CVE-2012-4443 in HTTP Daemon
Summary
by MITRE
Monkey HTTP Daemon 0.9.3 uses a real UID of root and a real GID of root during execution of CGI scripts, which might allow local users to gain privileges by leveraging cgi-bin write access.
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Analysis
by VulDB Data Team • 02/05/2018
The vulnerability identified as CVE-2012-4443 affects the Monkey HTTP Daemon version 0.9.3, a lightweight web server designed for embedded systems and resource-constrained environments. This issue represents a critical privilege escalation flaw that stems from improper privilege management during CGI script execution. The daemon operates with root privileges throughout its runtime, maintaining both real and effective user and group identifiers as root, which creates a significant security exposure when processing CGI content.
The technical flaw manifests when the Monkey HTTP Daemon executes CGI scripts, as it does not properly drop privileges from its root-level execution context. Specifically, the daemon maintains root UID and GID during CGI execution, creating an environment where local users with write access to the cgi-bin directory can manipulate script content to execute arbitrary code with elevated privileges. This behavior directly violates the principle of least privilege and creates a direct pathway for privilege escalation attacks. The vulnerability is particularly dangerous because it leverages the existing write permissions in the cgi-bin directory, making it accessible to any local user who can modify files in that location.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete system control when combined with write access to CGI directories. Local users can craft malicious CGI scripts that execute with root privileges, potentially allowing them to modify system files, install backdoors, or extract sensitive information from the system. This vulnerability is especially concerning in environments where multiple users share the system or where the web server is deployed in a multi-tenant configuration. The attack vector is relatively straightforward, requiring only local access and write permissions to the cgi-bin directory, making it an attractive target for both malicious insiders and external attackers who have gained initial access to the system.
Mitigation strategies for CVE-2012-4443 should focus on privilege separation and access control enforcement. The most effective immediate solution involves modifying the Monkey HTTP Daemon configuration to drop privileges before executing CGI scripts, ensuring that CGI execution occurs with minimal required privileges rather than root privileges. System administrators should implement strict file permissions on cgi-bin directories, limiting write access to authorized users only, and regularly audit these directories for unauthorized modifications. Additionally, the daemon should be updated to a patched version that properly implements privilege dropping mechanisms, as specified in the CWE-276 standard for improper privilege management. Organizations should also consider implementing monitoring solutions that detect unauthorized modifications to CGI directories and establish baseline configurations that prevent unnecessary privilege elevation during script execution, aligning with ATT&CK technique T1068 for local privilege escalation. The vulnerability highlights the importance of proper privilege management in web server implementations and underscores the need for security-conscious development practices that prevent privilege escalation through common execution pathways.