CVE-2002-1993 in WebBBS
Summary
by MITRE
webbbs_post.pl in WebBBS 4 and 5.0 allows remote attackers to execute arbitrary commands via shell metacharacters in the followup parameter.
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Analysis
by VulDB Data Team • 08/31/2025
The vulnerability identified as CVE-2002-1993 affects WebBBS versions 4 and 5.0, specifically within the webbbs_post.pl script that handles forum posting functionality. This represents a classic command injection flaw that occurs when user input is improperly sanitized before being processed by the application. The vulnerability manifests when attackers manipulate the followup parameter to include shell metacharacters, enabling them to execute arbitrary commands on the underlying operating system. This type of vulnerability falls under the CWE-77 category known as "Improper Neutralization of Special Elements used in a Command ('Command Injection')", which is a fundamental security weakness that has persisted across numerous applications due to inadequate input validation and sanitization practices.
The technical exploitation of this vulnerability occurs through the manipulation of the followup parameter in the webbbs_post.pl script, which is designed to handle reply functionality within the bulletin board system. When the application processes user input without proper sanitization, it directly incorporates the malicious input into system commands, allowing attackers to inject shell commands that get executed with the privileges of the web server process. This creates a critical attack surface where remote adversaries can gain unauthorized access to the underlying system, potentially leading to complete system compromise. The vulnerability is particularly dangerous because it operates at the command execution level, enabling attackers to perform actions such as file manipulation, directory traversal, privilege escalation, and data exfiltration.
The operational impact of CVE-2002-1993 extends beyond simple unauthorized access, as it provides attackers with the capability to establish persistent backdoors, modify or delete system files, and potentially use the compromised server as a launch point for further attacks within the network. The vulnerability can be exploited by any remote user who has access to the bulletin board's posting functionality, making it particularly dangerous in public forum environments where user input is not properly validated. From an attack framework perspective, this vulnerability maps to the ATT&CK technique T1059.001 for Command and Scripting Interpreter, specifically shell commands, and represents a critical entry point that can lead to lateral movement and privilege escalation within compromised environments. The lack of input sanitization in this version of WebBBS demonstrates a fundamental flaw in secure coding practices that was common in legacy web applications of that era.
Mitigation strategies for this vulnerability require immediate implementation of proper input validation and sanitization measures within the webbbs_post.pl script. Organizations should implement strict parameter validation that filters out or escapes shell metacharacters such as semicolons, pipes, and backticks from user input before processing. The recommended approach involves using whitelisting techniques that only allow predefined safe characters and patterns in the followup parameter. Additionally, implementing proper output encoding and using secure coding practices such as those outlined in the OWASP Secure Coding Practices can prevent similar vulnerabilities from occurring in future versions. System administrators should also consider implementing web application firewalls and input validation rules at the network level to provide additional layers of protection. The vulnerability highlights the importance of regular security assessments and code reviews to identify and remediate command injection flaws before they can be exploited by malicious actors.