CVE-2023-39340
📋 TL;DR
This vulnerability in Ivanti Connect Secure allows attackers to send specific requests that can cause a Denial of Service (DoS), potentially making the appliance unavailable. All versions below 22.6R2 are affected, impacting organizations using this VPN/remote access solution.
💻 Affected Systems
- Ivanti Connect Secure (formerly Pulse Connect Secure)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete service outage of the Connect Secure appliance, disrupting remote access for all users and potentially affecting business operations.
Likely Case
Intermittent service disruptions or performance degradation of the VPN/remote access service.
If Mitigated
Minimal impact with proper network segmentation and monitoring in place to detect and block attack attempts.
🎯 Exploit Status
The vulnerability requires sending specific requests but does not require authentication, making exploitation relatively straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 22.6R2 or later
Vendor Advisory: https://forums.ivanti.com/s/article/Security-fix-release-Ivanti-Connect-Secure-22-6R2-and-22-6R2-1?language=en_US
Restart Required: Yes
Instructions:
1. Download the 22.6R2 or later firmware from Ivanti support portal. 2. Backup current configuration. 3. Apply the firmware update through the admin interface. 4. Reboot the appliance as required.
🔧 Temporary Workarounds
Network Access Control
allRestrict access to Connect Secure appliances to trusted IP addresses only
Rate Limiting
allImplement rate limiting on network devices to limit DoS attack effectiveness
🧯 If You Can't Patch
- Implement strict network segmentation and firewall rules to limit access to Connect Secure appliances
- Deploy additional monitoring and alerting for unusual traffic patterns to the appliances
🔍 How to Verify
Check if Vulnerable:
Check the firmware version in the Connect Secure admin interface under System > Maintenance > VersionCheck Version:
Not applicable - version check is done through web admin interfaceVerify Fix Applied:
Verify the firmware version shows 22.6R2 or later after patching📡 Detection & Monitoring
Log Indicators:
- Unusual request patterns to the appliance
- Service restart or crash logs
- High resource utilization alerts
Network Indicators:
- Unusual traffic spikes to Connect Secure ports
- Repeated specific request patterns from single sources
SIEM Query:
source="ivanti_connect_secure" AND (event_type="service_restart" OR event_type="high_cpu" OR event_type="high_memory")