CVE-2001-0437 in DCForum
Summary
by MITRE
upload_file.pl in DCForum 2000 1.0 allows remote attackers to upload arbitrary files without authentication by setting the az parameter to upload_file.
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Analysis
by VulDB Data Team • 06/25/2021
The vulnerability identified as CVE-2001-0437 resides within DCForum 2000 1.0's upload_file.pl script which presents a critical security flaw allowing unauthenticated remote code execution through arbitrary file uploads. This issue stems from inadequate input validation and authentication mechanisms within the web application's file upload functionality. The vulnerability specifically manifests when attackers manipulate the az parameter to directly invoke the upload_file function without proper authorization checks, effectively bypassing the application's security controls.
The technical implementation of this vulnerability demonstrates a classic lack of proper access control enforcement within the application's parameter handling. The upload_file.pl script fails to validate whether the requesting user possesses appropriate permissions before processing file upload requests, creating an exploitable path for malicious actors to bypass authentication requirements entirely. This flaw operates at the application logic level and represents a fundamental failure in the principle of least privilege, where the system grants elevated capabilities to unauthenticated users through parameter manipulation.
From an operational impact perspective, this vulnerability creates significant risk for organizations utilizing DCForum 2000 1.0 as it enables remote attackers to upload malicious files to the server, potentially including web shells, backdoors, or other malicious payloads. The absence of authentication requirements means that any remote user can exploit this vulnerability without requiring valid credentials, transforming what should be a controlled administrative function into an open attack surface. This vulnerability aligns with CWE-285 which addresses improper authorization issues, and specifically relates to the broader category of insecure direct object references that allow attackers to bypass access control mechanisms.
The exploitation of this vulnerability can lead to complete system compromise, as attackers can upload executable files that may be executed by the web server, potentially enabling them to gain remote command execution capabilities. This represents a severe escalation from a simple file upload vulnerability to a full system compromise scenario, particularly when combined with other vulnerabilities or when the web server has elevated privileges. The attack vector operates entirely through HTTP requests, making it easily exploitable from any location without requiring physical access to the system.
Organizations should implement immediate mitigations including disabling or removing the vulnerable upload functionality, implementing proper authentication checks before allowing file uploads, and conducting thorough input validation on all user-supplied parameters. Network-level protections such as web application firewalls can help detect and block exploitation attempts, while regular security audits should verify that all file upload mechanisms properly enforce access controls. The vulnerability demonstrates the critical importance of implementing proper authorization checks for all application functions, particularly those involving file operations, as outlined in the ATT&CK framework's technique T1059 for command and scripting interpreter and T1505 for server-side injection techniques. Organizations should also consider implementing file type validation, upload size restrictions, and proper file naming conventions to prevent exploitation of similar vulnerabilities in the future.