CVE-2016-8720 in AWK-3131A
Summary
by MITRE
An exploitable HTTP Header Injection vulnerability exists in the Web Application functionality of the Moxa AWK-3131A Wireless Access Point running firmware 1.1. A specially crafted HTTP request can inject a payload in the bkpath parameter which will be copied in to Location header of the HTTP response.
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Analysis
by VulDB Data Team • 11/29/2022
The CVE-2016-8720 vulnerability represents a critical HTTP header injection flaw in Moxa AWK-3131A Wireless Access Point firmware version 1.1. This vulnerability falls under the category of insecure input handling within web application components, specifically affecting the way the device processes HTTP requests. The flaw manifests when an attacker crafts a malicious HTTP request containing a specially formatted payload in the bkpath parameter, which then gets reflected into the Location header of the HTTP response. This type of vulnerability is particularly dangerous because it can be exploited to manipulate HTTP responses and potentially redirect users to malicious destinations.
The technical implementation of this vulnerability stems from improper sanitization of user-supplied input within the web application interface of the wireless access point. When the device receives an HTTP request with a crafted bkpath parameter, it fails to properly validate or escape the input before incorporating it into the Location header. This creates a classic path traversal and header injection scenario where attacker-controlled data flows directly into a critical HTTP response header. The Location header is typically used for HTTP redirects and is processed by web browsers and other HTTP clients, making this vulnerability particularly dangerous for session manipulation and cross-site scripting attacks. According to CWE standards, this corresponds to CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers, which specifically addresses the injection of carriage return and line feed characters into HTTP headers.
The operational impact of this vulnerability extends beyond simple header manipulation, as it enables several attack vectors including open redirect attacks, session hijacking, and potential phishing scenarios. An attacker could craft a malicious URL that, when clicked by an authenticated user, would redirect them to a malicious site while maintaining the appearance of legitimacy. This is particularly concerning for wireless access points that may be used in enterprise environments where users trust the network infrastructure. The vulnerability affects the device's authentication mechanisms and could allow attackers to bypass security controls, potentially leading to unauthorized access to the network. From an ATT&CK framework perspective, this vulnerability maps to T1566.001: Phishing, as it enables the creation of convincing malicious redirects, and T1071.004: Application Layer Protocol: DNS, since the redirect could potentially be used to bypass DNS-based security controls.
Mitigation strategies for CVE-2016-8720 should focus on input validation and output encoding at multiple levels. Network administrators should immediately update the firmware to the latest version provided by Moxa, as this vulnerability was likely addressed in subsequent releases. Additionally, implementing proper input validation on the bkpath parameter to reject or sanitize potentially malicious characters including carriage return and line feed sequences would prevent exploitation. Network segmentation and access controls should be implemented to limit exposure of the wireless access point to untrusted networks. Web application firewalls and intrusion detection systems should be configured to monitor for suspicious HTTP header patterns, particularly those containing CRLF sequences. Regular security assessments and penetration testing of network infrastructure components are essential to identify similar vulnerabilities in other devices within the network perimeter. The vulnerability demonstrates the critical importance of secure coding practices in embedded web applications and highlights the need for comprehensive input validation across all user-controllable parameters within network devices.