Source: cve@mitre.org
BNBSurvey survey.cgi program allows remote attackers to execute commands via shell metacharacters.
BNBSurvey's survey.cgi program is vulnerable to remote command execution, allowing attackers to execute arbitrary commands on the server. This vulnerability, stemming from improper input validation, enables malicious actors to gain complete control of the compromised system, potentially leading to data breaches and service disruption.
Step 1: Input Injection: The attacker crafts a malicious HTTP request to the survey.cgi script, including specially crafted input parameters designed to exploit the vulnerability. These parameters contain shell metacharacters and the desired commands to be executed on the server.
Step 2: Request Processing: The survey.cgi script receives the malicious HTTP request and processes the input parameters. Due to the lack of proper input validation, the script directly incorporates the attacker-controlled input into a shell command.
Step 3: Command Execution: The script executes the crafted shell command, including the attacker's injected commands. The server's operating system interprets and executes these commands with the privileges of the web server user.
Step 4: Command Output (Optional): Depending on the injected command, the attacker may be able to retrieve the output of the executed commands, providing further information about the system and enabling more sophisticated attacks. This could involve redirecting output to a file or a remote server.
The vulnerability lies in the survey.cgi script's failure to properly sanitize user-supplied input before passing it to a shell command. Specifically, the script likely uses the input parameters directly within a system call (e.g., system(), exec(), or similar) without escaping or filtering special characters. This allows an attacker to inject shell metacharacters (e.g., ;, &, |, $(...)) into the input, effectively crafting a malicious command that the server executes. The root cause is a lack of input validation and output encoding, leading to command injection.
Due to the age of the vulnerability, it's unlikely to be directly associated with specific APT groups in recent reports. However, any threat actor seeking to gain initial access or escalate privileges on a web server could leverage this vulnerability. This vulnerability is not listed on the CISA KEV.
Analyze web server logs for suspicious HTTP requests to survey.cgi containing shell metacharacters (e.g., ;, &, |, $(...)).
Monitor file system changes for unexpected modifications, especially in web server directories.
Examine process activity for unusual processes or commands being executed by the web server user.
Network traffic analysis: Look for unusual outbound connections from the web server, which could indicate data exfiltration or command and control activity.
Use a web application firewall (WAF) to detect and block malicious requests containing shell injection attempts.
Patching: The most effective remediation is to apply security patches or updates provided by the vendor. However, given the age of the vulnerability, this may not be possible.
Input Validation: Implement robust input validation to sanitize all user-supplied data. This includes escaping special characters, whitelisting allowed characters, and limiting input length.
Output Encoding: Encode output to prevent cross-site scripting (XSS) vulnerabilities that could arise from the command execution.
Least Privilege: Run the web server with the least privileges necessary to perform its functions. This limits 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.