CVE-2015-9456 in orbisius-child-theme-creator Plugin
Summary
by MITRE
The orbisius-child-theme-creator plugin before 1.2.8 for WordPress has incorrect access control for file modification via the wp-admin/admin-ajax.php?action=orbisius_ctc_theme_editor_ajax&sub_cmd=save_file theme_1, theme_1_file, or theme_1_file_contents parameter.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/27/2020
The vulnerability identified as CVE-2015-9456 affects the orbisius-child-theme-creator WordPress plugin version 1.2.7 and earlier, representing a critical access control flaw that allows unauthorized modification of theme files through the WordPress administrative interface. This issue specifically targets the wp-admin/admin-ajax.php endpoint which serves as a central AJAX handler for WordPress plugins and themes, making it a prime target for exploitation by attackers seeking to manipulate core website components. The vulnerability resides in the plugin's handling of the orbisius_ctc_theme_editor_ajax action, which processes theme file modifications through the sub_cmd parameter with save_file command, creating a direct pathway for privilege escalation attacks.
The technical flaw manifests through improper validation of user permissions when processing file modification requests through the admin-ajax.php endpoint. Attackers can exploit this by crafting malicious requests that include the theme_1, theme_1_file, or theme_1_file_contents parameters, bypassing the standard WordPress permission checks that should normally prevent unauthorized access to theme editing functionality. This vulnerability falls under CWE-284, which specifically addresses inadequate access control mechanisms, and represents a classic example of insufficient authorization checks that allow authenticated but unprivileged users to perform administrative actions. The flaw essentially eliminates the distinction between regular user accounts and administrator privileges when it comes to modifying theme files, creating a pathway for attackers to inject malicious code or alter website functionality.
The operational impact of this vulnerability extends beyond simple unauthorized file modification, as it provides attackers with the capability to completely compromise website integrity and potentially establish persistent backdoors within the WordPress environment. Once exploited, attackers can modify core theme files to include malicious code that could redirect visitors to phishing sites, steal cookies and session data, or serve malware downloads to users. The vulnerability also aligns with ATT&CK technique T1546.004, which covers "Event Triggered Execution: Registry Run Keys / Startup Folder," as attackers could modify theme files to include malicious code that executes during normal website operations. This creates a persistent threat vector that remains active as long as the compromised theme files exist, making it particularly dangerous for websites that rely on custom themes and child themes for their functionality.
Mitigation strategies for CVE-2015-9456 should include immediate plugin updates to version 1.2.8 or later, which addresses the access control flaw through proper authentication checks and authorization validation. System administrators should also implement additional security measures such as restricting access to the wp-admin/admin-ajax.php endpoint through firewall rules, monitoring for unusual AJAX requests, and conducting regular security audits of installed plugins. The vulnerability demonstrates the importance of proper input validation and authorization checks in web applications, as outlined in OWASP Top 10 2017 category A07: Identification and Authentication Failures, where inadequate access control mechanisms can lead to complete system compromise. Organizations should also consider implementing Web Application Firewalls to detect and block malicious AJAX requests targeting known vulnerable endpoints, and maintain comprehensive backup strategies to quickly restore compromised themes and files.