CVE-2009-4912 in ASA 5580
Summary
by MITRE
Cisco Adaptive Security Appliances (ASA) 5580 series devices with software before 8.1(2) complete an SSL handshake with an HTTPS client even if this client is unauthorized, which might allow remote attackers to bypass intended access restrictions via an HTTPS session, aka Bug ID CSCso10876.
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Analysis
by VulDB Data Team • 04/20/2017
The vulnerability described in CVE-2009-4912 represents a critical authentication bypass flaw within Cisco Adaptive Security Appliances version 5580 series devices running software versions prior to 8.1(2). This issue specifically affects the SSL/TLS implementation within the ASA's secure socket layer handling mechanism, creating a pathway for unauthorized remote attackers to establish legitimate HTTPS sessions without proper authorization. The flaw exists in the device's certificate validation and session establishment process, where the system fails to properly enforce access controls during the SSL handshake phase.
The technical implementation of this vulnerability stems from insufficient validation of client certificates and authentication credentials during the SSL handshake completion process. When an HTTPS client attempts to establish a connection to the ASA device, the system erroneously completes the SSL handshake regardless of whether the client has been properly authenticated or authorized to access the protected resources. This behavior violates fundamental security principles of access control and authentication enforcement that should occur before any secure communication channel is established. The vulnerability operates at the application layer of the OSI model, specifically within the transport layer security protocols that govern secure web communications.
From an operational impact perspective, this vulnerability creates significant risk for organizations relying on Cisco ASA 5580 series devices for network security. Remote attackers can exploit this flaw to bypass access restrictions that should normally prevent unauthorized access to internal resources, potentially gaining access to sensitive data, systems, and network segments that would otherwise be protected by the ASA's access control policies. The attack vector is particularly concerning as it requires no local access or specialized equipment beyond standard network connectivity to an HTTPS endpoint. This vulnerability directly impacts the CIA triad by potentially compromising confidentiality and integrity of network communications, as unauthorized parties can establish secure connections and potentially intercept or manipulate data flows.
The flaw aligns with CWE-287, which addresses improper authentication issues in security systems, and represents a classic case of weak session management where authentication checks are bypassed during connection establishment. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and initial access through network service exploitation, specifically targeting the T1190 - Exploit Public-Facing Application and T1078 - Valid Accounts categories. Organizations may face compliance violations under various regulatory frameworks including pci dss, hipaa, and soc 2, as this vulnerability creates potential data exposure pathways that could result in significant regulatory penalties.
Mitigation strategies for this vulnerability include immediate deployment of Cisco's recommended software updates to version 8.1(2) or later, which contain patches addressing the SSL handshake authentication bypass. Network administrators should also implement additional monitoring and logging of SSL/TLS connections to detect anomalous behavior patterns that might indicate exploitation attempts. Configuration hardening measures such as implementing stricter certificate validation policies, disabling unnecessary SSL/TLS versions, and enforcing robust access control lists should be considered as additional defensive layers. Organizations should conduct thorough security assessments to identify any potential exploitation that may have occurred prior to patching and implement network segmentation to limit the potential impact of successful attacks. The vulnerability underscores the importance of maintaining current security software versions and implementing comprehensive network monitoring solutions to detect and respond to such authentication bypass attacks effectively.