CVE-2021-42126
📋 TL;DR
This vulnerability allows an attacker with access to the Inforail Service in Ivanti Avalanche to escalate privileges, potentially gaining administrative control. It affects Ivanti Avalanche users running versions before 6.3.3. The attacker must already have some level of access to the system to exploit this flaw.
💻 Affected Systems
- Ivanti Avalanche
📦 What is this software?
Avalanche by Ivanti
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise where an attacker gains administrative privileges, potentially allowing them to deploy malware, exfiltrate sensitive data, or disrupt enterprise device management operations.
Likely Case
Privilege escalation leading to unauthorized access to sensitive configuration data, device management controls, or the ability to deploy malicious configurations to managed devices.
If Mitigated
Limited impact if proper network segmentation and access controls prevent unauthorized users from reaching the Inforail Service interface.
🎯 Exploit Status
Exploitation requires access to the Inforail Service interface, which typically requires some level of authentication. The vulnerability is in authorization controls, suggesting relatively straightforward exploitation once access is obtained.
🛠️ 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 Avalanche 6.3.3 from Ivanti support portal. 2. Backup current configuration and database. 3. Run the installer to upgrade to version 6.3.3. 4. Restart the Avalanche server and verify the upgrade completed successfully.
🔧 Temporary Workarounds
Restrict Inforail Service Access
allLimit network access to the Inforail Service port (typically 1777) to only authorized administrative systems using firewall rules.
Implement Network Segmentation
allPlace the Avalanche server in a restricted network segment with limited access to only necessary management systems.
🧯 If You Can't Patch
- Implement strict access controls to limit who can connect to the Inforail Service interface
- Monitor for unusual privilege escalation attempts and review access logs regularly
🔍 How to Verify
Check if Vulnerable:
Check the Avalanche version in the web interface under Help > About, or check the installed version in Windows Programs and Features. If version is below 6.3.3, the system is vulnerable.Check Version:
In Avalanche web interface: Navigate to Help > About to view version informationVerify Fix Applied:
After upgrading, verify the version shows 6.3.3 or higher in the Avalanche web interface under Help > About.📡 Detection & Monitoring
Log Indicators:
- Unusual privilege escalation attempts in Avalanche logs
- Multiple failed authorization attempts followed by successful administrative actions
- User accounts performing actions beyond their normal privilege level
Network Indicators:
- Unusual connections to Inforail Service port (typically 1777) from non-administrative systems
- Traffic patterns suggesting privilege escalation attempts
SIEM Query:
source="avalanche" AND (event_type="authorization_failure" OR event_type="privilege_escalation")