CVE-2016-5813 in PowerLink2
Summary
by MITRE
An issue was discovered in Visonic PowerLink2, all versions prior to October 2016 firmware release. When a specific URL to an image is accessed, the downloaded image carries with it source code used in the web server (INFORMATION EXPOSURE).
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/01/2020
The vulnerability identified as CVE-2016-5813 affects Visonic PowerLink2 security systems with firmware versions released before October 2016. This issue represents a critical information exposure vulnerability that fundamentally undermines the security posture of these devices. The flaw manifests when specific URLs are accessed to retrieve images, but the downloaded content contains source code from the underlying web server rather than the intended visual media. This represents a classic case of improper access control and inadequate input validation within the web application layer of the security system.
The technical implementation of this vulnerability stems from insufficient sanitization of user-supplied input parameters within the web server's image retrieval mechanism. When a user accesses a particular URL structure, the system fails to properly validate or filter the request parameters before serving content. This allows an attacker to manipulate the URL to request source code files instead of images, effectively bypassing the intended file access restrictions. The vulnerability falls under the CWE-200 category of Information Exposure, specifically demonstrating how improper handling of resource access can lead to sensitive data disclosure. The flaw operates at the application layer and represents a failure in the principle of least privilege, where the web server provides access to files beyond what should be permitted for normal image retrieval operations.
The operational impact of this vulnerability extends far beyond simple information disclosure, as it provides attackers with access to the complete source code of the web application running on the security system. This exposure creates significant risk for organizations relying on these devices for physical security management. Attackers can analyze the source code to identify additional vulnerabilities, understand the internal architecture of the security system, and potentially discover authentication mechanisms, database schemas, or other sensitive implementation details. The vulnerability enables an attacker to gain unauthorized access to the web server's file system through the image retrieval endpoint, potentially leading to full system compromise. According to ATT&CK framework, this vulnerability maps to T1083 (File and Directory Discovery) and T1213 (Data from Information Repositories) techniques, as it allows for systematic exploration of the system's information resources.
Mitigation strategies for CVE-2016-5813 require immediate firmware updates from Visonic to address the root cause of the vulnerability. Organizations should implement network segmentation to isolate these security devices from critical network segments and consider implementing web application firewalls to monitor and filter requests to image endpoints. Access controls should be strengthened to ensure that only authenticated users can access web-based interfaces, and all unnecessary services should be disabled on the affected devices. Regular security assessments should include checking for similar issues in other web applications, particularly those involving file retrieval mechanisms. The vulnerability highlights the importance of proper input validation and access control implementation in embedded web applications, as well as the need for regular security updates and vulnerability assessments in security infrastructure devices. Organizations should also establish monitoring procedures to detect unusual access patterns to web endpoints that might indicate exploitation attempts.