CVE-2016-6461 in ASA
Summary
by MITRE
A vulnerability in the HTTP web-based management interface of the Cisco Adaptive Security Appliance (ASA) could allow an unauthenticated, remote attacker to inject arbitrary XML commands on the affected system. More Information: CSCva38556. Known Affected Releases: 9.1(6.10). Known Fixed Releases: 100.11(0.75) 100.15(0.137) 100.8(40.129) 96.2(0.95) 97.1(0.55) 97.1(12.7) 97.1(6.30).
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Analysis
by VulDB Data Team • 09/24/2024
The vulnerability identified as CVE-2016-6461 affects the Cisco Adaptive Security Appliance (ASA) family of network security devices, specifically targeting the HTTP web-based management interface. This critical flaw represents a classic example of XML External Entity (XXE) injection vulnerability that enables remote attackers to execute arbitrary commands on the affected system without requiring authentication. The vulnerability stems from insufficient input validation within the web management interface, allowing malicious XML data to be processed and interpreted by the underlying XML parser. Security researchers have classified this issue under CWE-611, which specifically addresses Improper Restriction of XML External Entity Reference, making it a direct descendant of well-known XML parsing vulnerabilities that have plagued enterprise systems for years. The attack vector is particularly dangerous because it operates entirely over the network without requiring any credentials, making it an attractive target for automated exploitation campaigns.
The technical implementation of this vulnerability occurs when the ASA device processes XML data through its web management interface, particularly during operations involving configuration management or status reporting. Attackers can craft specially formatted XML requests that contain malicious entity declarations, which when processed by the vulnerable XML parser, can lead to arbitrary code execution on the target system. This flaw enables attackers to perform a wide range of malicious activities including but not limited to command execution, data exfiltration, and system compromise. The vulnerability is particularly concerning because it affects the management plane of the security appliance itself, potentially allowing attackers to gain complete administrative control over the network security device. The attack can be executed through standard HTTP requests, making it easily exploitable by threat actors with basic network connectivity to the affected system. According to the ATT&CK framework, this vulnerability maps to T1059.007 for command and scripting interpreter and T1566.001 for spearphishing via social media, as attackers can leverage the compromised management interface to establish persistence and further network infiltration.
The operational impact of CVE-2016-6461 extends far beyond simple unauthorized access, as it fundamentally compromises the integrity and security posture of the entire network infrastructure. When an attacker successfully exploits this vulnerability, they gain the ability to execute arbitrary commands with the privileges of the web server process, potentially leading to complete system compromise and network-wide access. The affected Cisco ASA devices, which are deployed in critical network security roles, become potential entry points for attackers seeking to establish persistent access to corporate networks. This vulnerability particularly impacts organizations that rely heavily on ASA devices for perimeter security, as the compromised management interface can be used to bypass other security controls and escalate privileges. The vulnerability affects multiple versions of the ASA software, specifically the 9.1(6.10) release, and requires careful attention to ensure proper patching across all affected systems. Organizations should implement immediate mitigation strategies including network segmentation, firewall rule modifications, and monitoring for suspicious HTTP traffic patterns that may indicate exploitation attempts.
The remediation process for this vulnerability involves applying the vendor-supplied patches and updates that address the underlying XML parsing issue in the affected ASA software versions. Cisco has released multiple fixed releases including versions 100.11(0.75), 100.15(0.137), 100.8(40.129), 96.2(0.95), 97.1(0.55), 97.1(12.7), and 97.1(6.30), each containing the necessary code modifications to prevent the XML injection attack. Security administrators should conduct thorough testing of these patches in non-production environments before deployment to ensure compatibility with existing network configurations and avoid potential service disruptions. The mitigation strategy should also include implementing network-based controls such as firewall rules that restrict access to the web management interface from trusted networks only, and disabling the web interface entirely if it is not required for administrative purposes. Organizations should also consider implementing intrusion detection systems that can monitor for patterns consistent with XXE attack attempts, and establish comprehensive monitoring procedures to detect potential exploitation attempts. The vulnerability highlights the importance of regular security patch management and demonstrates how seemingly minor flaws in web application interfaces can have catastrophic consequences for network security infrastructure.