CVE-2018-12426 in WP Live Chat Support
Summary
by MITRE
The WP Live Chat Support Pro plugin before 8.0.07 for WordPress is vulnerable to unauthenticated Remote Code Execution due to client-side validation of allowed file types, as demonstrated by a v1/remote_upload request with a .php filename and the image/jpeg content type.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 02/23/2020
The WP Live Chat Support Pro plugin for WordPress represents a critical security vulnerability that affects versions prior to 8.0.07, creating a significant risk for WordPress installations. This vulnerability stems from inadequate server-side validation mechanisms that fail to properly verify file types during the upload process, allowing malicious actors to bypass security controls through client-side manipulation. The flaw specifically manifests in the v1/remote_upload endpoint which accepts file uploads without sufficient validation of the actual file content, enabling attackers to upload malicious PHP files disguised with legitimate image extensions.
The technical implementation of this vulnerability demonstrates a classic case of insecure file upload handling where the plugin relies on client-side validation as the primary security control rather than implementing robust server-side verification. Attackers can exploit this by crafting a request to the v1/remote_upload endpoint with a filename ending in .php while setting the content type header to image/jpeg, effectively fooling the system into accepting the malicious payload. This approach leverages the principle of least privilege violation where the application fails to validate that the uploaded file's actual content matches its declared type, creating an attack surface that can be exploited without authentication.
The operational impact of this vulnerability extends far beyond simple data compromise, as it provides attackers with complete remote code execution capabilities on the affected WordPress server. Once a malicious PHP file is successfully uploaded through this vulnerability, attackers can execute arbitrary commands on the server, potentially leading to full system compromise, data exfiltration, or the installation of persistent backdoors. The unauthenticated nature of this exploit means that any user can trigger the vulnerability without requiring valid credentials, making it particularly dangerous for publicly accessible WordPress installations. This vulnerability directly aligns with CWE-434 which describes insecure file upload vulnerabilities where applications accept files without proper validation of their content, and it maps to attack techniques in the MITRE ATT&CK framework under T1190 for exploiting vulnerabilities in web applications.
Security practitioners must understand that this vulnerability represents a fundamental flaw in the plugin's architecture where the security model relies on client-side validation as the sole defense mechanism. The recommended mitigation strategy involves immediate upgrading to version 8.0.07 or later, which implements proper server-side validation of both file extensions and content types. Additionally, administrators should implement additional protective measures such as restricting file upload capabilities, monitoring upload directories for suspicious activity, and implementing web application firewalls to detect and block malicious upload attempts. The vulnerability highlights the critical importance of defense in depth principles where multiple layers of validation should be implemented rather than relying on a single security control mechanism. Organizations should also conduct comprehensive security assessments of their WordPress installations to identify similar vulnerabilities in other plugins and themes that may be susceptible to the same class of attack.