CVE-2000-0787 in X-Chat
Summary
by MITRE
IRC Xchat client versions 1.4.2 and earlier allows remote attackers to execute arbitrary commands by encoding shell metacharacters into a URL which XChat uses to launch a web browser.
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Analysis
by VulDB Data Team • 12/20/2024
The vulnerability identified as CVE-2000-0787 represents a critical command injection flaw within the XChat IRC client version 1.4.2 and earlier. This security weakness stems from inadequate input validation and sanitization when processing URLs that the client uses to launch web browsers. The vulnerability operates at the application layer and demonstrates a classic example of improper input handling that can be exploited by remote attackers to execute arbitrary commands on the affected system.
The technical flaw manifests when XChat processes URLs contained within IRC messages or other network communications. The client fails to properly sanitize or escape special shell metacharacters present in URLs before passing them to the underlying operating system for browser execution. This occurs because the application directly incorporates user-supplied URL data into system commands without appropriate validation or encoding mechanisms. Attackers can craft malicious URLs containing shell operators such as semicolons, ampersands, or backticks that get interpreted by the system shell when the browser is launched. This vulnerability maps to CWE-78 which specifically addresses OS command injection flaws in software applications.
The operational impact of this vulnerability is severe as it provides remote attackers with arbitrary code execution capabilities on systems running vulnerable XChat versions. An attacker who gains access to an IRC channel where XChat is used can simply send a specially crafted URL message that, when clicked or automatically processed by the client, executes malicious commands on the target system. This could lead to complete system compromise, data exfiltration, or the installation of backdoors. The attack requires minimal privileges since the exploit works against the client itself rather than requiring network-level access to the system. From an adversary perspective, this vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation through application layer attacks.
Mitigation strategies for this vulnerability include immediate patching of XChat to versions that properly sanitize URL inputs before browser execution. Organizations should implement network segmentation to limit IRC access to trusted users and systems. Input validation controls should be implemented at the application level to escape or remove dangerous shell metacharacters from URLs. Additionally, users should be educated about the risks of clicking untrusted URLs in IRC communications. System administrators should consider implementing network-level firewalls to restrict IRC traffic or deploy intrusion detection systems that monitor for suspicious URL patterns. The vulnerability serves as a prime example of why proper input validation and secure coding practices are essential in client applications that interact with operating system functions, particularly those involving user-supplied data processing and shell command execution.