CVE-2020-19131
📋 TL;DR
This vulnerability is a buffer overflow in LibTiff's tiffcrop utility that allows attackers to cause denial of service through the invertImage() function. It affects systems using vulnerable versions of LibTiff to process TIFF images. Attackers can exploit this by providing specially crafted TIFF files.
💻 Affected Systems
- LibTiff
- Applications using LibTiff library
- TIFF processing utilities
📦 What is this software?
Libtiff by Simplesystems
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise if combined with other vulnerabilities, though this specific CVE primarily enables denial of service.
Likely Case
Application crash and denial of service when processing malicious TIFF files, potentially disrupting image processing services.
If Mitigated
Limited impact with proper input validation and memory protections; denial of service may still occur but without escalation.
🎯 Exploit Status
Exploitation requires providing a malicious TIFF file to the vulnerable function. Public proof-of-concept exists in bug reports.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: LibTiff 4.1.0 and later
Vendor Advisory: http://bugzilla.maptools.org/show_bug.cgi?id=2831
Restart Required: Yes
Instructions:
1. Update LibTiff to version 4.1.0 or later. 2. Recompile applications using LibTiff. 3. Restart affected services. 4. For Linux distributions, use package manager: 'sudo apt update && sudo apt upgrade libtiff5' (Debian/Ubuntu) or 'sudo yum update libtiff' (RHEL/CentOS).
🔧 Temporary Workarounds
Disable tiffcrop utility
linuxRemove or restrict access to tiffcrop binary to prevent exploitation
sudo chmod 000 /usr/bin/tiffcrop
sudo mv /usr/bin/tiffcrop /usr/bin/tiffcrop.disabled
Input validation for TIFF files
allImplement strict validation of TIFF files before processing
🧯 If You Can't Patch
- Implement application-level input validation for TIFF files
- Use memory protection mechanisms like ASLR and DEP
🔍 How to Verify
Check if Vulnerable:
Check LibTiff version: 'tiffinfo -v' or 'dpkg -l | grep libtiff' or 'rpm -qa | grep libtiff'. Version 4.0.10 is vulnerable.Check Version:
tiffinfo -v 2>&1 | head -1Verify Fix Applied:
Confirm LibTiff version is 4.1.0 or later: 'tiffinfo -v' should show patched version.📡 Detection & Monitoring
Log Indicators:
- Application crashes with segmentation faults in tiffcrop
- Memory access violation errors
- Abnormal termination of TIFF processing services
Network Indicators:
- Unusual TIFF file uploads to image processing endpoints
- Large or malformed TIFF file transfers
SIEM Query:
process_name:tiffcrop AND (event_type:crash OR exit_code:139 OR exit_code:11)🔗 References
- http://blog.topsec.com.cn/%E5%A4%A9%E8%9E%8D%E4%BF%A1%E5%85%B3%E4%BA%8Elibtiff%E4%B8%ADinvertimage%E5%87%BD%E6%95%B0%E5%A0%86%E6%BA%A2%E5%87%BA%E6%BC%8F%E6%B4%9E%E7%9A%84%E5%88%86%E6%9E%90/
- http://bugzilla.maptools.org/show_bug.cgi?id=2831
- https://lists.debian.org/debian-lts-announce/2021/10/msg00004.html
- http://blog.topsec.com.cn/%E5%A4%A9%E8%9E%8D%E4%BF%A1%E5%85%B3%E4%BA%8Elibtiff%E4%B8%ADinvertimage%E5%87%BD%E6%95%B0%E5%A0%86%E6%BA%A2%E5%87%BA%E6%BC%8F%E6%B4%9E%E7%9A%84%E5%88%86%E6%9E%90/
- http://bugzilla.maptools.org/show_bug.cgi?id=2831
- https://lists.debian.org/debian-lts-announce/2021/10/msg00004.html
