CVE-2001-1202 in Delegate
Summary
by MITRE
Cross-site scripting vulnerability in DeleGate 7.7.0 and 7.7.1 does not quote scripting commands within a "403 Forbidden" error page, which allows remote attackers to execute arbitrary Javascript on other clients via a URL that generates an error.
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Analysis
by VulDB Data Team • 12/21/2024
The vulnerability described in CVE-2001-1202 represents a classic cross-site scripting flaw within the DeleGate proxy server software version 7.7.0 and 7.7.1. This issue specifically manifests in the error handling mechanism of the proxy server when processing requests that result in a 403 Forbidden response. The core technical flaw lies in how DeleGate processes and displays user-supplied input within the error page context, failing to properly sanitize or quote scripting commands that are embedded within the HTTP response. When a client makes a request that triggers a forbidden access response, the server constructs an error page that includes the original URL or request parameters without adequate input validation or output encoding. This omission creates an exploitable condition where malicious actors can inject arbitrary javascript code into the error page that gets executed in the context of other users who view the page.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform various malicious activities through the compromised proxy server. The flaw allows remote code execution in the browser context of other users, potentially leading to session hijacking, credential theft, or redirection to malicious sites. According to CWE classification, this vulnerability maps to CWE-79 which specifically addresses Cross-site Scripting flaws, and more precisely to CWE-74 which deals with Improper Neutralization of Special Elements in Output Used by a Downstream Component. The attack vector operates through the standard HTTP protocol where an attacker crafts a malicious URL that when processed by the vulnerable DeleGate server generates a 403 error page containing unescaped javascript code. When other users access this error page, their browsers execute the embedded javascript, providing the attacker with a means to compromise those users' sessions or browser environments.
This vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to initial access and execution phases. The attack begins with the attacker identifying the vulnerable proxy server and crafting malicious requests that trigger the specific error condition. The execution phase occurs when other users browse to the malicious error page, causing their browsers to execute the injected javascript code. The impact is significant as it allows attackers to leverage the proxy server's legitimate functionality to deliver malicious payloads to unsuspecting users, effectively using the server as a vector for attack. Organizations using DeleGate proxy servers in environments where users may encounter untrusted URLs are particularly vulnerable to this type of attack, as the flaw can be exploited without requiring authentication or privileged access to the proxy server itself. The remediation strategy involves implementing proper input validation and output encoding mechanisms within the error handling code, ensuring that all user-supplied data is properly escaped or quoted before inclusion in error messages. This approach aligns with the principle of defense in depth and follows established security practices for preventing XSS vulnerabilities in web applications and proxy server implementations.