Source: cve@mitre.org
The jj CGI program allows command execution via shell metacharacters.
The jj CGI program is vulnerable to remote command execution, allowing attackers to execute arbitrary commands on the server. This vulnerability, stemming from improper input validation, can lead to complete system compromise and data exfiltration. Successful exploitation grants attackers full control over the affected system.
Step 1: Identify the Target: The attacker identifies a web server running the vulnerable jj CGI program. This may involve port scanning, vulnerability scanning, or public information gathering.
Step 2: Craft the Payload: The attacker crafts a malicious URL containing shell metacharacters within the input parameters of the jj CGI program. This payload includes the command the attacker wants to execute (e.g., whoami, cat /etc/passwd).
Step 3: Send the Request: The attacker sends the crafted URL to the vulnerable web server.
Step 4: Command Execution: The jj CGI program receives the malicious input, but fails to properly sanitize the shell metacharacters. The input is then passed to the operating system's shell for processing.
Step 5: Command Results: The shell executes the injected command. The output of the command (e.g., the user's username, the contents of the password file) may be returned to the attacker, or the attacker may use the command to establish a reverse shell or download a malicious payload.
The vulnerability lies within the jj CGI program's handling of user-supplied input. Specifically, the program fails to properly sanitize or escape shell metacharacters (e.g., ;, |, &, $, `, etc.) within input parameters. This allows an attacker to inject malicious commands into the input, which are then executed by the underlying operating system's shell. The root cause is a lack of input validation and output encoding, allowing for command injection. The flaw is not a buffer overflow or race condition, but rather a logic error in how user-provided data is handled by the CGI program.
Due to the age of the vulnerability, specific APT groups are not directly linked to its exploitation. However, the techniques used are common and could be leveraged by any threat actor. This vulnerability is not present on the CISA KEV list.
Web server access logs: Look for suspicious URLs containing shell metacharacters (e.g., ;, |, &, $).
Network traffic analysis: Examine HTTP requests for unusual parameters or command injection attempts.
File system monitoring: Monitor for the creation of new files or modification of existing files, especially in web server directories.
Intrusion Detection System (IDS) and Intrusion Prevention System (IPS) rules: Implement rules to detect and block known command injection patterns.
Web Application Firewall (WAF) logs: Review WAF logs for blocked requests containing malicious payloads.
Input Validation: Implement strict input validation to sanitize and filter all user-supplied data. This includes escaping shell metacharacters and validating the format and content of input parameters.
Output Encoding: Encode output data to prevent cross-site scripting (XSS) and other vulnerabilities.
Least Privilege: Run the jj CGI program with the least privileges necessary to perform its function.
Web Server Hardening: Harden the web server by disabling unnecessary features and services.
Patching: If possible, update the jj CGI program to a patched version that addresses the vulnerability. If no patch is available, consider removing the program or replacing it with a more secure alternative.
Regular Security Audits: Conduct regular security audits and penetration testing to identify and address vulnerabilities.