CVE-2025-2020
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code by tricking users into opening malicious VC6 files in Ashlar-Vellum Cobalt software. The flaw exists in file parsing where improper validation leads to buffer overflow. Users of affected Cobalt installations are at risk.
💻 Affected Systems
- Ashlar-Vellum Cobalt
📦 What is this software?
Cobalt by Ashlar
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the affected system, potentially leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Local privilege escalation leading to data exfiltration, installation of persistent malware, or system disruption.
If Mitigated
Limited impact with proper application sandboxing and user privilege restrictions, potentially resulting only in application crash.
🎯 Exploit Status
Exploitation requires user interaction (opening malicious file) and knowledge of buffer overflow techniques. The vulnerability is documented by ZDI but no public exploit code is available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Ashlar-Vellum security advisory for specific patched version
Vendor Advisory: https://www.ashlar.com/security-advisories
Restart Required: No
Instructions:
1. Check current Cobalt version. 2. Visit Ashlar-Vellum support portal. 3. Download and apply the latest security update. 4. Verify installation completes successfully.
🔧 Temporary Workarounds
Block VC6 file extensions
allPrevent processing of VC6 files at the system or network level
Windows: Use Group Policy to block .vc6 file execution
macOS: Use mdfind to identify and quarantine VC6 files
Application sandboxing
allRun Cobalt in restricted environment to limit potential damage
Windows: Use AppLocker to restrict Cobalt permissions
macOS: Use sandbox-exec to run Cobalt in sandbox
🧯 If You Can't Patch
- Disable automatic opening of VC6 files and train users to avoid untrusted VC6 files
- Implement application whitelisting to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check Cobalt version against vendor's security advisory. If using unpatched version, system is vulnerable.Check Version:
Cobalt: Help → About Cobalt (GUI) or check application properties in systemVerify Fix Applied:
Verify Cobalt version matches or exceeds patched version specified in vendor advisory. Test with known safe VC6 files.📡 Detection & Monitoring
Log Indicators:
- Application crashes with memory access violations
- Unexpected child processes spawned from Cobalt
- Unusual file access patterns from Cobalt process
Network Indicators:
- Outbound connections from Cobalt to unknown IPs
- DNS requests for suspicious domains following VC6 file processing
SIEM Query:
Process creation where parent_process contains 'cobalt' AND (process_name contains 'cmd' OR process_name contains 'powershell' OR process_name contains 'bash')