CVE-2011-3297 in Firewall Services Module Software
Summary
by MITRE
Cisco Firewall Services Module (aka FWSM) 3.1 before 3.1(21), 3.2 before 3.2(22), 4.0 before 4.0(16), and 4.1 before 4.1(7), when certain authentication configurations are used, allows remote attackers to cause a denial of service (module crash) by making many authentication requests for network access, aka Bug ID CSCtn15697.
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Analysis
by VulDB Data Team • 01/22/2018
The vulnerability described in CVE-2011-3297 affects Cisco Firewall Services Module implementations across multiple software versions including 3.1.x before 3.1(21), 3.2.x before 3.2(22), 4.0.x before 4.0(16), and 4.1.x before 4.1(7). This issue represents a significant security weakness that impacts network infrastructure devices critical to enterprise security operations. The vulnerability specifically manifests when certain authentication configurations are implemented within the FWSM environment, creating a condition where remote attackers can exploit the system through a specific type of denial of service attack.
The technical flaw stems from insufficient input validation and resource management within the authentication handling mechanisms of the FWSM module. When legitimate authentication requests are made in rapid succession or in large volumes, the system fails to properly manage these requests, leading to resource exhaustion and subsequent module instability. This behavior aligns with CWE-400, which classifies the vulnerability as a resource exhaustion condition where the system cannot properly handle the volume of incoming authentication requests. The attack vector involves sending numerous authentication requests to the target device, causing the module to consume excessive system resources until it becomes unresponsive and crashes.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network security posture and availability. Organizations relying on FWSM for network access control and firewall services face significant risks when this vulnerability is exploited, as the module crash would interrupt network connectivity and authentication services. This could affect critical business operations, particularly in environments where network access control is essential for security compliance. The vulnerability creates a condition where attackers can systematically disable network security services without requiring elevated privileges or specialized knowledge, making it particularly dangerous in enterprise environments.
Mitigation strategies should focus on immediate software updates to the affected versions, implementing rate limiting mechanisms to prevent excessive authentication requests, and monitoring network traffic for unusual patterns of authentication activity. Organizations should also consider implementing additional access controls and authentication throttling measures to protect against exploitation. The remediation process involves applying the relevant Cisco security patches and updates, which address the resource management issues within the authentication handling code. Network administrators should also review and test authentication configurations to ensure that the specific vulnerable setups are not in use, while implementing monitoring solutions that can detect and alert on potential exploitation attempts. This vulnerability demonstrates the importance of proper resource management in security infrastructure components and highlights the need for robust input validation and rate limiting mechanisms in authentication systems.