CVE-2024-21894
📋 TL;DR
A heap overflow vulnerability in the IPSec component of Ivanti Connect Secure and Policy Secure gateways allows unauthenticated attackers to send specially crafted requests to crash the service, causing denial of service. In certain conditions, this may lead to remote code execution. Affects Ivanti Connect Secure 9.x and 22.x, and Ivanti Policy Secure gateways.
💻 Affected Systems
- Ivanti Connect Secure
- Ivanti Policy Secure
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with SYSTEM/root privileges leading to complete system compromise, data exfiltration, and persistent backdoor installation.
Likely Case
Service crash causing denial of service, disrupting VPN and secure access services for all users.
If Mitigated
Limited to denial of service if exploit fails to achieve code execution, but service disruption still impacts business operations.
🎯 Exploit Status
CVSS 9.8 indicates trivial exploitation with high impact. Multiple related CVEs suggest active targeting.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Ivanti security advisory for specific patched versions
Restart Required: Yes
Instructions:
1. Review Ivanti security advisory. 2. Download appropriate patch for your version. 3. Apply patch via Ivanti management interface. 4. Restart affected services or appliance.
🔧 Temporary Workarounds
Disable IPSec if not required
allTemporarily disable IPSec functionality if not essential for operations
Via Ivanti management interface: Configuration > VPN > IPSec > Disable
Network segmentation and access control
allRestrict network access to IPSec services to trusted sources only
firewall rules to limit UDP 500, 4500 and ESP protocol to required sources
🧯 If You Can't Patch
- Isolate affected systems from internet and restrict internal access
- Implement intrusion detection/prevention systems to monitor for exploit attempts
🔍 How to Verify
Check if Vulnerable:
Check Ivanti appliance version via web interface: System > Maintenance > Version InformationCheck Version:
Via SSH: show version full (if CLI access available)Verify Fix Applied:
Verify version matches patched release from Ivanti advisory and test IPSec connectivity📡 Detection & Monitoring
Log Indicators:
- IPSec service crashes
- Unusual IPSec connection attempts
- Memory allocation errors in system logs
Network Indicators:
- Malformed IPSec packets
- Spike in IPSec connection attempts from single sources
- UDP 500/4500 traffic patterns
SIEM Query:
source="ivanti*" AND ("IPSec" OR "VPN") AND ("crash" OR "overflow" OR "memory")🔗 References
- https://forums.ivanti.com/s/article/SA-CVE-2024-21894-Heap-Overflow-CVE-2024-22052-Null-Pointer-Dereference-CVE-2024-22053-Heap-Overflow-and-CVE-2024-22023-XML-entity-expansion-or-XXE-for-Ivanti-Connect-Secure-and-Ivanti-Policy-Secure-Gateways?language=en_US
- https://forums.ivanti.com/s/article/SA-CVE-2024-21894-Heap-Overflow-CVE-2024-22052-Null-Pointer-Dereference-CVE-2024-22053-Heap-Overflow-and-CVE-2024-22023-XML-entity-expansion-or-XXE-for-Ivanti-Connect-Secure-and-Ivanti-Policy-Secure-Gateways?language=en_US
