable, ManifestFetcher, DashManifestParser, HlsPlaylistParser, SsManifestParser, and potentially DRM-related components like DefaultDrmSessionManager if DRM information is manipulated.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Manifest Integrity Checks: Implement robust integrity checks. Use digital signatures (if supported) or cryptographic hashes (e.g., SHA-256) to verify the manifest. The application must verify this before passing the manifest to ExoPlayer.
    • Secure Manifest Delivery: Use HTTPS with strong TLS configurations and proper certificate validation.
    • Input Validation (Application Level): Implement sanity checks on values within the manifest.

Threat: Malicious Media Segment Injection

  • Description: An attacker intercepts and replaces legitimate media segments with crafted ones designed to exploit vulnerabilities in ExoPlayer's demuxers, decoders, or renderers. This could involve injecting malformed data into the bitstream to trigger buffer overflows, integer overflows, or other memory corruption issues. The attacker might use a MITM attack or compromise the CDN/server.
  • Impact: Denial of service (application crash), arbitrary code execution (potentially leading to device compromise), information disclosure.
  • ExoPlayer Component Affected: MediaCodecVideoRenderer, MediaCodecAudioRenderer, LibvpxVideoRenderer, FfmpegAudioRenderer, TextRenderer, and various Extractor implementations (e.g., Mp4Extractor, TsExtractor, MatroskaExtractor). The specific component depends on the media format.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Secure Segment Delivery: Use HTTPS with strong TLS configurations and certificate validation for all segment downloads.
    • Regular ExoPlayer Updates: Keep ExoPlayer updated to the latest version. Google frequently patches vulnerabilities in codecs and demuxers. This is crucial.
    • Fuzzing (Development Phase): ExoPlayer developers (and ideally, application developers) should use fuzzing.
    • Segment Integrity Check (If Possible): If possible, implement segment-level integrity checks.

Threat: DRM Circumvention (Client-Side)

  • Description: An attacker attempts to bypass the DRM system to extract decrypted content or obtain DRM keys. This could involve reverse-engineering the application, debugging ExoPlayer, exploiting vulnerabilities in the DRM client implementation, or attacking the secure storage of DRM keys.
  • Impact: Unauthorized access to and distribution of copyrighted content, financial losses.
  • ExoPlayer Component Affected: DefaultDrmSessionManager, FrameworkMediaDrm, and platform-specific DRM components (e.g., Widevine CDM on Android).
  • Risk Severity: High
  • Mitigation Strategies:
    • Use a Robust DRM System: Choose a well-established DRM system (Widevine, PlayReady, FairPlay).
    • Secure Key Storage: Utilize the platform's secure key storage mechanisms. Never store keys in easily accessible locations.
    • Obfuscation and Anti-Tampering: Employ code obfuscation and anti-tampering techniques. This is defense-in-depth.
    • Regular Security Audits: Conduct periodic security audits and penetration testing.

Threat: Vulnerabilities in ExoPlayer Dependencies

  • Description: ExoPlayer relies on underlying platform components and libraries (e.g., media codecs provided by the OS). Vulnerabilities in these dependencies could be exploited through ExoPlayer.
  • Impact: Varies, but could range from denial of service to arbitrary code execution.
  • ExoPlayer Component Affected: Indirectly affects all ExoPlayer components.
  • Risk Severity: High
  • Mitigation Strategies:
    • Dependency Management: Maintain a clear list of all dependencies.
    • Regular Updates: Keep all dependencies, including the OS and platform libraries, updated.
    • Vulnerability Scanning: Use software composition analysis (SCA) tools.