CVE-2007-0966 in Firewall Services Module
Summary
by MITRE
Cisco Firewall Services Module (FWSM) 3.x before 3.1(3.11), when the HTTPS server is enabled, allows remote attackers to cause a denial of service (device reboot) via certain HTTPS traffic.
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Analysis
by VulDB Data Team • 07/14/2019
The vulnerability identified as CVE-2007-0966 affects Cisco Firewall Services Module FWSM version 3.x prior to 3.1(3.11) where the HTTPS server functionality is enabled. This represents a critical security flaw that could potentially allow remote attackers to execute a denial of service attack against the affected device. The vulnerability specifically manifests when the HTTPS server component is active, creating an attack surface that adversaries can exploit to disrupt normal operations. The root cause lies in how the FWSM processes certain HTTPS traffic patterns that trigger an unexpected device reboot. This issue demonstrates a fundamental flaw in input validation and error handling mechanisms within the HTTPS server implementation. The vulnerability has significant implications for network security infrastructure as firewalls serve as critical components in protecting enterprise networks from external threats. When compromised, such devices can leave organizations vulnerable to both immediate service disruption and potential subsequent attacks due to the loss of network protection capabilities.
The technical exploitation of this vulnerability occurs through carefully crafted HTTPS traffic that triggers a buffer overflow or memory corruption condition within the FWSM's HTTPS server process. When the device receives this malformed traffic, it fails to properly handle the incoming data and subsequently reboots the entire system. This behavior aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. The attack vector is remote and does not require authentication, making it particularly dangerous as any network-connected attacker can potentially exploit this flaw. The vulnerability impacts the availability aspect of the CIA triad by rendering the firewall services unavailable through deliberate system rebooting. The device's HTTPS server component lacks proper input sanitization mechanisms, allowing malicious data to bypass normal processing boundaries and cause system instability. This type of vulnerability is classified under the ATT&CK technique T1499.004, which covers network denial of service attacks, specifically targeting network infrastructure devices.
The operational impact of CVE-2007-0966 extends beyond simple service disruption to potentially compromise entire network security postures. Organizations relying on FWSM appliances for firewall protection face significant risks when this vulnerability exists in their environment, as the device becomes unavailable for its primary function of network traffic filtering and security enforcement. The automatic reboot process creates a window of vulnerability where network traffic flows may be unfiltered, exposing the network to potential attacks during the device recovery period. Network administrators must consider the cascading effects of such an attack, as the failure of a core firewall component can lead to broader network security failures. The vulnerability also impacts business continuity and disaster recovery planning, as organizations must account for potential device failures and the associated downtime. Additionally, the attack can be automated and scaled, allowing threat actors to target multiple devices simultaneously, amplifying the impact on large enterprise networks. The lack of authentication requirements for exploitation means that even unauthenticated attackers can cause significant operational disruption. Organizations should implement immediate mitigations including disabling the HTTPS server functionality when not required, applying security patches, and monitoring network traffic for suspicious HTTPS patterns that may indicate exploitation attempts. The vulnerability also highlights the importance of regular security assessments and vulnerability management programs to identify and remediate such issues before they can be exploited in production environments.