CVE-2016-8723 in AWK-3131A
Summary
by MITRE
An exploitable null pointer dereference exists in the Web Application functionality of Moxa AWK-3131A Wireless Access Point running firmware 1.1. Any HTTP GET request not preceded by an '/' will cause a segmentation fault in the web server. An attacker can send any of a multitude of potentially unexpected HTTP get requests to trigger this vulnerability.
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Analysis
by VulDB Data Team • 11/29/2022
The CVE-2016-8723 vulnerability represents a critical null pointer dereference flaw within the web application component of Moxa AWK-3131A Wireless Access Point devices. This vulnerability manifests specifically in the web server implementation when processing HTTP GET requests that lack proper path formatting with a leading forward slash character. The affected firmware version 1.1 contains a programming error that fails to properly validate incoming HTTP request paths, creating an exploitable condition that can be triggered by malformed requests. The vulnerability resides in the web server's request parsing logic where it attempts to dereference a null pointer when encountering HTTP GET requests that do not begin with the expected '/' character.
From a technical perspective, this vulnerability operates through a classic buffer management flaw that aligns with CWE-476, which describes null pointer dereference conditions. The web server component processes HTTP requests without adequate input sanitization, particularly focusing on path validation. When an HTTP GET request is received without the leading slash, the application's internal request handler fails to properly initialize or validate the request path variable before attempting to access it. This results in a segmentation fault that crashes the web server process, effectively causing a denial of service condition. The vulnerability is particularly concerning because it can be triggered through numerous variations of malformed HTTP GET requests, making it difficult to fully mitigate through simple input filtering approaches.
The operational impact of this vulnerability extends beyond simple denial of service to create potential security implications for network infrastructure devices. An attacker who successfully exploits this vulnerability can cause persistent service disruption to the wireless access point, potentially affecting network connectivity for connected devices. The vulnerability demonstrates a fundamental flaw in the device's web server implementation that violates secure coding practices and can be leveraged as a stepping stone for further exploitation attempts. Network administrators may find their wireless infrastructure devices rendered unavailable due to this vulnerability, creating operational challenges that could affect business continuity and network availability. The segmentation fault condition also provides potential opportunities for information disclosure or further exploitation depending on the system's response handling.
Mitigation strategies for CVE-2016-8723 should prioritize firmware updates from Moxa to address the underlying null pointer dereference condition. Organizations should implement network segmentation to isolate affected devices and monitor for exploitation attempts through network traffic analysis. The vulnerability's exploitation requires minimal technical skill, making it particularly dangerous as it can be triggered by automated scanning tools. Network security controls should include HTTP request validation rules that enforce proper path formatting and implement rate limiting to prevent abuse of the vulnerability. Additionally, implementing network-based intrusion detection systems can help identify exploitation attempts targeting this specific flaw. The vulnerability also highlights the importance of proper input validation and error handling in embedded web server implementations, aligning with ATT&CK technique T1210 for exploitation of vulnerabilities in network infrastructure devices. Organizations should consider implementing network access controls that limit direct access to management interfaces and ensure that any web-based management functions are properly secured through authentication and encryption mechanisms.