CVE-2008-3219 in Drupal
Summary
by MITRE
The Drupal filter_xss_admin function in 5.x before 5.8 and 6.x before 6.3 does not "prevent use of the object HTML tag in administrator input," which has unknown impact and attack vectors, probably related to an insufficient cross-site scripting (XSS) protection mechanism.
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Analysis
by VulDB Data Team • 09/29/2018
The vulnerability identified as CVE-2008-3219 represents a critical security flaw in the Drupal content management system affecting versions 5.x prior to 5.8 and 6.x prior to 6.3. This issue specifically targets the filter_xss_admin function which is designed to sanitize user input and prevent cross-site scripting attacks. The vulnerability arises from an insufficient implementation of HTML tag filtering mechanisms, particularly failing to properly restrict the use of the object HTML tag in administrator input contexts. The object tag in HTML is particularly dangerous as it can be used to embed active content such as java applets, flash objects, or other executable elements that can bypass standard XSS protection measures. This oversight creates a potential attack vector where malicious administrators or attackers who can manipulate administrator input might exploit this weakness to execute arbitrary code or inject malicious content into the Drupal system.
The technical flaw stems from the inadequate validation and sanitization of HTML input within the Drupal administration interface. When administrators input content that includes the object tag, the filter_xss_admin function fails to properly strip or escape this dangerous HTML element, allowing it to pass through the security filtering mechanisms. This represents a classic case of insufficient input validation and output encoding, which falls under CWE-79 - Improper Neutralization of Input During Web Page Generation. The vulnerability is particularly concerning because it specifically targets administrator input, meaning that if an attacker can gain administrative privileges or manipulate administrator workflows, they could leverage this weakness to execute malicious code within the context of the web application. The object tag's ability to embed external resources and execute code makes it a prime target for attackers seeking to establish persistent access or perform more sophisticated attacks.
The operational impact of this vulnerability extends beyond simple XSS attacks and could potentially enable more severe security breaches within Drupal installations. Attackers who can exploit this weakness might be able to inject malicious objects that can execute scripts in the browser context of administrators or end users, leading to session hijacking, credential theft, or complete system compromise. The unknown impact and attack vectors mentioned in the original description suggest that the full scope of potential exploitation methods was not fully understood at the time of disclosure, which is typical for vulnerabilities that allow the use of dangerous HTML tags. This vulnerability affects the core security model of Drupal's content filtering system, potentially undermining the trust model that administrators rely on when managing content and user inputs. The attack surface is particularly broad since the vulnerability affects both Drupal 5.x and 6.x versions, representing a significant portion of the Drupal user base at that time.
Mitigation strategies for this vulnerability should focus on immediate patching of affected Drupal installations to versions 5.8 and 6.3 or later, which contain the necessary fixes for the filter_xss_admin function. Organizations should implement additional security layers including web application firewalls that can detect and block suspicious object tag usage, and conduct thorough input validation on all administrator inputs. The fix implemented in the patched versions likely involved strengthening the HTML tag filtering mechanism to properly reject or escape object tags, aligning with the principles of secure input validation and output encoding. Security teams should also consider implementing monitoring for unusual administrative activities and establishing more robust access controls to limit the potential impact of compromised administrator accounts. This vulnerability highlights the importance of comprehensive HTML sanitization in web applications and aligns with ATT&CK techniques related to command and control through web application exploitation, particularly the use of malicious HTML content to establish persistent access. Organizations should also review their overall security posture and ensure that their input validation mechanisms are robust enough to handle all potentially dangerous HTML elements, not just the most commonly exploited ones.