CVE-2021-44335
📋 TL;DR
CVE-2021-44335 is a heap buffer overflow vulnerability in the ok-file-formats library's PNG processing function. Attackers can exploit this by providing specially crafted PNG files, potentially leading to arbitrary code execution or application crashes. Any software using the vulnerable ok-file-formats library is affected.
💻 Affected Systems
- ok-file-formats library
- Applications using ok-file-formats for PNG processing
📦 What is this software?
Ok File Formats by Ok File Formats Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with the privileges of the application processing the malicious PNG file, potentially leading to complete system compromise.
Likely Case
Application crash (denial of service) when processing malicious PNG files, with potential for information disclosure from heap memory.
If Mitigated
Application crash with limited impact if proper sandboxing and memory protections are enabled.
🎯 Exploit Status
Proof of concept demonstrates crash via heap buffer overflow. Full RCE exploitation would require bypassing modern memory protections.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in commit after 203defd (specific version not documented)
Vendor Advisory: https://github.com/brackeen/ok-file-formats/issues/17
Restart Required: Yes
Instructions:
1. Update ok-file-formats library to latest version. 2. Rebuild applications using the library. 3. Restart affected services.
🔧 Temporary Workarounds
Disable PNG processing
allDisable PNG file processing in applications using ok-file-formats if not required
Input validation
allImplement strict validation of PNG files before processing
🧯 If You Can't Patch
- Implement network segmentation to isolate systems using vulnerable library
- Deploy application allowlisting to prevent execution of unauthorized binaries
🔍 How to Verify
Check if Vulnerable:
Check if application uses ok-file-formats library and version. Test with proof-of-concept PNG file from GitHub issue.Check Version:
Check build configuration or dependency files for ok-file-formats version referenceVerify Fix Applied:
Verify library version is updated beyond vulnerable commit. Test with same proof-of-concept PNG file to confirm no crash.📡 Detection & Monitoring
Log Indicators:
- Application crashes when processing PNG files
- Memory access violation errors in application logs
Network Indicators:
- Unusual PNG file uploads to web applications
- PNG files with abnormal structure
SIEM Query:
source="application.log" AND ("segmentation fault" OR "heap overflow" OR "access violation") AND "png"