CVE-2015-9406 in mTheme-Unus Theme
Summary
by MITRE
Directory traversal vulnerability in the mTheme-Unus theme before 2.3 for WordPress allows an attacker to read arbitrary files via a .. (dot dot) in the files parameter to css/css.php.
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Analysis
by VulDB Data Team • 12/27/2023
The CVE-2015-9406 vulnerability represents a critical directory traversal flaw within the mTheme-Unus WordPress theme version 2.2 and earlier. This vulnerability resides in the css/css.php file where the theme fails to properly validate user input, specifically the files parameter that handles CSS file references. The flaw allows attackers to manipulate the file path through the use of directory traversal sequences such as .. (dot dot) which enables unauthorized access to arbitrary files on the server. The vulnerability is particularly dangerous because it operates within a WordPress theme component that is commonly installed and active on numerous websites, making it a prime target for automated exploitation campaigns.
The technical implementation of this vulnerability stems from improper input sanitization and validation within the theme's CSS processing functionality. When the css.php script receives the files parameter, it concatenates user-supplied values directly into file paths without adequate filtering or normalization. This lack of input validation creates a condition where an attacker can inject malicious path sequences that traverse up the directory structure, potentially accessing sensitive files such as wp-config.php, database credentials, or other system configuration files. The vulnerability operates at the application layer and can be exploited through simple HTTP requests that manipulate the files parameter to include directory traversal sequences.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can lead to complete system compromise when combined with other exploitation techniques. Attackers can leverage this vulnerability to obtain administrative credentials, access private user data, or extract database connection details that could facilitate further attacks. The vulnerability affects all WordPress installations using the mTheme-Unus theme version 2.2 or earlier, making it particularly widespread since WordPress themes are frequently updated and deployed across numerous websites. The attack vector is straightforward and requires minimal technical expertise, making it attractive to both automated scanners and targeted attackers.
Mitigation strategies for CVE-2015-9406 primarily focus on immediate theme updates to version 2.3 or later, which contain the necessary input validation fixes. System administrators should also implement web application firewalls that can detect and block directory traversal patterns in URL parameters, particularly those involving .. sequences. Additional protective measures include restricting file permissions on sensitive WordPress files, implementing proper input validation at multiple layers, and conducting regular security audits of installed themes and plugins. This vulnerability aligns with CWE-22 - Improper Limitation of a Pathname to a Restricted Directory and can be mapped to ATT&CK technique T1083 - File and Directory Discovery, as it enables attackers to enumerate and access files that should remain protected. Organizations should also consider implementing automated patch management systems to ensure timely updates of vulnerable components and reduce the window of exposure for such directory traversal vulnerabilities.