CVE-2019-17539
📋 TL;DR
This vulnerability in FFmpeg before version 4.2 allows a NULL pointer dereference in the avcodec_open2 function, potentially leading to crashes, denial of service, or arbitrary code execution. It affects systems and applications that use vulnerable FFmpeg libraries for media processing. Users of FFmpeg-based software, such as media players, streaming services, or video editing tools, are at risk.
💻 Affected Systems
- FFmpeg
- Software using FFmpeg libraries (e.g., VLC, HandBrake, streaming servers)
📦 What is this software?
Ffmpeg by Ffmpeg
Ffmpeg by Ffmpeg
Ffmpeg by Ffmpeg
Ubuntu Linux by Canonical
Ubuntu Linux by Canonical
Ubuntu Linux by Canonical
⚠️ Risk & Real-World Impact
Worst Case
Exploitation could result in remote code execution, allowing an attacker to take full control of the affected system, potentially leading to data theft, system compromise, or further network propagation.
Likely Case
Most probable impact is denial of service, causing application crashes or instability when processing malicious media files, disrupting media services or user applications.
If Mitigated
With proper controls like input validation and sandboxing, the impact may be limited to localized crashes or reduced functionality, preventing broader system compromise.
🎯 Exploit Status
Exploitation involves crafting a malicious media file to trigger the NULL pointer dereference; public proof-of-concept details are available in the linked references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: FFmpeg 4.2 and later
Vendor Advisory: https://github.com/FFmpeg/FFmpeg/commit/8df6884832ec413cf032dfaa45c23b1c7876670c
Restart Required: Yes
Instructions:
1. Update FFmpeg to version 4.2 or later using your package manager (e.g., apt-get upgrade ffmpeg on Debian/Ubuntu). 2. Recompile any custom applications with the updated FFmpeg libraries. 3. Restart services or applications that use FFmpeg to apply the fix.
🔧 Temporary Workarounds
Disable vulnerable codec usage
allTemporarily disable or restrict the use of codecs that trigger the avcodec_open2 function in FFmpeg-based applications.
Configure application settings to avoid processing untrusted media files or use alternative libraries.
🧯 If You Can't Patch
- Implement strict input validation to reject or sanitize media files from untrusted sources.
- Isolate FFmpeg processes in sandboxed environments or containers to limit potential damage from exploitation.
🔍 How to Verify
Check if Vulnerable:
Run 'ffmpeg -version' and check if the version is below 4.2; also, inspect application dependencies for vulnerable FFmpeg libraries.Check Version:
ffmpeg -version | grep 'ffmpeg version'Verify Fix Applied:
After updating, run 'ffmpeg -version' to confirm version 4.2 or higher, and test with known malicious media files to ensure no crashes occur.📡 Detection & Monitoring
Log Indicators:
- Application crashes or segmentation faults in logs related to FFmpeg processes
- Error messages mentioning avcodec_open2 or NULL pointer dereference
Network Indicators:
- Unusual media file uploads or processing requests to FFmpeg-based services
- Increased error rates in media streaming or conversion endpoints
SIEM Query:
Example: search for 'ffmpeg' AND ('segmentation fault' OR 'NULL pointer') in application logs over the past 24 hours.🔗 References
- https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15733
- https://github.com/FFmpeg/FFmpeg/commit/8df6884832ec413cf032dfaa45c23b1c7876670c
- https://lists.debian.org/debian-lts-announce/2021/01/msg00026.html
- https://security.gentoo.org/glsa/202003-65
- https://usn.ubuntu.com/4431-1/
- https://www.debian.org/security/2020/dsa-4722
- https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15733
- https://github.com/FFmpeg/FFmpeg/commit/8df6884832ec413cf032dfaa45c23b1c7876670c
- https://lists.debian.org/debian-lts-announce/2021/01/msg00026.html
- https://security.gentoo.org/glsa/202003-65
- https://usn.ubuntu.com/4431-1/
- https://www.debian.org/security/2020/dsa-4722
