CVE-2009-4914 in ASA 5580
Summary
by MITRE
Memory leak on Cisco Adaptive Security Appliances (ASA) 5580 series devices with software before 8.1(2) allows remote attackers to cause a denial of service (memory consumption) via Subject Alternative Name fields in an X.509 certificate, aka Bug ID CSCsq17879.
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Analysis
by VulDB Data Team • 04/20/2017
The vulnerability identified as CVE-2009-4914 affects Cisco Adaptive Security Appliances (ASA) 5580 series devices running software versions prior to 8.1(2). This memory leak vulnerability specifically targets the handling of X.509 certificates within the SSL VPN functionality of these security appliances. The flaw manifests when the ASA device processes Subject Alternative Name (SAN) fields contained within X.509 certificates, creating a condition where memory consumption gradually increases without proper cleanup. This represents a classic denial of service vulnerability that can be exploited remotely by attackers who possess the ability to present malicious certificates to the affected appliances.
The technical root cause of this vulnerability lies in the improper memory management within the SSL VPN certificate processing routines of the Cisco ASA software. When the device encounters X.509 certificates containing Subject Alternative Name fields, the system fails to properly release allocated memory resources after processing these certificate components. This memory leak occurs repeatedly with each certificate presented to the appliance, causing progressive memory exhaustion over time. The vulnerability is categorized under CWE-401 as a failure to release memory resources, which directly maps to the memory management flaw in the certificate processing code. The attack vector is remote, meaning that an unauthenticated attacker can trigger this condition from outside the network perimeter by establishing SSL VPN connections with specially crafted certificates.
The operational impact of CVE-2009-4914 is significant for organizations relying on Cisco ASA 5580 series appliances for their network security infrastructure. Once exploited, the vulnerability leads to gradual memory exhaustion on the affected devices, ultimately resulting in complete denial of service for SSL VPN services. Network administrators may observe performance degradation, application timeouts, and complete service outages as the appliance's memory resources become depleted. The vulnerability affects the availability aspect of the CIA triad, specifically targeting the availability of SSL VPN services that many organizations depend upon for remote access. According to ATT&CK framework, this vulnerability maps to the T1499.004 technique related to network denial of service, where attackers exploit software flaws to exhaust system resources. The impact extends beyond simple service disruption as it can affect business continuity and remote workforce access capabilities, particularly in enterprises where SSL VPN is a critical component of their remote access strategy.
Organizations should implement immediate mitigations including upgrading to Cisco ASA software version 8.1(2) or later, which contains the necessary patches to address this memory leak vulnerability. Network administrators should also consider implementing certificate validation policies that limit the size and complexity of certificates accepted by the ASA devices, particularly focusing on Subject Alternative Name fields that may contain excessive or malformed data. The remediation process should include thorough testing of the updated software in non-production environments before deployment to ensure compatibility with existing network configurations. Additionally, monitoring should be implemented to detect unusual memory consumption patterns on ASA devices, which could indicate exploitation attempts. Organizations should also consider implementing network segmentation and access controls to limit the exposure of vulnerable ASA appliances to potential attackers. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date security firmware and the need for continuous vulnerability assessment and management programs to protect enterprise network infrastructure from similar memory management flaws.