CVE-2021-42129
📋 TL;DR
This command injection vulnerability in Ivanti Avalanche allows attackers with access to the Inforail Service to execute arbitrary commands on the system. Organizations running Ivanti Avalanche versions before 6.3.3 are affected, potentially leading to complete system compromise.
💻 Affected Systems
- Ivanti Avalanche
📦 What is this software?
Avalanche by Ivanti
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with administrative privileges, data exfiltration, ransomware deployment, and lateral movement across the network.
Likely Case
Unauthorized command execution leading to data theft, service disruption, and installation of backdoors or malware.
If Mitigated
Limited impact due to network segmentation, restricted service access, and proper authentication controls.
🎯 Exploit Status
Exploitation requires access to the Inforail Service but command injection vulnerabilities are typically straightforward to exploit once access is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.3.3 or later
Vendor Advisory: https://forums.ivanti.com/s/article/Security-Alert-CVE-s-Addressed-in-Avalanche-6-3-3
Restart Required: Yes
Instructions:
1. Download Ivanti Avalanche 6.3.3 or later from the Ivanti support portal. 2. Backup current configuration and data. 3. Run the installer and follow upgrade prompts. 4. Restart the Avalanche server and verify services are running.
🔧 Temporary Workarounds
Restrict Network Access to Inforail Service
windowsLimit network access to the Inforail Service port (typically 1777/TCP) to only trusted management systems using firewall rules.
Windows Firewall: New-NetFirewallRule -DisplayName "Block Inforail External" -Direction Inbound -Protocol TCP -LocalPort 1777 -Action Block -RemoteAddress Any
Implement Strong Authentication
allEnsure all access to Avalanche services requires strong authentication and consider implementing multi-factor authentication where possible.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Avalanche servers from critical systems
- Deploy application control solutions to prevent execution of unauthorized commands and binaries
🔍 How to Verify
Check if Vulnerable:
Check Avalanche version via the web interface (Admin > About) or by examining installed programs in Windows Control Panel.Check Version:
On Windows: wmic product where "name like 'Ivanti Avalanche%'" get versionVerify Fix Applied:
Verify version is 6.3.3 or higher and test that command injection attempts are properly sanitized or blocked.📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in Windows Event Logs (Event ID 4688)
- Suspicious process creation from Avalanche service account
- Failed authentication attempts to Inforail Service
Network Indicators:
- Unusual outbound connections from Avalanche server
- Traffic to command and control servers from Avalanche host
- Unexpected network scanning from Avalanche server
SIEM Query:
source="windows" EventCode=4688 AND (ProcessName="cmd.exe" OR ProcessName="powershell.exe") AND ParentProcessName contains "Avalanche"