CVE-2012-2474 in ASA
Summary
by MITRE
Memory leak on Cisco Adaptive Security Appliances (ASA) 5500 series devices with software 8.2 through 8.4 allows remote authenticated users to cause a denial of service (memory consumption and blank response page) by using the clientless WebVPN feature, aka Bug ID CSCth34278.
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Analysis
by VulDB Data Team • 12/07/2021
The vulnerability described in CVE-2012-2474 represents a critical memory management flaw within Cisco Adaptive Security Appliances (ASA) 5500 series devices operating with software versions 8.2 through 8.4. This issue specifically affects the clientless WebVPN functionality, which allows remote authenticated users to exploit a memory leak condition that ultimately leads to denial of service. The vulnerability operates through the ASA's web-based virtual private network access mechanism, where legitimate users can establish connections to network resources without requiring dedicated client software. The flaw manifests when authenticated users leverage the clientless WebVPN feature to perform specific operations that trigger repeated memory allocation without proper deallocation, causing progressive memory consumption over time.
The technical implementation of this vulnerability involves the ASA software's handling of session management within the clientless WebVPN context. When authenticated users access the WebVPN portal and perform certain operations, the system allocates memory resources to process their requests but fails to properly release these resources upon completion of the session lifecycle. This memory allocation pattern creates a gradual accumulation of memory usage that eventually exhausts available system resources. The memory leak occurs in the software's processing of HTTP requests and session management components that are specifically designed to handle web-based VPN access. According to CWE classification, this vulnerability maps to CWE-401: Improper Release of Memory, which addresses the failure to properly release memory resources after use, leading to resource exhaustion conditions. The flaw demonstrates characteristics of a resource exhaustion attack pattern that can be categorized under ATT&CK technique T1499.004: Endpoint Denial of Service, as it targets the availability of network security services through memory consumption.
The operational impact of CVE-2012-2474 extends beyond simple service disruption to potentially compromise the overall security posture of networks relying on affected ASA devices. When the memory leak reaches critical levels, the ASA appliance begins to exhibit symptoms including blank response pages, service timeouts, and complete denial of access to the WebVPN functionality. Network administrators may observe gradual performance degradation before complete service failure occurs, making the vulnerability particularly dangerous as it can remain undetected for extended periods. The authenticated nature of the attack means that only users with valid credentials can exploit this vulnerability, but this requirement does not mitigate the risk since compromised accounts or insider threats could leverage this flaw. The memory consumption pattern typically results in the appliance becoming unresponsive to legitimate user requests while maintaining its operational state, creating a subtle but effective denial of service condition that can persist until manual intervention occurs through device reboot or configuration changes.
Mitigation strategies for CVE-2012-2474 focus primarily on applying Cisco's official security patches and updates that address the memory leak in the WebVPN implementation. Organizations should prioritize upgrading their ASA 5500 series devices to software versions that contain the fix for Bug ID CSCth34278, which typically involves updating to software releases that include proper memory management and session cleanup procedures. Network administrators should also implement monitoring solutions to track memory usage patterns on affected appliances, enabling early detection of the memory leak before it reaches critical levels. Additional defensive measures include implementing access controls to limit the number of concurrent WebVPN sessions, reducing the attack surface by disabling clientless WebVPN functionality when not required, and establishing regular maintenance procedures that include device reboot cycles to clear accumulated memory states. The vulnerability serves as a reminder of the importance of proper memory management in security appliances and highlights the need for comprehensive testing of authentication and session handling mechanisms. Organizations should also consider implementing network segmentation strategies that limit the impact of such vulnerabilities and maintain detailed inventory records of all ASA devices to ensure complete patch management coverage across their network infrastructure.