CVE-2016-8726 in AWK-3131A
Summary
by MITRE
An exploitable null pointer dereference vulnerability exists in the Web Application /forms/web_runScript iw_filename functionality of Moxa AWK-3131A Wireless Access Point running firmware 1.1. An HTTP POST request with a blank line in the header will cause a segmentation fault in the web server.
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Analysis
by VulDB Data Team • 11/29/2022
The CVE-2016-8726 vulnerability represents a critical null pointer dereference flaw within the Moxa AWK-3131A Wireless Access Point firmware version 1.1. This vulnerability specifically affects the web application's /forms/web_runScript functionality, which handles the iw_filename parameter. The issue manifests when processing HTTP POST requests that contain a blank line in the header section, leading to a segmentation fault that crashes the web server component. This type of vulnerability falls under the CWE-476 category of Null Pointer Dereference, where the application fails to properly validate input parameters before attempting to access memory locations. The vulnerability demonstrates a fundamental flaw in input sanitization and error handling within the web server's request processing pipeline, creating a potential denial of service condition that can be exploited by remote attackers without authentication requirements.
The technical exploitation of this vulnerability occurs through a carefully crafted HTTP POST request that includes a blank line within the request headers. When the web server processes this malformed request, it attempts to parse the iw_filename parameter without proper validation, resulting in a null pointer dereference that ultimately causes a segmentation fault. This segmentation fault terminates the web server process, effectively rendering the device inaccessible to legitimate users and potentially providing an attacker with a means to disrupt network services. The vulnerability's impact extends beyond simple service disruption as it can be leveraged to achieve persistent denial of service conditions, particularly in environments where continuous network availability is critical. The flaw demonstrates poor defensive programming practices and inadequate input validation mechanisms that fail to properly handle edge cases in HTTP request parsing.
From an operational perspective, this vulnerability poses significant risks to network infrastructure security, particularly for organizations relying on Moxa AWK-3131A devices for wireless access control. The remote exploitability without authentication requirements means that attackers can potentially target these devices from outside the network perimeter, making them attractive targets for malicious actors seeking to disrupt operations or create backdoor access points. The segmentation fault behavior can be reliably reproduced through automated tools, making this vulnerability particularly dangerous in large-scale deployment scenarios where multiple devices may be affected simultaneously. Network administrators face the challenge of identifying vulnerable devices within their infrastructure and implementing immediate mitigations while planning for proper firmware updates, as the vulnerability exists in a device's core web server functionality that is essential for device management and configuration.
The mitigation strategies for CVE-2016-8726 primarily involve firmware updates from Moxa to address the null pointer dereference issue in the web server component. Organizations should also implement network segmentation to limit access to these devices to trusted administrative networks only, reducing the attack surface available to potential exploiters. Additionally, implementing intrusion detection systems that can identify malformed HTTP requests containing blank lines in headers may provide early warning of attempted exploitation. Security monitoring should include regular vulnerability scanning of network devices to identify unpatched systems running affected firmware versions. The ATT&CK framework categorizes this vulnerability under the T1210 technique of Exploitation of Remote Services, while the CWE classification of 476 emphasizes the need for robust input validation and error handling in web application development practices. Organizations should also consider implementing web application firewalls to filter out malformed HTTP requests and establish incident response procedures to address potential exploitation attempts.