CVE-2021-42127
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on Ivanti Avalanche systems by sending maliciously crafted data to the Data Repository Service. It affects all Ivanti Avalanche versions before 6.3.3 that use the Inforail Service. Attackers can exploit this without authentication to gain full control of affected systems.
💻 Affected Systems
- Ivanti Avalanche
📦 What is this software?
Avalanche by Ivanti
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise leading to data theft, ransomware deployment, lateral movement across the network, and persistent backdoor installation.
Likely Case
Remote code execution allowing attackers to install malware, exfiltrate sensitive data, or disrupt enterprise mobility management operations.
If Mitigated
Limited impact if network segmentation prevents external access and strict access controls are in place, though internal threats remain.
🎯 Exploit Status
The vulnerability involves deserialization of untrusted data, which is a common attack vector with known exploitation patterns. While no public PoC is confirmed, the high CVSS score and remote unauthenticated nature make weaponization likely.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.3.3
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 from the Ivanti support portal. 2. Backup current configuration and data. 3. Run the installer to upgrade to version 6.3.3. 4. Restart the Avalanche server and verify the upgrade completed successfully.
🔧 Temporary Workarounds
Network Segmentation
allRestrict network access to the Avalanche server to only trusted management networks
Use firewall rules to block external access to Avalanche ports (typically 1777, 1778, 1779)
Service Disablement
windowsTemporarily disable the Data Repository Service if not required
sc stop "Avalanche Data Repository Service"
sc config "Avalanche Data Repository Service" start= disabled
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Avalanche servers from untrusted networks
- Deploy application control solutions to prevent execution of unauthorized binaries on Avalanche servers
🔍 How to Verify
Check if Vulnerable:
Check the Avalanche version in the web interface (Admin > About) or examine the installed program version in Windows Add/Remove ProgramsCheck Version:
Check the version displayed in the Avalanche web interface at Admin > AboutVerify Fix Applied:
Verify the version shows 6.3.3 or higher in the Avalanche web interface or Windows program list📡 Detection & Monitoring
Log Indicators:
- Unusual process creation from Avalanche services
- Failed deserialization attempts in application logs
- Unexpected network connections from Avalanche server
Network Indicators:
- Unusual traffic patterns to Avalanche Data Repository Service ports
- Malformed serialized data packets to port 1777-1779
SIEM Query:
source="avalanche" AND (event_type="deserialization_error" OR process_name="powershell.exe" OR process_name="cmd.exe")