CVE-2018-0159 in IOS
Summary
by MITRE
A vulnerability in the implementation of Internet Key Exchange Version 1 (IKEv1) functionality in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to improper validation of specific IKEv1 packets. An attacker could exploit this vulnerability by sending crafted IKEv1 packets to an affected device during an IKE negotiation. A successful exploit could allow the attacker to cause an affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCuj73916.
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Analysis
by VulDB Data Team • 09/09/2024
The vulnerability described in CVE-2018-0159 represents a critical denial of service weakness within Cisco's Internet Key Exchange Version 1 implementation, specifically affecting IOS and IOS XE software platforms. This flaw resides in the IKEv1 protocol handling mechanism that governs secure key exchange for IPsec connections, making it particularly dangerous as it directly impacts the foundational security infrastructure of network devices. The vulnerability manifests when the affected Cisco devices fail to properly validate incoming IKEv1 packets during the negotiation phase, creating an exploitable condition that can be leveraged remotely without authentication requirements.
The technical exploitation of this vulnerability occurs through the careful crafting of malformed IKEv1 packets that trigger improper state handling within the Cisco IOS software stack. When an attacker sends specifically constructed packets to an affected device during IKE negotiation, the software's insufficient input validation causes a critical processing failure that ultimately results in a device reload or system crash. This improper validation aligns with common software security weaknesses categorized under CWE-248, which addresses "Uncaught Exception" conditions where programs fail to properly handle exceptional circumstances in their execution flow. The vulnerability demonstrates a classic example of how protocol implementation flaws can create denial of service conditions through malformed packet processing.
The operational impact of this vulnerability extends beyond simple service disruption as it affects the fundamental network security infrastructure that many organizations depend upon for secure communications. Network devices running vulnerable Cisco IOS software become susceptible to remote exploitation, potentially allowing attackers to repeatedly disrupt critical network services and communications channels. This vulnerability particularly affects enterprise networks that rely heavily on IPsec VPN connections for remote access and site-to-site connectivity, where a successful attack could result in significant business disruption and communication outages. The lack of authentication requirements for exploitation makes this vulnerability especially dangerous as it can be exploited by any remote attacker with network access to the affected device.
Organizations should implement immediate mitigations including applying the relevant Cisco security patches and updates that address the specific IKEv1 validation issues. Network segmentation strategies can help limit the attack surface by restricting access to vulnerable devices to only necessary administrative networks. Additionally, implementing monitoring solutions that can detect anomalous IKEv1 packet patterns may provide early warning of exploitation attempts. The vulnerability's classification under ATT&CK technique T1499.004 for network denial of service aligns with broader threat actor methodologies that target network infrastructure to create operational disruption. Organizations should also consider implementing access control lists to restrict IKEv1 traffic to trusted sources only, while maintaining comprehensive logging of IKE negotiation activities to detect potential exploitation attempts. The Cisco Bug ID CSCuj73916 specifically documents this vulnerability and provides detailed information about the affected software versions and recommended remediation steps.