CVE-2017-8056 in Firebox
Summary
by MITRE
WatchGuard Fireware v11.12.1 and earlier mishandles requests referring to an XML External Entity (XXE), in the XML-RPC agent. This causes the Firebox wgagent process to crash. This process crash ends all authenticated sessions to the Firebox, including management connections, and prevents new authenticated sessions until the process has recovered. The Firebox may also experience an overall degradation in performance while the wgagent process recovers. An attacker could continuously send XML-RPC requests that contain references to external entities to perform a limited Denial of Service (DoS) attack against an affected Firebox.
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Analysis
by VulDB Data Team • 12/02/2022
The vulnerability identified as CVE-2017-8056 represents a critical security flaw within WatchGuard Fireware versions 11.12.1 and earlier, specifically targeting the XML-RPC agent component. This issue stems from improper handling of XML External Entity (XXE) requests, which creates a significant attack surface that can be exploited to disrupt network security operations. The flaw manifests when the Firebox wgagent process encounters XML-RPC requests containing external entity references, leading to process instability and system-wide operational degradation.
The technical implementation of this vulnerability resides in the XML-RPC agent's failure to properly validate and sanitize XML input streams. When an attacker crafts malicious XML-RPC requests with external entity declarations, the agent processes these requests without adequate protection mechanisms, causing the wgagent process to crash. This crash represents a fundamental failure in input validation and resource management, as the system does not implement proper bounds checking or entity resolution controls. The vulnerability aligns with CWE-611, which specifically addresses improper restriction of XML external entity reference, making it a classic example of insecure XML processing that can lead to both denial of service and potential information disclosure.
The operational impact of this vulnerability extends beyond simple service disruption, creating cascading effects that compromise network management and security operations. When the wgagent process crashes, all authenticated sessions to the Firebox are terminated, including critical management connections that administrators rely upon for system oversight. This immediate session termination creates a window of vulnerability where network security cannot be effectively monitored or managed, potentially allowing other attacks to go undetected while the system recovers. The recovery process itself introduces additional performance degradation as the system attempts to stabilize, creating a prolonged period of reduced security posture that can be exploited by determined attackers.
The denial of service aspect of this vulnerability can be amplified through continuous exploitation, where attackers repeatedly send malformed XML-RPC requests to maintain system instability. This sustained attack pattern can prevent new authenticated sessions from being established until the wgagent process fully recovers, effectively creating a persistent availability issue that undermines the core function of the firewall appliance. The attack vector demonstrates how a single flawed component can compromise the entire security infrastructure, as the wgagent process serves as a critical daemon for various management functions within the WatchGuard Fireware ecosystem. Organizations implementing mitigations must consider both immediate patching strategies and broader network resilience measures to protect against this specific attack pattern that leverages XML processing weaknesses to achieve system disruption.
This vulnerability exemplifies the importance of implementing proper XML parsing security controls and demonstrates how seemingly minor implementation flaws can create significant operational security risks. The attack scenario highlights the need for comprehensive input validation across all XML processing components and emphasizes the critical nature of maintaining up-to-date security patches in network infrastructure devices. Organizations should implement monitoring solutions that can detect unusual XML-RPC traffic patterns and establish automated recovery procedures to minimize the impact of such attacks on network availability and security operations.