CVE-2021-34997
📋 TL;DR
This vulnerability allows authenticated remote attackers to bypass authentication mechanisms and upload arbitrary files to Commvault CommCell installations. Attackers can then execute arbitrary code with NETWORK SERVICE privileges. Affects Commvault CommCell version 11.22.22 installations.
💻 Affected Systems
- Commvault CommCell
📦 What is this software?
Commcell by Commvault
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to execute arbitrary code with NETWORK SERVICE privileges, potentially leading to lateral movement, data exfiltration, or ransomware deployment.
Likely Case
Unauthorized file upload leading to remote code execution, allowing attackers to gain persistent access, steal data, or deploy malware.
If Mitigated
Limited impact due to network segmentation, strict access controls, and monitoring preventing successful exploitation.
🎯 Exploit Status
Authentication bypass combined with file upload vulnerability makes exploitation straightforward for attackers with network access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Update to latest Commvault version (beyond 11.22.22)
Vendor Advisory: https://www.commvault.com/support/kb/security-updates
Restart Required: Yes
Instructions:
1. Backup current configuration. 2. Download latest Commvault update from official portal. 3. Apply update following vendor instructions. 4. Restart CommCell services. 5. Verify update successful.
🔧 Temporary Workarounds
Restrict Network Access
allLimit access to CommCell interface to trusted IP addresses only
Configure firewall rules to restrict access to CommCell ports (typically 8400-8600)
Disable Unnecessary Features
windowsDisable AppStudioUploadHandler if not required
Consult Commvault documentation for feature disable procedures
🧯 If You Can't Patch
- Implement strict network segmentation to isolate CommCell servers
- Deploy application control to prevent execution of unauthorized files
🔍 How to Verify
Check if Vulnerable:
Check CommCell version via CommCell Console > Help > About. If version is 11.22.22, system is vulnerable.Check Version:
In CommCell Console: Help > About displays version informationVerify Fix Applied:
Verify version is updated beyond 11.22.22 and test file upload functionality with malicious payloads.📡 Detection & Monitoring
Log Indicators:
- Unusual file uploads to AppStudioUploadHandler
- Authentication bypass attempts
- Unusual NETWORK SERVICE process execution
Network Indicators:
- Unexpected connections to CommCell ports from unauthorized sources
- Suspicious file upload patterns
SIEM Query:
source="commvault" AND (event="file_upload" OR event="auth_bypass")