Source: cve@mitre.org
Remote attacker can execute commands through Majordomo using the Reply-To field and a "lists" command.
Majordomo, a popular mailing list manager, is vulnerable to remote command execution. An attacker can leverage the Reply-To field and the lists command to inject and execute arbitrary commands on the server, potentially leading to complete system compromise.
Step 1: Craft Malicious Email: The attacker crafts an email message. The email's Reply-To header contains a malicious command, typically using shell metacharacters (e.g., ;, |, &) to execute arbitrary commands.
Step 2: Send to Majordomo: The attacker sends the crafted email to the Majordomo server's address (e.g., majordomo@example.com).
Step 3: Trigger 'lists' Command: The attacker may need to trigger the lists command. This can sometimes be achieved by simply sending the email. Other times, the attacker may need to send a separate email to Majordomo with a command like lists in the body.
Step 4: Command Execution: Majordomo processes the email and, due to the vulnerability, executes the commands injected in the Reply-To field. This can lead to the execution of arbitrary commands with the privileges of the Majordomo process (often a user with significant permissions).
The vulnerability stems from insufficient input validation within Majordomo's processing of the Reply-To header when handling the lists command. Specifically, the software fails to properly sanitize the Reply-To field, allowing an attacker to inject shell commands. When Majordomo processes the lists command, it may use the Reply-To field in a way that allows the injected commands to be executed by the underlying operating system. The root cause is a lack of proper input validation and output encoding, leading to a command injection vulnerability.
This vulnerability is not directly associated with specific APT groups or malware campaigns in modern times due to its age. However, if a vulnerable system is discovered, any attacker could leverage it. CISA KEV: Not Listed
Monitor email logs for suspicious Reply-To headers containing shell metacharacters (e.g., ;, |, &, $(, `).
Analyze Majordomo's log files for unusual activity, especially related to the processing of the lists command.
Network traffic analysis: Look for unusual network connections originating from the Majordomo server after receiving emails with suspicious Reply-To headers.
File integrity monitoring: Monitor critical system files for unauthorized modifications.
Upgrade to a patched version of Majordomo or a more secure mailing list manager. If upgrading is not possible, consider disabling the lists command if not required.
Implement robust input validation and output encoding to sanitize all user-supplied data, especially the Reply-To header.
Restrict the permissions of the Majordomo process to the minimum necessary.
Apply the principle of least privilege to all user accounts on the server.
Implement a Web Application Firewall (WAF) to filter malicious requests.