CVE-2015-5513 in Shibboleth Authentication Module
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the Shibboleth authentication module 6.x-4.x before 6.x-4.2 and 7.x-4.x before 7.x-4.2 for Drupal allows remote authenticated users with the "Administer blocks" permission to inject arbitrary web script or HTML via unspecified vectors related to a login link.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 10/18/2017
The CVE-2015-5513 vulnerability represents a critical cross-site scripting flaw within the Shibboleth authentication module for Drupal platforms, affecting versions 6.x-4.x prior to 6.x-4.2 and 7.x-4.x prior to 7.x-4.2. This vulnerability specifically targets the authentication module's handling of login links and exposes systems to potential exploitation by authenticated users who possess the "Administer blocks" permission. The flaw falls under the category of CWE-79 Improper Neutralization of Input During Web Page Generation, which is a fundamental weakness in web application security that allows malicious code injection into web pages viewed by other users. The vulnerability's presence in the Shibboleth module creates a particularly dangerous scenario since this module typically handles sensitive authentication processes and user session management.
The technical exploitation of this vulnerability occurs through unspecified vectors related to login link handling within the Shibboleth authentication module. Attackers with the "Administer blocks" permission can manipulate the module's processing of login links to inject malicious scripts or HTML content that will execute in the context of other users' browsers. This permission level is significant because it allows users to modify block content, which often includes navigation elements, login forms, and other interactive components that are rendered on web pages. The vulnerability essentially creates a code execution channel where malicious payloads can be stored in block configurations and subsequently delivered to unsuspecting users when they access pages containing these compromised blocks. The attack vector leverages the trust relationship between the Drupal system and its authenticated users, making it particularly challenging to detect and prevent.
The operational impact of CVE-2015-5513 extends far beyond simple script injection, as it enables attackers to perform a wide range of malicious activities through the compromised authentication module. Successful exploitation can lead to session hijacking, where attackers steal user credentials and session tokens to impersonate legitimate users. Additionally, the vulnerability can facilitate data theft, including sensitive information from user accounts, administrative data, and potentially system-level information. The attack can also be used to redirect users to malicious websites, install malware on user systems, or perform actions on behalf of users without their knowledge. Given that Shibboleth authentication modules are commonly used in enterprise and institutional environments where sensitive data is handled, the potential for significant damage increases substantially. The vulnerability's ability to persist through block configurations means that malicious code can remain active for extended periods until the compromised blocks are discovered and cleaned.
Mitigation strategies for CVE-2015-5513 should focus on immediate patching of affected Drupal installations, with administrators upgrading to the patched versions 6.x-4.2 and 7.x-4.2. In environments where immediate patching is not feasible, administrators should implement strict access controls to limit the number of users with "Administer blocks" permissions, as this reduces the attack surface significantly. Input validation and sanitization measures should be enhanced to filter and escape any user-supplied content before it is rendered in web pages. The implementation of Content Security Policy (CSP) headers can provide an additional layer of protection by restricting the sources from which scripts can be loaded. Security monitoring should include regular audits of block configurations and user permissions to detect unauthorized modifications. Organizations should also consider implementing web application firewalls that can detect and block known XSS attack patterns, and conduct regular security assessments to identify similar vulnerabilities in other modules and components. The vulnerability's classification under the ATT&CK framework would fall under T1059 Command and Scripting Interpreter and T1548 Abuse of Functionality, highlighting the need for comprehensive defensive measures that address both the immediate exploitation vectors and broader security posture improvements.