CVE-2015-5501 in Hostmaster Module
Summary
by MITRE
The Hostmaster (Aegir) module 6.x-2.x before 6.x-2.4 and 7.x-3.x before 7.x-3.0-beta2 for Drupal allows remote attackers to execute arbitrary PHP code via a crafted file in the directory used to write Apache vhost files for hosted sites in a multi-site environment.
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Analysis
by VulDB Data Team • 10/18/2017
The CVE-2015-5501 vulnerability affects the Hostmaster module within Drupal, specifically versions 6.x-2.x prior to 6.x-2.4 and 7.x-3.x prior to 7.x-3.0-beta2. This module serves as a critical component in Aegir hosting platforms, which manage multiple Drupal sites from a single installation. The vulnerability stems from improper handling of file operations within the Apache virtual host configuration writing process, creating a dangerous path traversal scenario that enables remote code execution.
The technical flaw manifests when the Hostmaster module writes Apache virtual host files for hosted sites within a multi-site environment. Attackers can exploit this by crafting malicious files with specific naming conventions that bypass normal security checks. The vulnerability occurs because the module does not properly validate or sanitize file names before writing them to directories designated for Apache configuration files. This creates a scenario where attacker-controlled content can be written to locations where Apache will process it as configuration directives, potentially leading to arbitrary code execution.
This vulnerability has significant operational impact within hosting environments where Aegir manages multiple Drupal sites. Remote attackers can leverage this flaw to execute arbitrary PHP code on the hosting server, potentially gaining full control over the affected system. The attack vector is particularly dangerous because it allows execution of code without requiring authentication, making it a critical security risk for organizations relying on Aegir for site management. The vulnerability effectively undermines the security model of multi-site hosting platforms, as attackers can compromise the entire hosting infrastructure through a single vulnerable module.
The exploitability of this vulnerability aligns with CWE-22 Path Traversal and CWE-94 Code Injection, representing a combination of directory traversal and code execution weaknesses. From an ATT&CK perspective, this vulnerability maps to T1190 Exploit Public-Facing Application and T1059 Command and Scripting Interpreter, as it enables attackers to execute commands through the web interface. Organizations should implement immediate mitigations including upgrading to patched versions of the Hostmaster module, implementing proper file name validation, and restricting write permissions to Apache configuration directories. Additionally, network segmentation and monitoring of file write operations in hosting environments can help detect potential exploitation attempts. The vulnerability highlights the importance of secure coding practices in multi-site hosting platforms and demonstrates how seemingly benign file operations can create critical security risks when proper validation is absent.