CVE-2024-41813 in txtdot
Summary
by MITRE • 07/26/2024
txtdot is an HTTP proxy that parses only text, links, and pictures from pages, removing ads and heavy scripts. Starting in version 1.4.0 and prior to version 1.6.1, a Server-Side Request Forgery (SSRF) vulnerability in the `/proxy` route of txtdot allows remote attackers to use the server as a proxy to send HTTP GET requests to arbitrary targets and retrieve information in the internal network. Version 1.6.1 patches the issue.
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Analysis
by VulDB Data Team • 09/30/2024
The txtdot HTTP proxy application presents a critical server-side request forgery vulnerability in its proxy functionality that enables remote attackers to exploit the system as an intermediary for unauthorized network communications. This vulnerability specifically affects versions 1.4.0 through 1.6.0 of the software, creating a significant security risk where attackers can leverage the proxy server to access internal network resources that would otherwise be protected from external exposure. The flaw exists within the `/proxy` route implementation, which fails to properly validate or sanitize user-provided URLs that are processed through the proxy mechanism, allowing malicious actors to craft requests that bypass normal network restrictions and gain unauthorized access to internal services.
The technical implementation of this vulnerability stems from inadequate input validation within the proxy routing logic, where the application accepts arbitrary URLs without proper sanitization or destination verification. Attackers can construct malicious requests that target internal network resources by manipulating the proxy endpoint to forward HTTP GET requests to internal systems, effectively using the txtdot server as a pivot point for reconnaissance and exploitation activities. This type of vulnerability falls under CWE-918, which specifically addresses server-side request forgery conditions where applications fail to properly validate or restrict access to internal resources through proxy mechanisms. The vulnerability enables attackers to potentially discover internal services, gather sensitive information, or even escalate their access to other internal systems that may be accessible through the compromised proxy server.
The operational impact of this SSRF vulnerability extends beyond simple information disclosure, as it provides attackers with the capability to perform internal network reconnaissance and potentially access sensitive systems that should remain isolated from external networks. Remote attackers can leverage this vulnerability to enumerate internal services, identify running applications, and gather intelligence about the internal network topology, which could facilitate further attacks or compromise of additional systems. The vulnerability is particularly dangerous in environments where internal services are not properly isolated from external access or where the proxy server has elevated privileges that could be exploited to access restricted resources. This vulnerability directly maps to ATT&CK technique T1071.004 for application layer protocol usage and T1018 for remote system discovery, making it a significant threat vector for attackers seeking to expand their access within compromised networks.
Organizations utilizing txtdot versions between 1.4.0 and 1.6.0 should immediately implement mitigations including updating to version 1.6.1 or later, which contains the necessary patches to address this vulnerability. Additional protective measures should include implementing proper input validation and URL sanitization within the proxy routing logic, restricting proxy functionality to known good destinations only, and monitoring proxy access logs for suspicious patterns. Network segmentation and firewall rules should be configured to prevent direct access to internal resources from the proxy server, while also implementing proper access controls and authentication mechanisms to limit who can utilize the proxy functionality. The vulnerability demonstrates the importance of proper input validation in web applications and highlights how seemingly benign proxy functionality can become a critical security weakness when proper security controls are not implemented.