CVE-2007-4319 in Zywall 2
Summary
by MITRE
The management interface in ZyNOS firmware 3.62(WK.6) on the Zyxel Zywall 2 device allows remote authenticated administrators to cause a denial of service (infinite reboot loop) via invalid configuration data. NOTE: this issue might not cross privilege boundaries, and it might be resultant from CSRF; if so, then it should not be included in CVE.
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Analysis
by VulDB Data Team • 10/31/2017
The vulnerability described in CVE-2007-4319 affects the ZyNOS firmware version 3.62(WK.6) running on Zyxel Zywall 2 network security devices. This represents a significant security flaw in the device's management interface that could be exploited to disrupt service availability. The vulnerability specifically targets authenticated administrators who have access to the device's management functions, creating a potential vector for denial of service attacks that could render the network security appliance completely inoperable.
The technical flaw manifests through the management interface's inadequate validation of configuration data submitted by authenticated administrators. When invalid or malformed configuration parameters are processed, the system enters an infinite reboot loop, effectively causing a denial of service condition that prevents legitimate network traffic from being properly filtered and secured. This behavior indicates a lack of proper input sanitization and error handling within the firmware's configuration processing modules. The vulnerability falls under the category of improper input validation as classified by CWE-20, where the system fails to properly validate or sanitize user-supplied data before processing it.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network security infrastructure. When a Zywall 2 device enters an infinite reboot loop, it removes the network from its protective security functions, leaving the network segment it protects vulnerable to various cyber threats. This creates a cascading effect where network administrators lose visibility into their security posture and may be unable to respond to active threats. The vulnerability particularly affects organizations relying on Zyxel Zywall 2 devices for perimeter security, as the device's primary function becomes compromised, potentially allowing attackers to bypass network security controls.
Security researchers have noted that this vulnerability may not cross privilege boundaries, suggesting it might be a result of cross-site request forgery rather than a direct privilege escalation issue. This classification aligns with ATT&CK technique T1499.004 which covers network denial of service attacks. The potential CSRF nature of this vulnerability indicates that it might be triggered through web-based attacks where an attacker could craft malicious requests that exploit the authenticated administrator's session. Organizations should consider implementing additional security measures such as CSRF tokens and proper session management to prevent unauthorized configuration changes.
Mitigation strategies for this vulnerability should include immediate firmware updates to patched versions that properly validate configuration data and implement robust error handling mechanisms. Network administrators should also implement monitoring solutions that can detect unusual reboot patterns and alert security teams to potential exploitation attempts. Additionally, organizations should review their access control policies to ensure that only trusted administrators have access to the management interface, and implement multi-factor authentication where possible. The vulnerability demonstrates the importance of secure coding practices and proper input validation in firmware development, particularly for network security appliances where reliability and availability are critical factors in maintaining network security posture.