CVE-2015-0675 in ASA
Summary
by MITRE
The failover ipsec implementation in Cisco Adaptive Security Appliance (ASA) Software 9.1 before 9.1(6), 9.2 before 9.2(3.3), and 9.3 before 9.3(3) does not properly validate failover communication messages, which allows remote attackers to reconfigure an ASA device, and consequently obtain administrative control, by sending crafted UDP packets over the local network to the failover interface, aka Bug ID CSCur21069.
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Analysis
by VulDB Data Team • 05/02/2022
The vulnerability described in CVE-2015-0675 represents a critical security flaw in Cisco Adaptive Security Appliance (ASA) software failover mechanisms that directly impacts the integrity and confidentiality of network security infrastructure. This issue affects specific versions of Cisco ASA software including 9.1 before 9.1(6), 9.2 before 9.2(3.3), and 9.3 before 9.3(3), where the failover IPsec implementation contains a significant validation weakness that can be exploited by remote attackers to gain complete administrative control over affected devices. The vulnerability specifically resides in the failover communication message validation process, which is a fundamental component of the ASA's high availability and redundancy features designed to ensure continuous network security operations.
The technical flaw manifests through improper validation of failover communication messages that are transmitted over the local network through the failover interface using UDP packets. This validation failure creates a pathway for malicious actors to craft and send specially designed UDP packets that can manipulate the failover process and ultimately reconfigure the ASA device. The vulnerability is particularly concerning because it allows remote attackers to execute arbitrary commands and gain administrative privileges without requiring authentication or physical access to the device. The attack vector specifically targets the local network interface used for failover communication, meaning that an attacker who can access the network segment where failover traffic occurs can exploit this vulnerability. This flaw directly maps to CWE-20, which describes improper input validation, and represents a classic example of how insufficient validation of communication protocols can lead to complete system compromise.
The operational impact of this vulnerability extends far beyond simple privilege escalation, as it fundamentally undermines the security posture of organizations relying on Cisco ASA failover configurations. When successfully exploited, the vulnerability allows attackers to gain administrative control over the ASA device, enabling them to modify firewall rules, access network traffic, disable security features, and potentially establish persistent backdoors within the network infrastructure. This compromise can result in complete network infiltration, data exfiltration, and disruption of critical security services that the ASA device provides. Organizations using failover configurations are particularly at risk since the vulnerability can be exploited even when the primary device appears to be functioning normally, as the failover interface remains accessible and vulnerable. The impact is further amplified by the fact that failover interfaces are often configured with minimal security restrictions, making them attractive targets for attackers seeking to compromise network security infrastructure.
The mitigation strategies for this vulnerability require immediate attention from network administrators and security teams responsible for Cisco ASA deployments. The primary and most effective solution involves applying the relevant Cisco security patches and updates that address the failover message validation flaw, specifically targeting the software versions mentioned in the vulnerability description. Organizations should also implement network segmentation and access controls to limit access to the failover interface, ensuring that only authorized management systems can communicate with the ASA failover interface. Network administrators should consider disabling failover functionality if it is not strictly required for their operational environment, as this eliminates the attack surface entirely. Additionally, implementing network monitoring and anomaly detection systems can help identify suspicious UDP traffic patterns that may indicate exploitation attempts. The vulnerability's classification under ATT&CK technique T1078.004 for valid accounts and T1566 for phishing highlights the need for comprehensive security monitoring that can detect both network-based and potentially credential-based exploitation attempts. Organizations should also conduct thorough security assessments of their failover configurations and ensure that failover interfaces are properly secured with appropriate access controls and network segmentation measures to prevent unauthorized access to critical network security infrastructure.