CVE-2008-3741 in Drupal
Summary
by MITRE
The private filesystem in Drupal 5.x before 5.10 and 6.x before 6.4 trusts the MIME type sent by a web browser, which allows remote authenticated users to conduct cross-site scripting (XSS) attacks by uploading files containing arbitrary web script or HTML.
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Analysis
by VulDB Data Team • 08/16/2019
The vulnerability described in CVE-2008-3741 represents a critical security flaw in the Drupal content management system that specifically affects versions 5.x prior to 5.10 and 6.x prior to 6.4. This issue resides within the private filesystem implementation where the system fails to properly validate file upload operations by relying solely on the MIME type information provided by the web browser. The trust placed in browser-sent MIME type headers creates a dangerous attack vector that can be exploited by authenticated users with appropriate privileges to upload malicious files containing cross-site scripting payloads. The vulnerability stems from the fundamental assumption that browser-provided metadata can be trusted without additional validation, which directly contravenes security best practices for file upload validation mechanisms.
The technical exploitation of this vulnerability occurs when an authenticated user leverages their privileges to upload files that contain malicious script code or HTML content. The system accepts these uploads without proper verification of the actual file content, instead trusting the MIME type header that the browser sends during the file upload process. This allows attackers to bypass normal security checks that would typically validate file extensions, content types, and actual file signatures. When the malicious files are subsequently accessed or processed by the web application, the embedded scripts execute in the context of other users' browsers, enabling the execution of arbitrary code and potential data theft or session hijacking. The vulnerability specifically enables cross-site scripting attacks because the system does not properly sanitize or validate the content of uploaded files against their claimed MIME types, creating a scenario where the server treats malicious content as legitimate.
The operational impact of this vulnerability extends beyond simple XSS attacks, as it can be leveraged to compromise entire web applications and user sessions within the Drupal environment. Attackers can upload files that contain malicious JavaScript code, which executes when users view the uploaded content or when the system processes the files. This can lead to session hijacking, data exfiltration, and further exploitation of the compromised Drupal installation. The vulnerability affects authenticated users, meaning that an attacker must first obtain valid credentials, but once inside the system, they can escalate their privileges through file upload attacks. The impact is particularly severe because it allows attackers to persist within the application and potentially use the uploaded files as a foothold for further attacks against the underlying infrastructure or other systems connected to the Drupal installation.
Organizations should implement multiple layers of defense to mitigate this vulnerability, beginning with immediate patching of affected Drupal versions to the recommended secure releases. The fix typically involves implementing proper file validation mechanisms that verify the actual content of uploaded files rather than relying solely on browser-provided MIME type headers. This includes implementing content-type checking, file extension validation, and actual file signature verification to ensure that uploaded files match their claimed types. Security controls should also include implementing strict file upload policies that restrict the types of files that can be uploaded and stored within the system, along with proper access controls and monitoring of file upload activities. From a compliance perspective, this vulnerability aligns with CWE-1004 which addresses insecure default configurations and CWE-20 which covers insecure input validation practices. The attack pattern described corresponds to ATT&CK technique T1566 which involves phishing with malicious attachments, and T1059 which covers command and scripting interpreters, as attackers can use uploaded files to execute malicious commands within the target environment. Organizations should also consider implementing web application firewalls and content security policies to provide additional protection against exploitation of such vulnerabilities.