CVE-2023-42101
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code by tricking users into opening malicious AR files in Ashlar-Vellum Cobalt. The flaw exists in AR file parsing where improper validation leads to out-of-bounds reads that can be leveraged for code execution. Users of Ashlar-Vellum Cobalt who open untrusted AR files are affected.
💻 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 in the context of the current user.
Likely Case
Remote code execution leading to data theft, malware installation, or lateral movement within the network.
If Mitigated
Limited impact with proper file validation and user awareness preventing malicious file execution.
🎯 Exploit Status
Exploitation requires crafting malicious AR files and social engineering to get users to open them. ZDI-CAN-20418 tracking suggests active research.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Ashlar-Vellum vendor advisory for specific patched versions
Vendor Advisory: Not provided in references - check Ashlar-Vellum website
Restart Required: Yes
Instructions:
1. Check Ashlar-Vellum website for security advisories
2. Download and install the latest patched version of Cobalt
3. Restart the application and any related services
🔧 Temporary Workarounds
Disable AR file processing
windowsPrevent Cobalt from processing AR files by removing file associations or using application controls
Windows: assoc .ar=
Windows: ftype ARFile=
User awareness training
allTrain users to avoid opening AR files from untrusted sources
🧯 If You Can't Patch
- Implement application whitelisting to prevent execution of unauthorized files
- Use email/web gateways to block AR file attachments from untrusted sources
🔍 How to Verify
Check if Vulnerable:
Check Cobalt version against vendor's patched version list. If using unpatched version and AR file processing is enabled, system is vulnerable.Check Version:
Launch Cobalt and check Help > About or version information in application interfaceVerify Fix Applied:
Verify installed version matches or exceeds vendor's patched version. Test with known safe AR files to ensure functionality.📡 Detection & Monitoring
Log Indicators:
- Unexpected crashes of Cobalt application
- AR file processing errors in application logs
- Unusual process creation from Cobalt executable
Network Indicators:
- Downloads of AR files from suspicious sources
- Outbound connections from Cobalt to unknown IPs
SIEM Query:
Process creation where parent_process contains 'cobalt' AND (process_name contains 'cmd' OR process_name contains 'powershell' OR process_name contains 'bash')