Source: cve@mitre.org
nlog CGI scripts do not properly filter shell metacharacters from the IP address argument, which could allow remote attackers to execute certain commands via (1) nlog-smb.pl or (2) rpc-nlog.pl.
Remote attackers can execute arbitrary commands on vulnerable servers by exploiting a command injection vulnerability in the nlog CGI scripts. This allows attackers to gain unauthorized access and potentially compromise the entire system, leading to data breaches and system outages.
Step 1: Payload Delivery: The attacker crafts a malicious HTTP request targeting either nlog-smb.pl or rpc-nlog.pl CGI scripts.
Step 2: Malicious Input: The attacker includes a crafted IP address containing shell metacharacters (e.g., 127.0.0.1; whoami).
Step 3: Script Execution: The vulnerable CGI script receives the malicious IP address.
Step 4: Command Injection: The script, without proper sanitization, passes the attacker-controlled IP address to a shell command (likely using system(), exec(), or similar functions).
Step 5: Command Execution: The shell interprets the metacharacters and executes the attacker-specified commands (e.g., whoami).
Step 6: Result Retrieval: The attacker may receive the output of the executed command (e.g., the username of the process running the web server) or use the command to perform further actions.
The vulnerability stems from insufficient input validation in the nlog CGI scripts (nlog-smb.pl and rpc-nlog.pl). These scripts fail to properly sanitize the IP address argument passed to them. This allows attackers to inject shell metacharacters (e.g., ;, |, &, $) within the IP address field. These metacharacters are then interpreted by the underlying shell, leading to the execution of attacker-controlled commands. The root cause is the lack of proper input sanitization and output encoding, allowing for command injection.
Due to the age of the vulnerability, it's unlikely to be directly associated with specific APT groups in recent reports. However, the ease of exploitation makes it a prime target for opportunistic attackers and botnets. This vulnerability is not listed in CISA KEV as it is an older vulnerability.
Analyze web server logs (e.g., Apache access logs, Nginx access logs) for suspicious HTTP requests targeting nlog-smb.pl or rpc-nlog.pl with unusual IP address formats or shell metacharacters in the IP address field.
Monitor network traffic for unusual outbound connections from the web server, especially to suspicious IP addresses or ports.
Implement a Web Application Firewall (WAF) to detect and block malicious requests containing shell metacharacters in the IP address or other request parameters.
Use intrusion detection systems (IDS) with signatures specifically designed to detect command injection attempts.
Review system logs for evidence of command execution, such as unusual processes or file modifications.
Patching: The primary remediation is to apply the security patches for the affected systems. Since this is an old vulnerability, patching may not be directly available. Consider upgrading to a newer, secure version of the software or operating system.
Input Validation: Implement robust input validation to sanitize all user-supplied data, including the IP address argument. This should involve filtering out or escaping shell metacharacters.
Least Privilege: Run the web server and CGI scripts with the least privileges necessary to perform their functions. This limits the potential damage if a command injection attack is successful.
Web Application Firewall (WAF): Deploy a WAF to filter malicious requests and prevent command injection attempts.
Regular Security Audits: Conduct regular security audits and penetration testing to identify and address vulnerabilities.
Disable Unused Services: Disable or remove the vulnerable CGI scripts if they are not essential for the system's functionality.