CVE-2020-18771
📋 TL;DR
This vulnerability in Exiv2 image metadata library allows attackers to read beyond allocated memory boundaries when processing specially crafted Nikon image files. This can lead to information disclosure of sensitive data from application memory. Any system using Exiv2 0.27.99.0 to process untrusted image files is affected.
💻 Affected Systems
- Exiv2
📦 What is this software?
Exiv2 by Exiv2
⚠️ Risk & Real-World Impact
Worst Case
Complete memory disclosure leading to exposure of sensitive information like passwords, encryption keys, or other application data in memory, potentially enabling further attacks.
Likely Case
Partial memory leak exposing some application data, which could be used for information gathering or combined with other vulnerabilities.
If Mitigated
Limited impact with proper input validation and memory protections, potentially causing application crashes but no data exposure.
🎯 Exploit Status
Exploitation requires user to process a malicious Nikon image file. Public proof-of-concept exists in GitHub issue #756.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.27.2 and later
Vendor Advisory: https://github.com/Exiv2/exiv2/security/advisories/GHSA-5c2m-2c8c-8c8c
Restart Required: Yes
Instructions:
1. Update Exiv2 to version 0.27.2 or later. 2. For Linux distributions, use package manager: 'sudo apt update && sudo apt upgrade exiv2' (Debian/Ubuntu) or 'sudo yum update exiv2' (RHEL/CentOS). 3. Restart any services using Exiv2 library.
🔧 Temporary Workarounds
Disable Nikon MakerNote processing
allConfigure applications to skip processing of Nikon MakerNote metadata in image files
Application-specific configuration required
Input validation for image files
allImplement strict validation of image files before processing with Exiv2
Implement file type verification and size limits in application code
🧯 If You Can't Patch
- Isolate systems using Exiv2 and restrict processing of untrusted image files
- Implement network segmentation and monitor for suspicious image processing activity
🔍 How to Verify
Check if Vulnerable:
Check Exiv2 version: 'exiv2 --version' or 'dpkg -l | grep exiv2' on Debian systemsCheck Version:
exiv2 --versionVerify Fix Applied:
Confirm version is 0.27.2 or later: 'exiv2 --version | grep -q "0.27.[2-9]\|0.28" && echo "Patched"'📡 Detection & Monitoring
Log Indicators:
- Application crashes when processing image files
- Memory access violation errors in system logs
- Unusual image processing activity
Network Indicators:
- Unexpected image file uploads to web applications
- Large memory usage spikes during image processing
SIEM Query:
source="application.logs" AND ("segmentation fault" OR "buffer over-read" OR "exiv2 crash")🔗 References
- https://cwe.mitre.org/data/definitions/126.html
- https://github.com/Exiv2/exiv2/issues/756
- https://lists.debian.org/debian-lts-announce/2023/01/msg00004.html
- https://security.gentoo.org/glsa/202312-06
- https://cwe.mitre.org/data/definitions/126.html
- https://github.com/Exiv2/exiv2/issues/756
- https://lists.debian.org/debian-lts-announce/2023/01/msg00004.html
- https://security.gentoo.org/glsa/202312-06
