Source: cve@mitre.org
Directory traversal vulnerability in zml.cgi allows remote attackers to read arbitrary files via a .. (dot dot) in the file parameter.
Remote attackers can exploit a directory traversal vulnerability in zml.cgi to read arbitrary files on a vulnerable server. This allows attackers to potentially access sensitive information, including configuration files, user credentials, and system data, leading to a significant security breach.
Step 1: Payload Delivery: The attacker crafts a malicious URL containing the file parameter with a directory traversal payload, such as file=../../../etc/passwd.
Step 2: Request Submission: The attacker submits the crafted URL to the vulnerable zml.cgi script.
Step 3: Parameter Processing: The zml.cgi script receives the request and extracts the value of the file parameter.
Step 4: Path Construction: The script constructs a file path using the user-supplied file parameter, likely concatenating it with a base directory.
Step 5: File Access: Due to the lack of input validation, the constructed path includes the directory traversal sequence, allowing the script to access files outside the intended web root (e.g., /etc/passwd).
Step 6: Information Disclosure: The contents of the requested file (e.g., /etc/passwd) are returned to the attacker, revealing sensitive information.
The vulnerability stems from insufficient input validation in the zml.cgi script when handling the file parameter. The script fails to properly sanitize the input, allowing attackers to inject ../ sequences into the parameter. This bypasses intended directory restrictions and enables access to files outside the intended web root. The root cause is a lack of proper path normalization and input validation before using the user-supplied file parameter to construct file paths. The script likely directly concatenates the user-provided input with a base directory path without checking for or removing directory traversal sequences. This allows an attacker to craft a malicious file path that navigates up the directory tree.
Due to the age of the vulnerability, it's unlikely to be directly attributed to specific APT groups. However, the ease of exploitation makes it a likely target for opportunistic attacks and botnet compromises. This type of vulnerability is often used by attackers to gain initial access and then escalate privileges. Not listed on CISA KEV due to its age and the likely low number of active deployments.
Network traffic analysis: Look for HTTP requests to zml.cgi with the file parameter containing ../ sequences.
Web server logs: Examine web server access logs for requests to zml.cgi with unusual file paths or directory traversal attempts.
Intrusion Detection System (IDS) signatures: Implement IDS rules to detect directory traversal attempts in HTTP requests.
File integrity monitoring: Monitor critical system files (e.g., /etc/passwd, /etc/shadow) for unauthorized access or modification.
Security Information and Event Management (SIEM) correlation: Correlate web server logs, IDS alerts, and file integrity monitoring events to identify potential exploitation attempts.
Input validation: Implement robust input validation to sanitize the file parameter. This includes removing or encoding ../ sequences and validating the file path against a whitelist of allowed files or directories.
Path normalization: Use a secure path normalization function to resolve relative paths and prevent directory traversal.
Least privilege: Ensure the web server process runs with the least privileges necessary to access files.
Web application firewall (WAF): Deploy a WAF to filter malicious requests and block directory traversal attempts.
Regular security audits: Conduct regular security audits and penetration testing to identify and address vulnerabilities.
Patching: If possible, update the software to a patched version that addresses the vulnerability. If no patch is available, consider removing the vulnerable software.