CVE-2013-3415 in ASA
Summary
by MITRE
Cisco Adaptive Security Appliance (ASA) Software 8.4.x before 8.4(3) and 8.6.x before 8.6(1.3) does not properly manage memory upon an AnyConnect SSL VPN client disconnection, which allows remote attackers to cause a denial of service (memory consumption, and forwarding outage or system hang) via packets to the disconnected machine s IP address, aka Bug ID CSCtt36737.
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Analysis
by VulDB Data Team • 05/26/2021
The vulnerability identified as CVE-2013-3415 affects Cisco Adaptive Security Appliance (ASA) software versions 8.4.x prior to 8.4(3) and 8.6.x prior to 8.6(1.3), representing a critical memory management flaw within the AnyConnect SSL VPN implementation. This issue stems from improper handling of memory resources when SSL VPN clients disconnect from the ASA device, creating a condition where the system fails to properly release allocated memory segments. The flaw manifests when remote attackers send specific packets to the IP address of a disconnected client, triggering a memory consumption pattern that can escalate to complete system unresponsiveness or forwarding outages. This vulnerability directly impacts the availability and operational integrity of network security infrastructure, as the ASA device becomes unable to process legitimate traffic while consuming excessive memory resources. The root cause aligns with CWE-400, which categorizes improper resource management as a fundamental weakness in software design that can lead to resource exhaustion and system instability. The memory management failure occurs at the application layer within the SSL VPN processing pipeline, where the device fails to properly invalidate session state information and release associated memory structures upon client disconnection.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it can effectively render the entire ASA appliance non-functional during the memory exhaustion event. When attackers exploit this weakness, they can cause the device to consume all available memory resources, leading to system hangs or complete service outages that affect all VPN connections and network traffic passing through the appliance. The vulnerability is particularly dangerous because it can be exploited remotely without requiring authentication or prior access to the network, making it a significant threat to organizations relying on ASA devices for secure remote access. Network administrators may experience extended downtime as the system becomes unresponsive, requiring manual intervention to reboot the appliance and restore normal operations. The attack vector involves sending crafted packets to the IP address of a disconnected VPN client, which triggers the memory leak condition through the ASA's packet processing mechanisms. This vulnerability demonstrates the importance of proper session state management and resource cleanup in network security appliances, as failure to address these conditions can result in complete system compromise.
Mitigation strategies for CVE-2013-3415 should prioritize immediate deployment of the applicable Cisco security patches, specifically versions 8.4(3) for 8.4.x releases and 8.6(1.3) for 8.6.x releases, which contain the necessary fixes to properly manage memory resources upon client disconnection. Organizations should implement network segmentation and access controls to limit exposure to potential attackers, while also monitoring for unusual memory consumption patterns that may indicate exploitation attempts. The implementation of intrusion detection systems can help identify the specific packet patterns used to exploit this vulnerability, allowing for proactive network defense measures. Security teams should also conduct regular vulnerability assessments to identify similar memory management issues in other network infrastructure components, as this vulnerability represents a common class of flaws that can affect various network security devices. From an operational perspective, maintaining detailed logging of VPN session activities and memory usage patterns enables administrators to quickly identify when the vulnerability is being exploited and respond appropriately. The remediation process should include thorough testing of the patched software in controlled environments before deployment to production systems, ensuring that the fixes do not introduce compatibility issues with existing network configurations. This vulnerability highlights the importance of maintaining current security patches and following the principle of least privilege in network security implementations, as the attack surface for such memory-related vulnerabilities continues to expand with increasingly complex network environments.