CVE-2020-18395
📋 TL;DR
CVE-2020-18395 is a NULL pointer dereference vulnerability in GNU Gama's ellipsoid.h component that allows attackers to cause denial of service through segmentation faults. The vulnerability affects Gama 2.04 users who process crafted input data. Attackers can crash the application by exploiting this flaw.
💻 Affected Systems
- GNU Gama
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete denial of service with application crashes, potentially disrupting geodetic survey operations and data processing workflows.
Likely Case
Application crashes when processing maliciously crafted input files, requiring manual restart and potentially causing data loss in active processing jobs.
If Mitigated
Limited impact with proper input validation and sandboxing; crashes would be contained to individual processes without affecting the entire system.
🎯 Exploit Status
Exploitation requires the ability to provide crafted input to the Gama application, which typically requires some level of access to the system or application.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 2.04 (check for specific patch releases)
Vendor Advisory: http://lists.gnu.org/archive/html/bug-gama/2019-04/msg00001.html
Restart Required: Yes
Instructions:
1. Check current Gama version. 2. Update to latest version from official GNU repositories. 3. Recompile if using source distribution. 4. Restart any Gama processes or services.
🔧 Temporary Workarounds
Input validation wrapper
linuxCreate a wrapper script that validates input files before passing them to Gama
#!/bin/bash
# Validate input file exists and has expected format
if [ -f "$1" ] && file "$1" | grep -q "text"; then
gama "$1"
else
echo "Invalid input file"
exit 1
fi
🧯 If You Can't Patch
- Restrict user access to Gama binary and input data directories
- Implement strict input validation and sanitization for all Gama input files
🔍 How to Verify
Check if Vulnerable:
Check Gama version: gama --version or check installed package versionCheck Version:
gama --version 2>&1 | head -1Verify Fix Applied:
Verify updated version is installed and test with known safe input files📡 Detection & Monitoring
Log Indicators:
- Segmentation fault errors in system logs
- Gama process crashes with SIGSEGV
- Core dumps in working directories
Network Indicators:
- N/A - primarily local file processing vulnerability
SIEM Query:
source="system_logs" AND ("segmentation fault" OR "SIGSEGV") AND process="gama"