CVE-2006-4859 in Limbo Cms
Summary
by MITRE
Unrestricted file upload vulnerability in contact.html.php in the Contact (com_contact) component in Limbo (aka Lite Mambo) CMS 1.0.4.2L and earlier allows remote attackers to upload PHP code to the images/contact folder via a filename with a double extension in the contact_attach parameter in a contact option in index.php, which bypasses an insufficiently restrictive regular expression.
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Analysis
by VulDB Data Team • 07/20/2024
The vulnerability described in CVE-2006-4859 represents a critical unrestricted file upload flaw within the Limbo CMS 1.0.4.2L and earlier versions. This vulnerability specifically targets the Contact component's contact.html.php file which handles file attachments through the contact_attach parameter. The flaw enables remote attackers to execute arbitrary PHP code on the target system by uploading malicious files that bypass the application's security controls. The vulnerability stems from an insufficiently restrictive regular expression that fails to properly validate file extensions, allowing attackers to exploit the system through a double extension technique where a filename appears legitimate but contains malicious code.
The technical exploitation of this vulnerability occurs through a carefully crafted filename that includes a double extension such as filename.php.jpg or filename.jpg.php, which the vulnerable application accepts due to the weak validation mechanism. When an attacker submits a file with such a naming convention through the contact_attach parameter in the index.php file, the system processes the upload to the images/contact folder without proper validation of the file type. This allows PHP code to be uploaded and executed within the web server environment, potentially leading to complete system compromise. The vulnerability is categorized under CWE-434 Unrestricted Upload of File with Dangerous Type, which specifically addresses the risk of uploading executable code through web applications.
From an operational standpoint, this vulnerability presents a severe threat to web application security as it allows attackers to gain unauthorized access to the system and potentially escalate privileges. The impact extends beyond simple code execution to include potential data breaches, system compromise, and further lateral movement within the network. Attackers can upload backdoor scripts that provide persistent access to the compromised system, or more sophisticated payloads that can exfiltrate sensitive data or establish command and control channels. This vulnerability also aligns with ATT&CK technique T1190 Exploit Public-Facing Application, as it represents an attack vector that targets publicly accessible web applications. The vulnerability's exploitation requires minimal privileges and can be automated, making it particularly dangerous for organizations running affected versions of the Limbo CMS.
Mitigation strategies for this vulnerability involve immediate patching of the affected Limbo CMS versions to the latest available security updates. Organizations should implement proper file type validation mechanisms that check not only the file extension but also the actual file content and MIME type to ensure that only safe file types are accepted. The application should enforce strict file naming conventions and reject any files with multiple extensions or suspicious naming patterns. Additionally, the upload directory should be configured with appropriate permissions that prevent execution of uploaded files, and the web server should be configured to treat uploaded files as static content rather than executable scripts. Network-based mitigations include implementing web application firewalls that can detect and block malicious file upload attempts, and regular security monitoring to identify suspicious file upload activities. Organizations should also consider implementing principle of least privilege access controls and regularly audit their web applications for similar vulnerabilities that may exist in other components or third-party libraries.