CVE-2021-47688
📋 TL;DR
This vulnerability allows local users to bypass WhiteBeam's allow-list functionality by truncating files before write verification occurs. It affects WhiteBeam servers where local users have access. The bypass could enable unauthorized file modifications.
💻 Affected Systems
- WhiteBeam
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Local privilege escalation or data corruption through unauthorized file writes to sensitive locations.
Likely Case
Local users bypassing security controls to modify files they shouldn't have access to.
If Mitigated
Minimal impact if proper access controls and monitoring are in place.
🎯 Exploit Status
Requires local access and understanding of the race condition between OpenFileDescriptor and VerifyCanWrite actions.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.2.2
Vendor Advisory: https://github.com/WhiteBeamSec/WhiteBeam/security/advisories/GHSA-3f8r-9483-pfxj
Restart Required: Yes
Instructions:
1. Update WhiteBeam to version 0.2.2 or later. 2. Restart the WhiteBeam service. 3. Verify the update was successful.
🔧 Temporary Workarounds
Restrict local access
linuxLimit local user access to WhiteBeam servers to trusted administrators only.
Monitor file operations
allImplement file integrity monitoring on critical files protected by WhiteBeam.
🧯 If You Can't Patch
- Implement strict access controls to limit which local users can access WhiteBeam servers.
- Deploy file integrity monitoring to detect unauthorized file modifications.
🔍 How to Verify
Check if Vulnerable:
Check WhiteBeam version: whitebeam --version. If version is 0.2.0 or 0.2.1, system is vulnerable.Check Version:
whitebeam --versionVerify Fix Applied:
Verify WhiteBeam version is 0.2.2 or later: whitebeam --version📡 Detection & Monitoring
Log Indicators:
- Unexpected file truncation operations
- Failed allow-list verification attempts
Network Indicators:
- None - local exploit only
SIEM Query:
Search for file truncation events on WhiteBeam protected files from non-admin users.