Source: cve@mitre.org
go.cgi in GoScript 2.0 allows remote attackers to execute arbitrary commands via shell metacharacters in the (1) query string or (2) artarchive parameter.
GoScript 2.0 suffers from a critical vulnerability allowing remote attackers to execute arbitrary commands on the server. This is achieved through improper handling of user-supplied input within the go.cgi script, enabling command injection via the query string or artarchive parameter, leading to complete system compromise. Successful exploitation grants attackers full control over the affected system, potentially leading to data breaches, system outages, and further malicious activities.
Step 1: Payload Delivery: The attacker crafts a malicious URL containing shell metacharacters in either the query string or the artarchive parameter. For example, http://target.com/go.cgi?param=value;whoami or http://target.com/go.cgi?artarchive=;cat /etc/passwd.
Step 2: Input Processing: The go.cgi script receives the malicious request and extracts the user-supplied input from the query string or artarchive parameter.
Step 3: Command Construction: The script, due to the lack of proper input validation, directly incorporates the attacker-controlled input into a shell command.
Step 4: Command Execution: The shell interprets the injected metacharacters as commands and executes them on the server. The attacker's commands are executed with the privileges of the user running the web server (e.g., www-data, apache).
Step 5: Result Retrieval (Optional): The attacker may be able to retrieve the output of their commands, depending on the script's behavior and the commands used. This could involve writing to a file, sending data over the network, or other methods.
The root cause lies in the go.cgi script's failure to properly sanitize user-supplied input before passing it to the underlying shell. Specifically, the script directly incorporates data from the query string or the artarchive parameter into shell commands without escaping or filtering special characters. This allows an attacker to inject shell metacharacters (e.g., ;, &, |, $(...)) into the input, effectively executing arbitrary commands on the server. The lack of input validation and output encoding creates a direct path for command injection, leading to remote code execution (RCE). The vulnerability is exacerbated by the script's likely execution with elevated privileges, potentially granting attackers significant control over the system.
Due to the age of the vulnerability, it's likely that various threat actors, including both sophisticated APTs and opportunistic script kiddies, could exploit it. There is no specific APT attribution available. This vulnerability is not listed on the CISA KEV at this time, but given its potential impact, it could be a target for future inclusion if it is found to be actively exploited.
Monitor web server logs (e.g., Apache access logs, Nginx access logs) for suspicious HTTP requests containing shell metacharacters in the query string or artarchive parameter. Examples include ;, &, |, $(...), backticks, and other shell special characters.
Implement a Web Application Firewall (WAF) with rules specifically designed to detect and block command injection attempts. This should include regular expression-based filtering for malicious patterns.
Analyze network traffic for unusual outbound connections originating from the web server, which could indicate command execution and data exfiltration.
Check for the presence of unexpected files or modifications to existing files on the web server, which could be a sign of compromise.
Use intrusion detection systems (IDS) and intrusion prevention systems (IPS) with signatures specifically designed to detect command injection attempts against web applications.
Upgrade: The most effective remediation is to upgrade to a version of GoScript that addresses this vulnerability. Since GoScript 2.0 is likely outdated, this may involve migrating to a different web application or content management system.
Input Validation: Implement robust input validation to sanitize all user-supplied input before using it in any shell commands. This should include escaping special characters and restricting the allowed input characters.
Least Privilege: Run the web server process with the least privileges necessary. This will limit the impact of a successful exploit.
Web Application Firewall (WAF): Deploy a WAF to detect and block malicious requests attempting to exploit this vulnerability.
Regular Security Audits: Conduct regular security audits and penetration testing to identify and address vulnerabilities in the web application.
Disable Unused Features: Disable or remove the go.cgi script if it is not actively used.