CVE-2021-30475
📋 TL;DR
CVE-2021-30475 is a critical buffer overflow vulnerability in libaom's noise_model.c component that allows attackers to execute arbitrary code or cause denial of service. This affects any software using AOMedia's libaom library for AV1 video processing before March 24, 2021. Media processing applications, web browsers, and video players that use vulnerable libaom versions are at risk.
💻 Affected Systems
- libaom
- AOMedia AV1 codec library
- Applications using libaom (Chrome, Firefox, media players, video editors)
📦 What is this software?
Aomedia by Aomedia
Fedora by Fedoraproject
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with full system compromise, allowing attackers to install malware, steal data, or pivot to other systems.
Likely Case
Denial of service through application crashes or memory corruption leading to system instability.
If Mitigated
Limited impact through sandboxing or memory protection mechanisms, potentially causing only application crashes.
🎯 Exploit Status
Buffer overflow vulnerabilities in widely used media libraries are frequently weaponized. The fix commit shows clear memory corruption patterns that could be exploited.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: libaom from 2021-03-24 onward
Vendor Advisory: https://aomedia.googlesource.com/aom/+/12adc723acf02633595a4d8da8345742729f46c0
Restart Required: Yes
Instructions:
1. Update libaom to version from March 24, 2021 or later. 2. Update dependent applications (web browsers, media players). 3. Restart affected services and applications. 4. For Linux distributions, use package manager: 'sudo apt update && sudo apt upgrade libaom' (Debian/Ubuntu) or 'sudo yum update libaom' (RHEL/CentOS).
🔧 Temporary Workarounds
Disable AV1 video processing
allTemporarily disable AV1 codec support in applications to prevent exploitation
Application-specific configuration required
Memory protection controls
linuxEnable ASLR, DEP, and other memory protection mechanisms
echo 2 > /proc/sys/kernel/randomize_va_space
Check system hardening guides for platform-specific commands
🧯 If You Can't Patch
- Isolate systems using libaom from untrusted networks
- Implement strict input validation for media files and use sandboxing for media processing applications
🔍 How to Verify
Check if Vulnerable:
Check libaom version: 'aomdec --version' or check package version: 'dpkg -l | grep libaom' (Debian) or 'rpm -qa | grep libaom' (RHEL)Check Version:
aomdec --version 2>/dev/null | head -1 || dpkg -l libaom* 2>/dev/null || rpm -q libaom 2>/dev/nullVerify Fix Applied:
Verify libaom version is from March 24, 2021 or later: 'strings /usr/lib/libaom.so | grep -i "Mar 24 2021"' or check version >= 2.0.0📡 Detection & Monitoring
Log Indicators:
- Application crashes with segmentation faults in libaom
- Memory corruption errors in system logs
- Abnormal process termination of media applications
Network Indicators:
- Unusual AV1 media file transfers to vulnerable systems
- Exploit kit traffic patterns
SIEM Query:
process_name:"aom" AND (event_type:"crash" OR memory_violation:"true") OR file_type:"av1" AND suspicious_activity:"true"🔗 References
- https://aomedia.googlesource.com/aom/+/12adc723acf02633595a4d8da8345742729f46c0
- https://bugs.chromium.org/p/aomedia/issues/detail?id=2999
- https://lists.debian.org/debian-lts-announce/2023/09/msg00003.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZXCI33HXH6YSOGC2LPE2REQLMIDH6US4/
- https://security.gentoo.org/glsa/202401-32
- https://www.debian.org/security/2023/dsa-5490
- https://aomedia.googlesource.com/aom/+/12adc723acf02633595a4d8da8345742729f46c0
- https://bugs.chromium.org/p/aomedia/issues/detail?id=2999
- https://lists.debian.org/debian-lts-announce/2023/09/msg00003.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZXCI33HXH6YSOGC2LPE2REQLMIDH6US4/
- https://security.gentoo.org/glsa/202401-32
- https://www.debian.org/security/2023/dsa-5490
