CVE-2024-22053: Ivanti Connect Secure DOS Vulnerability

CVE-2024-22053 Overview

A heap overflow vulnerability exists in the IPSec component of Ivanti Connect Secure (versions 9.x and 22.x) and Ivanti Policy Secure. This vulnerability allows an unauthenticated malicious user to send specially crafted requests that can crash the service, resulting in a denial of service (DoS) condition. In certain conditions, the vulnerability may also allow an attacker to read contents from memory, potentially exposing sensitive information.

Critical Impact

Unauthenticated attackers can exploit this heap overflow to cause service disruption or potentially leak sensitive memory contents from Ivanti VPN gateway appliances.

Affected Products

• Ivanti Connect Secure versions 9.1 (R1 through R18)
• Ivanti Connect Secure versions 22.1 through 22.6
• Ivanti Policy Secure versions 9.0 and 9.1 (all releases)
• Ivanti Policy Secure versions 22.1 through 22.6

Discovery Timeline

• April 4, 2024 - CVE-2024-22053 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2024-22053

Vulnerability Analysis

This vulnerability is a heap-based buffer overflow (CWE-787) combined with improper check or handling of exceptional conditions (CWE-703) in the IPSec component of Ivanti's VPN gateway products. The flaw occurs when the IPSec service processes specially crafted network requests without properly validating input boundaries, allowing an attacker to write data beyond the allocated heap buffer.

The vulnerability is particularly concerning because it affects network perimeter devices that are directly exposed to the internet. Ivanti Connect Secure and Policy Secure are enterprise VPN solutions commonly deployed at network edges, making them attractive targets for attackers seeking initial access to corporate networks.

Root Cause

The root cause lies in insufficient bounds checking within the IPSec protocol handler. When processing incoming IPSec packets, the component fails to properly validate the size of certain data fields before copying them into heap-allocated memory buffers. This allows an attacker to overflow the buffer boundaries, potentially corrupting adjacent heap memory structures.

The secondary weakness (CWE-703) indicates that the component also lacks proper exception handling for malformed input, which contributes to both the crash behavior and the potential memory disclosure condition.

Attack Vector

The attack is conducted remotely over the network without requiring authentication. An attacker can craft malicious IPSec packets designed to trigger the heap overflow condition. The exploitation does not require user interaction, making it suitable for automated attacks.

The attack can result in two potential outcomes:

1. Denial of Service: By corrupting heap memory structures, the attacker can cause the IPSec service to crash, disrupting VPN connectivity for legitimate users.
2. Memory Disclosure: Under specific conditions, the overflow may allow reading of memory contents beyond the intended buffer, potentially exposing sensitive data such as session tokens, configuration data, or credentials stored in memory.

Detection Methods for CVE-2024-22053

Indicators of Compromise

• Unexpected crashes or restarts of the IPSec service on Ivanti Connect Secure or Policy Secure appliances
• Anomalous IPSec traffic patterns with malformed or unusually large packet payloads
• Memory access violations or segmentation faults in system logs related to the IPSec component
• Unusual spikes in failed VPN connection attempts followed by service unavailability

Detection Strategies

• Deploy network intrusion detection systems (IDS) with signatures for malformed IPSec packet detection
• Monitor Ivanti appliance logs for repeated service crashes or unexpected restarts of the IPSec daemon
• Implement network traffic analysis to identify anomalous IPSec packet sizes or malformed protocol structures
• Configure alerting for any memory corruption or heap overflow indicators in system diagnostics

Monitoring Recommendations

• Enable verbose logging on Ivanti Connect Secure and Policy Secure appliances to capture detailed IPSec processing events
• Establish baseline metrics for normal IPSec service behavior to detect anomalous patterns
• Monitor system resource utilization for unusual memory consumption patterns that may indicate exploitation attempts
• Implement continuous vulnerability scanning to identify unpatched Ivanti appliances in your environment

How to Mitigate CVE-2024-22053

Immediate Actions Required

• Apply the latest security patches from Ivanti immediately as referenced in the Ivanti Security Advisory
• Inventory all Ivanti Connect Secure and Policy Secure deployments to identify vulnerable versions
• Prioritize patching for internet-facing appliances that process IPSec traffic
• Review access logs for signs of exploitation attempts prior to patching

Patch Information

Ivanti has released security patches addressing this vulnerability. Organizations should consult the Ivanti Security Advisory for specific patch versions and upgrade instructions. The advisory covers multiple CVEs including CVE-2024-21894, CVE-2024-22052, CVE-2024-22053, and CVE-2024-22023, so applying the latest cumulative update will address all related vulnerabilities.

Workarounds

• Restrict IPSec traffic to trusted IP ranges using network firewall rules until patches can be applied
• Consider temporarily disabling IPSec functionality if not business-critical, relying on alternative VPN protocols
• Implement network segmentation to limit the exposure of Ivanti appliances to untrusted networks
• Deploy web application firewalls or network security appliances capable of deep packet inspection on IPSec traffic

# Example: Restrict IPSec access to trusted networks using iptables
# Apply on network firewall or security appliance protecting Ivanti devices
iptables -A INPUT -p udp --dport 500 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p udp --dport 500 -j DROP
iptables -A INPUT -p udp --dport 4500 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p udp --dport 4500 -j DROP