CVE-2015-4041
📋 TL;DR
This vulnerability in GNU Coreutils' sort utility allows attackers to trigger a heap-based buffer overflow via specially crafted long UTF-8 strings. The overflow can cause denial of service (application crash) or potentially allow arbitrary code execution. It affects 64-bit systems running vulnerable versions of GNU Coreutils.
💻 Affected Systems
- GNU Coreutils
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise if the sort utility is exposed to untrusted input.
Likely Case
Denial of service through application crashes when processing malicious UTF-8 strings.
If Mitigated
Limited impact if sort is not exposed to untrusted input or if input validation is implemented.
🎯 Exploit Status
Exploitation requires feeding malicious UTF-8 strings to the sort command. Public proof-of-concept exists in security advisories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 8.24 and later
Vendor Advisory: https://bugzilla.suse.com/show_bug.cgi?id=928749
Restart Required: No
Instructions:
1. Update GNU Coreutils to version 8.24 or later. 2. For Debian/Ubuntu: apt-get update && apt-get install coreutils. 3. For RHEL/CentOS: yum update coreutils. 4. For source compilation: Download latest from https://ftp.gnu.org/gnu/coreutils/ and compile.
🔧 Temporary Workarounds
Input validation wrapper
linuxCreate a wrapper script that validates input length before passing to sort
#!/bin/bash
MAX_LEN=1000
if [ ${#1} -gt $MAX_LEN ]; then
echo "Input too long"
exit 1
fi
sort "$@"
Use alternative sorting
allUse alternative sorting tools like Python sort or database sorting
python3 -c "import sys; print('\n'.join(sorted(sys.stdin.read().splitlines())))"
🧯 If You Can't Patch
- Restrict sort usage to trusted users only via sudoers or permissions
- Implement input validation for all scripts calling sort with external data
🔍 How to Verify
Check if Vulnerable:
Run: sort --version | grep 'sort (GNU coreutils)' && echo 'Check if version <= 8.23'Check Version:
sort --version | head -1Verify Fix Applied:
After update, run: sort --version | grep '8.2[4-9]\|9.' && echo 'Patched'📡 Detection & Monitoring
Log Indicators:
- Segmentation fault or crash logs from sort process
- Abnormal termination of sort commands
Network Indicators:
- Unusually long UTF-8 strings being passed to sort via network services
SIEM Query:
process.name:"sort" AND (event.outcome:"failure" OR event.action:"segmentation_fault")🔗 References
- http://openwall.com/lists/oss-security/2015/05/15/1
- https://bugzilla.suse.com/show_bug.cgi?id=928749
- https://github.com/pixelb/coreutils/commit/bea5e36cc876ed627bb5e0eca36fdfaa6465e940
- http://openwall.com/lists/oss-security/2015/05/15/1
- https://bugzilla.suse.com/show_bug.cgi?id=928749
- https://github.com/pixelb/coreutils/commit/bea5e36cc876ed627bb5e0eca36fdfaa6465e940
