CVE-2002-0489 in Nslookup
Summary
by MITRE
Linux Directory Penguin NsLookup CGI script (nslookup.pl) 1.0 allows remote attackers to execute arbitrary code via shell metacharacters in the (1) query or (2) type parameters.
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Analysis
by VulDB Data Team • 09/16/2025
The vulnerability identified as CVE-2002-0489 affects the Linux Directory Penguin NsLookup CGI script version 1.0, representing a critical security flaw that enables remote code execution through improper input validation. This issue stems from the script's failure to sanitize user-provided parameters before incorporating them into shell commands, creating an environment where malicious actors can inject shell metacharacters to execute arbitrary commands on the affected system. The vulnerability specifically impacts the query and type parameters of the nslookup.pl script, which are processed without adequate sanitization measures.
The technical implementation of this vulnerability resides in the script's handling of user input through CGI parameters, where the application directly concatenates user-supplied data into shell command invocations without proper filtering or escaping mechanisms. This design flaw aligns with CWE-77, known as Improper Neutralization of Special Elements used in a Command, which is a fundamental weakness in command injection vulnerabilities. The vulnerability allows attackers to manipulate the script's behavior by inserting shell metacharacters such as semicolons, ampersands, or backticks that alter the intended execution flow of the underlying shell commands.
Operationally, this vulnerability presents a severe risk to systems running the affected NsLookup CGI script, as it provides remote attackers with complete control over the affected system's command execution capabilities. Attackers can leverage this flaw to execute any command that the web server process has permissions to run, potentially leading to full system compromise, data exfiltration, or further lateral movement within the network infrastructure. The impact extends beyond simple command execution, as the vulnerability can be exploited to establish persistent backdoors, modify system files, or access sensitive data stored on the server.
The exploitation of this vulnerability requires minimal technical expertise and can be accomplished through standard web-based attack vectors, making it particularly dangerous in environments where the script is accessible over the internet. Organizations should immediately implement mitigations including input validation, parameter sanitization, and the removal or patching of the vulnerable script. Additionally, implementing web application firewalls and restricting access to CGI scripts can help reduce the attack surface. This vulnerability demonstrates the critical importance of proper input validation and output encoding in web applications, as outlined in the ATT&CK framework's command and control techniques, specifically targeting the execution of arbitrary code through web-based interfaces.