CVE-2010-4679 in ASA
Summary
by MITRE
Cisco Adaptive Security Appliances (ASA) 5500 series devices with software before 8.2(3) do not properly handle Online Certificate Status Protocol (OCSP) connection failures, which allows remote OCSP responders to cause a denial of service (TCP socket exhaustion) by rejecting connection attempts, aka Bug ID CSCsz36816.
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Analysis
by VulDB Data Team • 11/30/2024
The vulnerability described in CVE-2010-4679 represents a critical flaw in Cisco Adaptive Security Appliances (ASA) 5500 series devices running software versions prior to 8.2(3). This issue specifically targets the handling of Online Certificate Status Protocol (OCSP) connections within the security appliance's certificate validation process. The flaw stems from inadequate error handling mechanisms that fail to properly manage connection failures when communicating with OCSP responders, creating a potential avenue for remote attackers to exploit the system's resource management capabilities.
The technical implementation of this vulnerability occurs when the ASA device attempts to validate SSL/TLS certificates through OCSP requests to external responders. When an OCSP responder rejects connection attempts or fails to respond appropriately, the ASA device does not properly terminate or recycle the TCP connections that were established for this purpose. This improper connection handling leads to a gradual exhaustion of available TCP sockets within the device's connection pool, ultimately resulting in a denial of service condition that prevents legitimate network traffic from being processed.
From an operational impact perspective, this vulnerability creates a significant risk for organizations relying on Cisco ASA 5500 series appliances for network security. The TCP socket exhaustion attack can effectively render the security appliance non-functional, disrupting network connectivity and potentially exposing the organization to further security threats. The attack requires minimal resources from the attacker, as they only need to configure an OCSP responder to reject connection attempts, making this a particularly dangerous vulnerability that can be exploited without extensive technical expertise. The vulnerability affects the device's ability to perform certificate validation, which is a fundamental security function for SSL/TLS traffic inspection and secure communications.
Organizations affected by this vulnerability should prioritize immediate remediation through software updates to Cisco ASA software version 8.2(3) or later, which includes proper handling of OCSP connection failures and prevents the TCP socket exhaustion condition. Additional mitigations may include implementing network access controls to limit connections to known OCSP responders, configuring connection rate limiting, and establishing monitoring for unusual connection patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-400, which addresses improper handling of resources, and relates to ATT&CK technique T1499.004 for network disruption attacks. Security teams should also consider implementing intrusion detection systems to monitor for patterns consistent with TCP socket exhaustion attacks and establish incident response procedures for handling potential exploitation attempts targeting this specific vulnerability.