CVE-2016-6366 in ASA
Summary
by MITRE
Buffer overflow in Cisco Adaptive Security Appliance (ASA) Software through 9.4.2.3 on ASA 5500, ASA 5500-X, ASA Services Module, ASA 1000V, ASAv, Firepower 9300 ASA Security Module, PIX, and FWSM devices allows remote authenticated users to execute arbitrary code via crafted IPv4 SNMP packets, aka Bug ID CSCva92151 or EXTRABACON.
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Analysis
by VulDB Data Team • 09/25/2024
The vulnerability described in CVE-2016-6366 represents a critical buffer overflow flaw within Cisco Adaptive Security Appliance (ASA) software versions up to 9.4.2.3. This security weakness affects multiple Cisco security appliances including the ASA 5500 series, ASA 5500-X platforms, ASA Services Module, ASA 1000V virtual appliances, ASAv, Firepower 9300 ASA Security Module, PIX devices, and FWSM systems. The flaw specifically manifests when the affected devices process crafted IPv4 SNMP packets, creating a remote code execution vector that could be exploited by authenticated attackers. This vulnerability is particularly concerning given the widespread deployment of Cisco ASA appliances in enterprise network security infrastructures, making it a prime target for malicious actors seeking to compromise network perimeters.
The technical implementation of this buffer overflow occurs within the SNMP packet processing functionality of the Cisco ASA software stack. When an authenticated user sends specially crafted IPv4 SNMP packets to the vulnerable device, the system fails to properly validate the packet boundaries before copying data into fixed-size buffers. This improper bounds checking allows an attacker to overflow the allocated memory space and potentially overwrite critical program execution data including return addresses and function pointers. The vulnerability is categorized under CWE-121 as a stack-based buffer overflow, which typically enables attackers to execute arbitrary code with the privileges of the affected process. The EXTRABACON moniker and Bug ID CSCva92151 reference the specific tracking identifiers used internally by Cisco to manage this security issue, highlighting the severity and complexity of the flaw.
The operational impact of this vulnerability extends beyond simple code execution, as it could enable attackers to gain full control over the affected ASA appliances. Once compromised, these devices could be used to perform man-in-the-middle attacks, redirect network traffic, disable security policies, or serve as a pivot point for further attacks within the network. The authenticated nature of the attack vector means that an attacker would need valid SNMP credentials, but these credentials are often default passwords or weakly configured access controls that can be easily compromised through various attack techniques. Network administrators may be unaware of the compromise since the attack could occur through legitimate SNMP management interfaces, making detection more challenging. This vulnerability directly impacts the CIA triad by compromising confidentiality, integrity, and availability of the network security infrastructure.
Mitigation strategies for CVE-2016-6366 should prioritize immediate patching of affected devices to the latest Cisco ASA software releases that contain the necessary security fixes. Organizations should implement network segmentation to limit SNMP access to only trusted management stations and disable SNMPv1 and SNMPv2c protocols in favor of the more secure SNMPv3. Network access controls should be configured to restrict SNMP traffic to authorized IP addresses and implement monitoring for unusual SNMP packet patterns. Security teams should conduct comprehensive vulnerability assessments to identify all instances of affected Cisco ASA devices within their network infrastructure and establish baseline configurations that disable unnecessary services. The implementation of intrusion detection systems capable of detecting anomalous SNMP traffic patterns can provide additional layers of defense. Organizations should also review and strengthen their SNMP credential management policies, ensuring that default credentials are changed and that access controls are properly configured according to the principle of least privilege. This vulnerability demonstrates the critical importance of maintaining current security patches and proper network segmentation as fundamental defensive measures against remote code execution threats.