CVE-2002-1843 in Perlbot
Summary
by MITRE
Perlbot 1.9.2 allows remote attackers to execute arbitrary commands via shell metacharacters in (1) the $text variable in SpelCheck.pm or (2) the $filename variable in HTMLPlog.pm.
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Analysis
by VulDB Data Team • 07/04/2024
The vulnerability identified as CVE-2002-1843 affects Perlbot 1.9.2, a web-based chat bot application that processes user input through various Perl modules. This flaw represents a classic command injection vulnerability that arises from insufficient input sanitization within the application's processing pipeline. The vulnerability exists in two distinct locations within the Perlbot codebase, specifically in the SpelCheck.pm module where the $text variable is processed and in the HTMLPlog.pm module where the $filename variable is handled. Both locations fail to properly validate or escape user-supplied input before incorporating it into system commands or file operations, creating opportunities for malicious actors to inject shell metacharacters that can be interpreted by the underlying operating system.
The technical implementation of this vulnerability stems from the application's reliance on user-provided data without adequate sanitization measures. When users interact with the chat bot, their input is directly processed through these vulnerable modules without proper input validation or escaping mechanisms. The $text variable in SpelCheck.pm likely handles spelling correction functionality where user text input is passed to shell commands for spell checking operations. Similarly, the $filename variable in HTMLPlog.pm processes file naming operations that may involve shell commands for log file management. Both scenarios create opportunities for attackers to inject shell metacharacters such as semicolons, pipes, or backticks that can trigger arbitrary command execution on the server hosting the Perlbot application. This vulnerability directly maps to CWE-77 which describes improper neutralization of special elements used in commands, and CWE-94 which addresses improper execution of code.
The operational impact of CVE-2002-1843 is severe and potentially catastrophic for affected systems. Remote attackers can execute arbitrary commands with the privileges of the web server process, which typically runs with elevated permissions to access system resources, files, and potentially other services running on the same host. This allows for complete system compromise including data exfiltration, privilege escalation, installation of backdoors, and further network reconnaissance. The vulnerability's remote nature means that attackers do not require local system access or credentials to exploit it, making it particularly dangerous in publicly accessible web environments. Attackers could leverage this vulnerability to establish persistent access, deploy malware, or use the compromised system as a launch point for attacks on other networked systems. The impact extends beyond immediate system compromise to include potential data breaches, service disruption, and compliance violations that could result in significant financial and reputational damage.
Mitigation strategies for this vulnerability must address the fundamental input handling issues within the Perlbot application. The most effective immediate solution involves implementing proper input sanitization and escaping mechanisms in both vulnerable modules, specifically ensuring that all user-supplied data is properly validated and escaped before being used in shell commands or file operations. This includes implementing proper parameter validation, using safe system call interfaces, and avoiding direct shell command execution with user input. Organizations should also consider applying the vendor-supplied patch or upgrade to a newer version of Perlbot that addresses this vulnerability. Additional security measures include implementing network segmentation to limit access to the vulnerable application, deploying web application firewalls to detect and block malicious input patterns, and conducting regular security audits of web applications to identify similar input validation flaws. The remediation process should align with ATT&CK technique T1059.001 for command and script injection, emphasizing the importance of input validation as a primary defense mechanism against such attacks. System administrators should also implement monitoring and logging to detect suspicious command execution patterns that may indicate exploitation attempts.