CVE-2005-4094 in DoceboLMS
Summary
by MITRE
connector.php in the fckeditor2rc2 addon in DoceboLMS 2.0.4 allows remote attackers to execute arbitrary PHP by using the FileUpload command to upload a file that appears to be an image but contains PHP script.
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Analysis
by VulDB Data Team • 07/14/2018
The vulnerability described in CVE-2005-4094 represents a critical file upload security flaw within the DoceboLMS 2.0.4 learning management system that specifically affects the fckeditor2rc2 addon component. This vulnerability resides in the connector.php file which handles file upload operations through the FileUpload command functionality. The flaw stems from inadequate input validation and file type verification mechanisms that fail to properly distinguish between legitimate image files and maliciously crafted files containing embedded PHP code. Attackers can exploit this weakness by crafting files that appear to be innocent image formats such as jpg or png but contain malicious PHP script within their content, thereby bypassing the intended security restrictions.
The technical implementation of this vulnerability follows a classic file upload attack pattern where the attacker leverages the FileUpload command to submit a file to the server without proper validation of the file's actual content. The vulnerability is categorized under CWE-434 which specifically addresses "Unrestricted Upload of File with Dangerous Type" and aligns with ATT&CK technique T1190 "Exploit Public-Facing Application" as it targets a publicly accessible web application component. The flaw essentially allows an attacker to upload a file that appears to be an image based on its extension but contains executable PHP code that gets processed by the web server, creating a persistent backdoor or execution environment on the target system.
The operational impact of this vulnerability is severe as it provides remote attackers with arbitrary code execution capabilities on the affected DoceboLMS server. Once successfully exploited, attackers can execute malicious PHP code with the privileges of the web server process, potentially leading to complete system compromise, data exfiltration, or further lateral movement within the network infrastructure. The vulnerability affects the confidentiality, integrity, and availability of the system as attackers can modify files, delete content, or establish persistent access points. This type of vulnerability is particularly dangerous in educational environments where DoceboLMS systems may contain sensitive student information, course materials, and institutional data that could be compromised through such an attack vector.
Mitigation strategies for this vulnerability should include implementing strict file type validation that examines both the file extension and the actual file content using MIME type detection and file signature verification. The system should enforce a whitelist approach for allowed file types rather than relying on blacklist validation which can be easily bypassed. Additionally, uploaded files should be stored in a separate directory from the web root with restricted permissions and should not be directly executable. The fckeditor2rc2 addon should be updated to a version that implements proper file validation and sanitization mechanisms. Network segmentation and web application firewalls can provide additional layers of protection by monitoring and blocking suspicious file upload activities. Organizations should also implement regular security audits and penetration testing to identify similar vulnerabilities in their web applications and ensure that file upload functionalities properly validate file content rather than just relying on extension-based checks.