CVE-2018-7603 in Search Autocomplete
Summary
by MITRE
In Drupal's 3rd party module search auto complete prior to versions 7.x-4.8 there is a Cross Site Scripting vulnerability. This Search Autocomplete module enables you to autocomplete textfield using data from your website (nodes, comments, etc.). The module doesn't sufficiently filter user-entered text among the autocompletion items leading to a Cross Site Scripting (XSS) vulnerability. This vulnerability can be exploited by any user allowed to create one of the autocompletion item, for instance, nodes, users, comments.
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Analysis
by VulDB Data Team • 07/01/2023
The vulnerability identified as CVE-2018-7603 affects the Drupal Search Autocomplete module, specifically versions prior to 7.x-4.8, representing a critical cross site scripting flaw that compromises web application security. This vulnerability resides within a third-party module that extends Drupal's core functionality by enabling autocomplete features for text fields using data from website content including nodes, comments, and user information. The module's design allows administrators to create autocompletion items that populate text fields dynamically, providing a convenient user experience but inadvertently introducing security risks. The flaw stems from insufficient input sanitization and output encoding mechanisms within the module's processing pipeline.
The technical implementation of this vulnerability occurs when user-provided content is incorporated into autocompletion results without proper sanitization of potentially malicious input. Attackers can exploit this weakness by creating autocompletion items containing malicious javascript code or other harmful payloads within the text fields that are processed by the module. When other users interact with these autocomplete features, the malicious content executes within their browser context, potentially leading to session hijacking, data theft, or further compromise of the affected Drupal installation. This vulnerability is classified under CWE-79 as a cross site scripting flaw, specifically representing a stored XSS variant where malicious code persists in the application's database and executes upon subsequent requests.
The operational impact of this vulnerability extends beyond simple script execution, as it can be leveraged for more sophisticated attacks within the Drupal environment. An attacker with permissions to create autocompletion items can effectively compromise any user who interacts with the affected autocomplete fields, making this particularly dangerous in multi-user environments where various privilege levels exist. The vulnerability affects not only content creators but also regular website visitors who encounter the malicious autocomplete suggestions, creating a broad attack surface. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1059.007 for script injection and T1531 for credential access, as it can be used to harvest user sessions and potentially escalate privileges within the Drupal system. The attack vector is particularly concerning because it requires minimal privileges to exploit, as the attacker only needs permissions to create autocompletion items rather than administrative access.
Mitigation strategies for CVE-2018-7603 primarily focus on immediate patching of the affected module to version 7.x-4.8 or later, which includes proper input sanitization and output encoding measures. Organizations should conduct thorough security assessments of their Drupal installations to identify all instances of the vulnerable module and ensure proper patch management procedures are in place. Additional defensive measures include implementing content security policies to limit script execution, configuring proper input validation for all user-entered content, and establishing monitoring procedures to detect suspicious autocompletion item creation. Security teams should also consider implementing web application firewalls to detect and block potential exploitation attempts, while maintaining regular security audits to ensure the continued integrity of the Drupal environment and its third-party modules.