CVE-2021-21773
📋 TL;DR
This vulnerability allows an attacker to execute arbitrary code or cause a denial of service by exploiting an out-of-bounds write in Accusoft ImageGear's TIFF header processing. It affects systems running ImageGear 19.8 that process TIFF files from untrusted sources. The vulnerability can be triggered by a specially crafted malformed TIFF file.
💻 Affected Systems
- Accusoft ImageGear
📦 What is this software?
Imagegear by Accusoft
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with the privileges of the application processing the TIFF file, potentially leading to full system compromise.
Likely Case
Application crash (denial of service) or limited memory corruption leading to unstable behavior.
If Mitigated
No impact if the application is patched or doesn't process untrusted TIFF files.
🎯 Exploit Status
Exploitation requires the victim to process a malicious TIFF file. The vulnerability is well-documented with public proof-of-concept available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 19.9 or later
Vendor Advisory: https://www.accusoft.com/products/imagegear-collection/imagegear/
Restart Required: Yes
Instructions:
1. Contact Accusoft for updated ImageGear version 19.9 or later. 2. Replace the vulnerable ImageGear library with the patched version. 3. Recompile and redeploy any applications using ImageGear. 4. Restart affected services.
🔧 Temporary Workarounds
Block TIFF file processing
allConfigure applications to reject TIFF files or use alternative image processing libraries for TIFF files.
Input validation
allImplement strict file type validation and sanitization for uploaded TIFF files before processing with ImageGear.
🧯 If You Can't Patch
- Isolate systems using ImageGear from processing untrusted TIFF files
- Implement network segmentation and strict access controls for affected systems
🔍 How to Verify
Check if Vulnerable:
Check if ImageGear 19.8 is installed and used by applications. Review application dependencies and library versions.Check Version:
Check application documentation or contact vendor for version verification methods specific to your integration.Verify Fix Applied:
Verify ImageGear version is 19.9 or later. Test with known malicious TIFF samples to ensure proper handling.📡 Detection & Monitoring
Log Indicators:
- Application crashes when processing TIFF files
- Memory access violation errors in application logs
- Unexpected process termination
Network Indicators:
- Unusual outbound connections from applications processing TIFF files
- File uploads of TIFF files to vulnerable endpoints
SIEM Query:
source="application_logs" AND ("access violation" OR "segmentation fault" OR "memory corruption") AND "tiff"