CVE-2001-1241 in Un-CGI
Summary
by MITRE
Un-CGI 1.9 and earlier does not verify that a CGI script has the execution bits set before executing it, which allows remote attackers to execute arbitrary commands by directing Un-CGI to a document that begins with "#!" and the desired program name.
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Analysis
by VulDB Data Team • 05/31/2018
The vulnerability identified as CVE-2001-1241 affects Un-CGI versions 1.9 and earlier, representing a critical security flaw in web server configuration and CGI script execution handling. This issue stems from insufficient input validation and privilege verification mechanisms within the Un-CGI application, which operates as a CGI gateway for web servers. The vulnerability allows remote attackers to exploit a fundamental security oversight in how the system processes and executes CGI scripts without proper authorization checks.
The technical flaw resides in the absence of execution bit verification for CGI scripts within the Un-CGI framework. When a web server processes a request through Un-CGI, the application fails to validate whether the targeted script possesses the necessary execute permissions before attempting execution. This oversight creates a path for malicious actors to manipulate the system by crafting specific document requests that begin with the shebang sequence "#!" followed by a desired program name. The vulnerability directly maps to CWE-78, which describes improper neutralization of special elements used in OS commands, and represents a classic case of command injection through insecure script execution handling.
The operational impact of this vulnerability is severe and far-reaching for any system running affected versions of Un-CGI. Remote attackers can leverage this weakness to execute arbitrary commands on the target system with the privileges of the web server process, potentially leading to complete system compromise. The vulnerability enables attackers to bypass normal access controls and execute malicious code directly on the server, making it particularly dangerous for web applications that rely on CGI scripts for dynamic content generation. This weakness can be exploited to gain unauthorized access, escalate privileges, or perform other malicious activities that could result in data theft, system corruption, or service disruption.
Mitigation strategies for CVE-2001-1241 focus primarily on immediate remediation through software updates and configuration hardening. Organizations should upgrade to Un-CGI versions that address this vulnerability, as the fix typically involves implementing proper execution bit verification before script execution. System administrators should also implement strict file permission controls, ensuring that CGI scripts are not executable by unauthorized users and that the web server runs with minimal necessary privileges. Additional protective measures include implementing proper input sanitization, deploying web application firewalls, and conducting regular security audits to identify and remediate similar vulnerabilities in other web server components. The ATT&CK framework categorizes this vulnerability under privilege escalation and command injection techniques, emphasizing the need for comprehensive security controls that address both the immediate exploit and broader system protection requirements.