CVE-2012-4659 in SSL VPN
Summary
by MITRE
The AAA functionality in the IPv4 SSL VPN implementations on Cisco Adaptive Security Appliances (ASA) 5500 series devices, and the ASA Services Module (ASASM) in Cisco Catalyst 6500 series devices, with software 8.2 before 8.2(5.30) and 8.3 before 8.3(2.34) allows remote attackers to cause a denial of service (device reload) via a crafted authentication response, aka Bug ID CSCtz04566.
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Analysis
by VulDB Data Team • 04/18/2021
The vulnerability identified as CVE-2012-4659 represents a critical denial of service flaw within Cisco's Adaptive Security Appliances and Catalyst 6500 series devices that implement IPv4 SSL VPN functionality. This weakness specifically affects the Authentication, Authorization, and Accounting (AAA) implementation in the affected software versions, creating a pathway for remote attackers to disrupt network operations through carefully crafted authentication responses. The vulnerability impacts Cisco ASA 5500 series devices and the ASA Services Module (ASASM) in Catalyst 6500 series, making it a significant concern for enterprise networks relying on these security appliances for remote access control.
The technical flaw stems from insufficient input validation within the AAA processing mechanism of the SSL VPN implementation. When the affected devices receive a maliciously crafted authentication response, the system fails to properly handle the malformed data during the authentication process, leading to a complete device reload or system crash. This occurs because the device's AAA subsystem lacks proper bounds checking and error handling for specific authentication response fields, allowing attackers to exploit this weakness without requiring authentication credentials. The vulnerability is classified as a buffer overflow condition according to CWE-121, where insufficient memory protection mechanisms allow attackers to manipulate system behavior through malformed inputs.
The operational impact of this vulnerability is severe as it enables remote attackers to perform denial of service attacks against critical network infrastructure components. Organizations utilizing affected Cisco ASA and ASASM devices face the risk of unauthorized service disruption, potentially affecting remote access capabilities for legitimate users and compromising business continuity. The device reload caused by this vulnerability creates temporary network outages that can last several minutes while the system recovers, potentially disrupting critical business operations. This weakness particularly affects enterprises that rely heavily on SSL VPN connectivity for remote worker access, making it an attractive target for attackers seeking to disrupt business operations or create cover for other malicious activities.
Mitigation strategies for CVE-2012-4659 primarily involve applying the official Cisco security patches and updates that address the specific input validation issues within the AAA implementation. Network administrators should immediately upgrade affected devices to software versions 8.2(5.30) or later for software 8.2 releases, and 8.3(2.34) or later for software 8.3 releases. Additionally, implementing network segmentation and access controls can help reduce the attack surface by limiting direct network access to vulnerable devices. Organizations should also monitor network traffic for suspicious authentication patterns and implement intrusion detection systems to identify potential exploitation attempts. This vulnerability aligns with ATT&CK technique T1499.002 for network denial of service attacks and represents a classic example of how improper input validation can lead to system instability. The remediation process should include thorough testing of updated software in non-production environments before deployment to ensure compatibility with existing network configurations and services.