CVE-2017-16091 in xtalk
Summary
by MITRE
xtalk helps your browser talk to nodex, a simple web framework. xtalk is vulnerable to a directory traversal issue, giving an attacker access to the filesystem by placing "../" in the URL.
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Analysis
by VulDB Data Team • 02/15/2020
The xtalk library represents a communication bridge between web browsers and nodex web frameworks, facilitating data exchange and interaction between client-side and server-side components. This vulnerability stems from insufficient input validation within the library's URL parsing mechanism, creating a critical directory traversal flaw that directly impacts the security posture of applications relying on this component. The vulnerability specifically manifests when the library fails to properly sanitize user-supplied URL parameters, allowing malicious actors to exploit path traversal sequences.
The technical implementation of this vulnerability leverages standard directory traversal payloads using the "../" sequence, which enables attackers to navigate beyond the intended directory boundaries and access arbitrary files on the server's filesystem. This flaw exists at the application layer and can be exploited through HTTP requests that contain crafted path traversal sequences in the URL parameters. The vulnerability is classified as a path traversal issue under CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as directory traversal or path traversal attacks.
The operational impact of this vulnerability extends beyond simple file access, as it can potentially lead to complete system compromise when combined with other attack vectors. An attacker could leverage this vulnerability to read sensitive configuration files, access database credentials, retrieve source code, or even execute arbitrary commands if the web application has insufficient privilege separation. This type of vulnerability aligns with ATT&CK technique T1083 (File and Directory Discovery) and T1566 (Phishing) when combined with social engineering approaches to initially gain access to the vulnerable system.
Mitigation strategies for this vulnerability require immediate implementation of proper input validation and sanitization mechanisms within the xtalk library. Developers should implement strict path validation that rejects any input containing directory traversal sequences, employ whitelisting approaches for valid paths, and utilize secure coding practices that prevent arbitrary file access. Additionally, the library should implement proper access controls and privilege separation to limit the damage that can occur even if traversal attacks are successful. Security patches should be applied immediately to all affected versions of the xtalk library, and organizations should conduct comprehensive audits of their web applications to identify any other components that might be vulnerable to similar path traversal issues. The vulnerability highlights the importance of input validation and secure coding practices in web development frameworks, particularly those handling user-supplied data that could potentially be used to access the underlying filesystem.