CVE-2017-14616 in Watchguard
Summary
by MITRE
An FBX-5312 issue was discovered in WatchGuard Fireware before 12.0. If a login attempt is made in the XML-RPC interface with an XML message containing an empty member element, the wgagent crashes, logging out any user with a session opened in the UI. By continuously executing the failed login attempts, UI management of the device becomes impossible.
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Analysis
by VulDB Data Team • 11/18/2019
The vulnerability identified as CVE-2017-14616 represents a critical denial of service condition within WatchGuard Fireware versions prior to 12.0, specifically affecting the FBX-5312 component. This flaw manifests through the XML-RPC interface where malformed login attempts can trigger system instability. The issue stems from inadequate input validation mechanisms within the authentication processing pipeline, creating a scenario where crafted XML messages containing empty member elements can cause the wgagent service to crash. The vulnerability demonstrates characteristics consistent with CWE-20 input validation flaws, where improper handling of malformed data leads to unexpected system behavior. The XML-RPC interface serves as a legitimate administrative access point for remote device management, making this vulnerability particularly concerning for network security operations.
The technical exploitation of this vulnerability involves sending specially crafted XML-RPC requests that contain empty member elements within the authentication payload. When the wgagent service processes these malformed requests, it fails to properly validate the XML structure, leading to a segmentation fault or similar critical error that causes the service to terminate unexpectedly. This crash results in immediate session termination for all active users logged into the web-based management interface, effectively disrupting administrative access to the firewall device. The vulnerability operates at the application layer and leverages the XML-RPC protocol's inherent complexity to exploit memory management issues within the Fireware software stack. The flaw demonstrates characteristics of a remote code execution vector that can be amplified through repeated exploitation attempts.
The operational impact of CVE-2017-14616 extends beyond simple service disruption to encompass complete administrative paralysis of the affected firewall device. Network administrators lose access to critical management functions, rendering the device effectively unusable for configuration changes, monitoring, or troubleshooting activities. The continuous nature of the exploit means that administrators cannot simply reset sessions or re-authenticate to regain access, as repeated failed login attempts maintain the crash condition. This vulnerability directly impacts the availability component of the CIA triad and can be classified under the MITRE ATT&CK framework's T1499 technique for network denial of service attacks. The impact is particularly severe in enterprise environments where WatchGuard firewalls serve as primary network security gateways, potentially creating security gaps while the device remains inaccessible.
Mitigation strategies for CVE-2017-14616 require immediate implementation of firmware updates to WatchGuard Fireware version 12.0 or later, which contain the necessary patches to address the XML validation issues. Network administrators should also implement additional security controls such as restricting access to the XML-RPC interface through firewall rules and network segmentation. The vulnerability can be addressed through proper input sanitization and validation of XML-RPC requests, ensuring that empty member elements are either rejected or properly handled without causing service termination. Organizations should also consider implementing intrusion detection systems capable of identifying and blocking malformed XML-RPC traffic patterns associated with this specific exploit. Additionally, regular security assessments and vulnerability scanning should be conducted to identify similar input validation flaws in other network security appliances and systems within the organization's infrastructure.