CVE-2017-6610 in ASA
Summary
by MITRE
A vulnerability in the Internet Key Exchange Version 1 (IKEv1) XAUTH code of Cisco ASA Software could allow an authenticated, remote attacker to cause a reload of an affected system. The vulnerability is due to insufficient validation of the IKEv1 XAUTH parameters passed during an IKEv1 negotiation. An attacker could exploit this vulnerability by sending crafted parameters. Note: Only traffic directed to the affected system can be used to exploit this vulnerability. This vulnerability only affects systems configured in routed firewall mode and in single or multiple context mode. This vulnerability can be triggered by IPv4 or IPv6 traffic. A valid IKEv1 Phase 1 needs to be established to exploit this vulnerability, which means that an attacker would need to have knowledge of a pre-shared key or have a valid certificate for phase 1 authentication. This vulnerability affects Cisco ASA Software running on the following products: Cisco ASA 1000V Cloud Firewall, Cisco ASA 5500 Series Adaptive Security Appliances, Cisco ASA 5500-X Series Next-Generation Firewalls, Cisco ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers, Cisco Adaptive Security Virtual Appliance (ASAv), Cisco ASA for Firepower 9300 Series, Cisco ISA 3000 Industrial Security Appliance. Fixed versions: 9.1(7.7) 9.2(4.11) 9.4(4) 9.5(3) 9.6(1.5). Cisco Bug IDs: CSCuz11685.
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Analysis
by VulDB Data Team • 08/25/2024
The vulnerability described in CVE-2017-6610 represents a critical weakness in the Internet Key Exchange Version 1 implementation within Cisco Adaptive Security Appliances. This flaw specifically targets the XAUTH (Extended Authentication) component of the IKEv1 protocol, which serves as a crucial authentication mechanism for establishing secure communication channels between network devices. The vulnerability stems from inadequate parameter validation during the IKEv1 negotiation process, creating a potential attack vector that could be exploited by authenticated remote adversaries. The security implications are significant because IKEv1 serves as the foundation for establishing secure VPN connections and IPsec tunnels, making this weakness particularly dangerous in network security contexts. The vulnerability demonstrates a classic example of insufficient input validation, which aligns with CWE-20, a well-documented weakness in software design that leads to various security issues including denial of service and potential system compromise.
The operational impact of this vulnerability extends beyond simple service disruption, as it enables a remote attacker to force a complete system reload of affected Cisco ASA devices. This type of denial of service attack can have cascading effects on network security infrastructure, potentially disrupting critical communications and leaving networks vulnerable to other attacks during the recovery period. The exploit requires specific conditions to be met, including the establishment of a valid IKEv1 Phase 1 negotiation, which means attackers must possess either a pre-shared key or valid certificate for authentication purposes. This requirement provides some protection against casual exploitation but does not eliminate the threat entirely, as attackers who have gained access to legitimate credentials or have discovered weak authentication mechanisms could leverage this vulnerability. The attack vector is particularly concerning because it operates at the network protocol level, where the attacker can manipulate parameters during the authentication phase to trigger the system's reload mechanism.
Systems affected by this vulnerability are limited to specific Cisco ASA product lines configured in routed firewall mode or single/multiple context mode, which includes a substantial portion of enterprise security infrastructure. The vulnerability's impact is not limited to IPv4 traffic but also extends to IPv6 communications, making it relevant across modern network environments that utilize both protocol versions. This dual protocol support increases the attack surface and makes the vulnerability more pervasive across different network deployments. The affected products include Cisco ASA 1000V Cloud Firewall, various ASA 5500 Series appliances, ASA 5500-X Next-Generation Firewalls, and several other security modules across different Cisco platforms. The attack requires only traffic directed toward the vulnerable system, meaning that the exploit can be executed from external networks without requiring complex network positioning or insider access. This characteristic makes the vulnerability particularly dangerous in environments where external network traffic is not fully controlled or filtered, as it could be exploited by adversaries without requiring physical access to the network infrastructure.
Cisco has addressed this vulnerability through multiple software releases, with fixed versions including 9.1(7.7), 9.2(4.11), 9.4(4), 9.5(3), and 9.6(1.5). The remediation process requires administrators to upgrade their Cisco ASA software to one of these patched versions, which includes the necessary code modifications to properly validate IKEv1 XAUTH parameters. This fix represents a direct response to the input validation weakness and incorporates additional checks to prevent malformed parameters from triggering system reloads. Organizations should implement a comprehensive patch management strategy to address this vulnerability, considering the critical nature of the affected security appliances and their role in network protection. The vulnerability's presence in multiple product lines and software versions underscores the importance of thorough inventory management and coordinated patching efforts across all affected systems. From an operational security perspective, this vulnerability aligns with ATT&CK technique T1499.004, which involves network disruption through denial of service attacks, demonstrating how protocol-level weaknesses can be exploited to compromise system availability and network security posture.
The technical implementation of this vulnerability demonstrates the critical importance of proper input validation in security-critical code sections. The insufficient validation of IKEv1 XAUTH parameters represents a design flaw that could potentially be exploited to cause more severe consequences than simple service disruption. Network administrators should implement additional monitoring and logging capabilities to detect potential exploitation attempts, as the system reload behavior may be observable through security information and event management systems. The vulnerability's classification as a remote authenticated attack means that organizations must maintain strong credential management practices and implement proper access controls to prevent unauthorized exploitation. This case highlights the ongoing need for security audits of core protocol implementations and the importance of maintaining up-to-date security patches across all network infrastructure components. The remediation process should include thorough testing of patched software in controlled environments before deployment to production systems to ensure that the fix does not introduce compatibility issues or unintended side effects in existing network configurations.