CVE-2007-0964 in Firewall Services Module
Summary
by MITRE
Cisco FWSM 3.x before 3.1(3.18), when authentication is configured to use "aaa authentication match" or "aaa authentication include", allows remote attackers to cause a denial of service (device reboot) via a malformed HTTPS request.
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Analysis
by VulDB Data Team • 07/14/2019
The vulnerability identified as CVE-2007-0964 affects Cisco Firewall Services Module version 3.x prior to 3.1(3.18) and represents a critical denial of service flaw that can be exploited remotely by attackers to reboot affected devices. This vulnerability specifically manifests when the firewall is configured to use either "aaa authentication match" or "aaa authentication include" authentication methods, which are standard authentication mechanisms within Cisco's security infrastructure. The flaw demonstrates how improper input validation in the processing of secure communication protocols can lead to system instability and complete service disruption.
The technical root cause of this vulnerability lies in the insufficient validation of HTTPS request parameters within the authentication processing pipeline of the FWSM. When a malformed HTTPS request is crafted and sent to the device, it triggers an unhandled exception in the authentication module that manages the aaa authentication match and include configurations. This occurs because the system fails to properly sanitize or validate the incoming request data before processing it through the authentication framework, leading to a buffer overflow condition or stack corruption that ultimately results in the device crashing and rebooting. The vulnerability operates at the application layer of the network stack and requires no authentication to exploit, making it particularly dangerous for network administrators who may not be aware of the specific authentication configurations in use.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network security posture and availability. Organizations relying on Cisco FWSM appliances for network security filtering and access control may experience unexpected downtime, especially during peak network usage periods when the device is under heavy authentication load. The vulnerability affects the fundamental availability of the firewall service, potentially leaving network segments unprotected during the reboot process and creating windows of exposure for other attack vectors. Network administrators may also face challenges in maintaining audit trails and security monitoring capabilities during the device reboots, as the system's logging mechanisms may be disrupted by the crash conditions.
Mitigation strategies for CVE-2007-0964 primarily focus on immediate software updates and configuration adjustments to prevent exploitation. The most effective remediation involves upgrading the FWSM software to version 3.1(3.18) or later, which includes patches addressing the input validation flaws in the authentication processing modules. Organizations should also implement network segmentation and access controls to limit exposure of vulnerable devices to untrusted networks, while monitoring for unusual authentication request patterns that may indicate attempted exploitation. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of how authentication mechanisms can become attack vectors when not properly validated. From an ATT&CK perspective, this vulnerability maps to the T1499.004 technique for network denial of service, and the T1566.001 technique for credential access through exploitation of authentication services. Network security teams should also consider implementing intrusion detection systems that can identify malformed HTTPS requests and alert administrators to potential exploitation attempts, while maintaining detailed logging of authentication events to detect anomalous behavior patterns.