CVE-2023-0996
📋 TL;DR
This vulnerability allows attackers to exploit a buffer overflow in the strided image data parsing code of the emscripten wrapper for libheif by providing a crafted image file. This could lead to arbitrary code execution or denial of service. Systems using libheif with emscripten for HEIF image processing are affected.
💻 Affected Systems
- libheif with emscripten wrapper
📦 What is this software?
Libheif by Struktur
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment.
Likely Case
Denial of service through application crashes or memory corruption disrupting image processing services.
If Mitigated
Limited impact with proper memory protections (ASLR, DEP) and sandboxing, potentially causing only crashes.
🎯 Exploit Status
The vulnerability is in memory handling during image parsing, making exploitation straightforward with a malicious file.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version including PR #759 fix (check libheif repository for specific version)
Vendor Advisory: https://github.com/strukturag/libheif/pull/759
Restart Required: Yes
Instructions:
1. Update libheif to version including PR #759 fix. 2. Recompile any applications using libheif with emscripten. 3. Restart affected services.
🔧 Temporary Workarounds
Disable HEIF image processing
allTemporarily disable processing of HEIF/HEIC image formats in affected applications.
Configure application to reject HEIF/HEIC files or use alternative image formats.
Input validation and sanitization
allImplement strict validation of image files before processing, rejecting suspicious or malformed HEIF files.
Add file validation logic in application code to check image integrity before parsing.
🧯 If You Can't Patch
- Implement network segmentation to isolate systems processing HEIF images from critical infrastructure.
- Deploy web application firewalls (WAF) with rules to block malicious image uploads and monitor for exploitation attempts.
🔍 How to Verify
Check if Vulnerable:
Check if libheif is compiled with emscripten and if the version predates the fix in PR #759. Review application dependencies for vulnerable libheif versions.Check Version:
Check libheif version in build configuration or dependency files (e.g., package.json, CMakeLists.txt).Verify Fix Applied:
Verify libheif version includes the fix from PR #759. Test with known safe HEIF images to ensure proper parsing without crashes.📡 Detection & Monitoring
Log Indicators:
- Application crashes or segmentation faults during HEIF image processing
- Memory corruption warnings in system logs
Network Indicators:
- Unusual uploads of HEIF/HEIC files to web applications
- Traffic spikes to image processing endpoints
SIEM Query:
Search for events where application processes HEIF files followed by crash or error logs indicating memory issues.