CVE-2016-6432 in ASA
Summary
by MITRE
A vulnerability in the Identity Firewall feature of Cisco ASA Software before 9.6(2.1) could allow an unauthenticated, remote attacker to cause a reload of the affected system or to remotely execute code. The vulnerability is due to a buffer overflow in the affected code area. An attacker could exploit this vulnerability by sending a crafted NetBIOS packet in response to a NetBIOS probe sent by the ASA software. An exploit could allow the attacker to execute arbitrary code and obtain full control of the system or cause a reload of the affected system. Note: Only traffic directed to the affected system can be used to exploit this vulnerability. This vulnerability affects systems configured in routed and transparent firewall mode and in single or multiple context mode. This vulnerability can be triggered by IPv4 traffic.
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Analysis
by VulDB Data Team • 09/24/2024
The vulnerability identified as CVE-2016-6432 represents a critical buffer overflow flaw within Cisco Adaptive Security Appliance (ASA) software affecting versions prior to 9.6(2.1). This weakness resides in the Identity Firewall feature and demonstrates a fundamental design flaw that allows remote attackers to execute arbitrary code or force system reloads without authentication. The vulnerability operates through a specific attack vector involving crafted NetBIOS packets that exploit a memory corruption issue in the processing of NetBIOS probes. The buffer overflow occurs when the ASA software receives maliciously constructed NetBIOS responses, leading to unpredictable system behavior and potential complete system compromise.
The technical exploitation of this vulnerability requires the attacker to send specially crafted NetBIOS packets in response to probes initiated by the ASA software itself. This attack mechanism aligns with common buffer overflow exploitation techniques where insufficient input validation leads to memory corruption. The flaw affects systems operating in various configurations including routed and transparent firewall modes, as well as single and multiple context deployments. This broad impact scope indicates that the vulnerability is not limited to specific deployment scenarios but rather represents a fundamental weakness in the software's packet processing logic. The vulnerability specifically targets IPv4 traffic, making it particularly concerning for environments where legacy protocols remain in use.
The operational impact of this vulnerability extends beyond simple denial of service to encompass complete system compromise and potential lateral movement within network infrastructure. When successfully exploited, the vulnerability allows attackers to gain full control over the affected ASA appliance, potentially enabling them to modify firewall rules, redirect traffic, or establish persistent access points within the network. The ability to cause system reloads represents both a denial of service vector and a potential stepping stone for more sophisticated attacks, as system restarts may provide opportunities for privilege escalation or exploitation of additional vulnerabilities. This vulnerability particularly threatens network security posture as ASA appliances typically serve as critical security gateways in enterprise environments.
Organizations affected by CVE-2016-6432 should prioritize immediate remediation through official Cisco software updates and patches. The vulnerability's classification as a remote code execution flaw places it within the high-risk category of cybersecurity threats, warranting urgent attention from security teams. Network segmentation and access controls should be implemented to limit the potential attack surface, while monitoring systems should be configured to detect anomalous NetBIOS traffic patterns. The vulnerability's characteristics align with ATT&CK technique T1059.007 for command and scripting interpreter and T1499.004 for network disruption, highlighting the multi-faceted nature of potential exploitation. Security professionals should also consider implementing network-based intrusion detection systems to identify and block malicious NetBIOS traffic patterns. The CWE (Common Weakness Enumeration) classification for this vulnerability would fall under CWE-121, heap-based buffer overflow, given the nature of the memory corruption. Organizations should also conduct thorough vulnerability assessments to identify any other potentially affected systems and ensure proper network monitoring is in place to detect exploitation attempts.