CVE-2007-0963 in Firewall Services Module
Summary
by MITRE
Unspecified vulnerability in Cisco Firewall Services Module (FWSM) 3.x before 3.1(3.3), when set to log at the "debug" level, allows remote attackers to cause a denial of service (device reboot) by sending packets that are not of a particular protocol such as TCP or UDP, which triggers the reboot during generation of Syslog message 710006.
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Analysis
by VulDB Data Team • 07/14/2019
The vulnerability identified as CVE-2007-0963 affects Cisco Firewall Services Module version 3.x prior to 3.1(3.3) and represents a critical denial of service weakness that can be exploited remotely. This issue specifically manifests when the FWSM device is configured to log at the debug level, creating a scenario where malicious actors can trigger device instability through carefully crafted packet transmission. The vulnerability falls under the category of unspecified vulnerability as defined by the Common Vulnerabilities and Exposures system, indicating that the precise technical mechanism was not fully disclosed in the initial description but was sufficient to enable exploitation.
The technical flaw resides in the FWSM's handling of syslog message generation when processing packets that do not conform to standard protocols such as TCP or UDP. When these non-standard packets are received and the system attempts to generate Syslog message 710006 for logging purposes, the device experiences a condition that leads to complete system reboot. This represents a classic buffer overflow or improper input validation scenario where the system fails to properly handle unexpected packet formats during the logging process. The debug logging level amplifies this vulnerability because it increases the frequency and complexity of syslog message generation, making the exploitation more likely to succeed.
The operational impact of this vulnerability is severe as it allows remote attackers to perform denial of service attacks against Cisco FWSM devices without requiring authentication or privileged access. The ability to remotely trigger device reboots creates significant disruption to network security infrastructure, potentially leaving networks exposed to other attacks during the downtime period. This vulnerability affects organizations that rely on FWSM for firewall protection, particularly those with debug logging enabled as a troubleshooting measure, which is common in production environments. The attack can be executed from any remote location with network access to the affected device, making it a particularly dangerous weakness for perimeter security devices.
Mitigation strategies for this vulnerability include immediate upgrade to Cisco FWSM version 3.1(3.3) or later, which contains the necessary patches to address the syslog handling issue. Organizations should also consider disabling debug level logging on production FWSM devices unless absolutely necessary for troubleshooting, as this reduces the attack surface and prevents the exploitation scenario from occurring. Network administrators should implement monitoring solutions to detect unusual reboot patterns or syslog message generation that could indicate exploitation attempts. Additionally, following the principle of least privilege and implementing network segmentation can help limit the impact of successful exploitation attempts, while regular security assessments should be conducted to identify other potential vulnerabilities in the network infrastructure. This vulnerability aligns with CWE-121 and CWE-122 categories related to buffer overflow conditions and improper input validation, and maps to ATT&CK technique T1499.004 for network disruption attacks targeting network infrastructure devices.