CVE-2024-20474 in Secure Client Software
Summary
by MITRE • 10/23/2024
A vulnerability in Internet Key Exchange version 2 (IKEv2) processing of Cisco Secure Client Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) of Cisco Secure Client.
This vulnerability is due to an integer underflow condition. An attacker could exploit this vulnerability by sending a crafted IKEv2 packet to an affected system. A successful exploit could allow the attacker to cause Cisco Secure Client Software to crash, resulting in a DoS condition on the client software.
Note: Cisco Secure Client Software releases 4.10 and earlier were known as Cisco AnyConnect Secure Mobility Client.
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Analysis
by VulDB Data Team • 10/23/2024
The vulnerability under discussion represents a critical denial of service weakness within Cisco Secure Client Software's implementation of Internet Key Exchange version 2 protocols. This issue stems from an integer underflow condition that occurs during the processing of IKEv2 packets, creating a scenario where maliciously crafted network traffic can trigger system instability. The vulnerability affects Cisco Secure Client Software versions 4.10 and earlier, which were previously known as Cisco AnyConnect Secure Mobility Client, indicating this flaw has persisted across multiple iterations of the security solution. The integer underflow condition manifests when the software fails to properly validate input parameters during IKEv2 packet processing, leading to unexpected behavior in memory management and control flow.
The exploitation mechanism for this vulnerability involves an unauthenticated remote attacker sending specifically crafted IKEv2 packets to a target system running the affected Cisco Secure Client Software. This attack vector operates entirely over the network without requiring any prior authentication credentials or privileged access, making it particularly dangerous as it can be executed from anywhere on the internet. The crafted packets are designed to trigger the integer underflow condition in the IKEv2 processing module, causing the software to enter an undefined state where normal operations cannot continue. When this occurs, the Cisco Secure Client Software experiences a complete crash, forcing users to manually restart the application and potentially disrupting their secure connectivity sessions.
The operational impact of this vulnerability extends beyond simple service disruption as it undermines the reliability and availability of critical network security infrastructure. Organizations relying on Cisco Secure Client for remote access and secure communications face potential business continuity issues when attackers successfully exploit this weakness, particularly in environments where continuous connectivity is essential for operations. The DoS condition affects only the client software itself rather than the underlying network infrastructure, but the implications are significant as it can render remote workers unable to establish or maintain secure connections to corporate networks. This vulnerability directly impacts the availability aspect of the CIA triad by compromising the ability of legitimate users to access secured resources through the affected client application.
Security practitioners should implement immediate mitigations including network segmentation to limit exposure, deployment of intrusion detection systems capable of identifying suspicious IKEv2 traffic patterns, and application whitelisting to prevent unauthorized execution of vulnerable software versions. Cisco has released patches addressing this integer underflow condition, and organizations should prioritize upgrading to the latest software releases that contain these fixes. The vulnerability aligns with CWE-191, which specifically addresses integer underflows in software implementations, and represents a classic example of how improper input validation can lead to system instability. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, covering network denial of service attacks, and demonstrates the importance of robust protocol implementation and input sanitization in security software development practices.