CVE-2023-5673 in WP Mail Log Plugin
Summary
by MITRE • 12/26/2023
The WP Mail Log WordPress plugin before 1.1.3 does not properly validate file extensions uploading files to attach to emails, allowing attackers to upload PHP files, leading to remote code execution.
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Analysis
by VulDB Data Team • 01/19/2024
The WP Mail Log WordPress plugin vulnerability CVE-2023-5673 represents a critical security flaw in versions prior to 1.1.3 that stems from inadequate input validation during file upload operations. This vulnerability resides in the plugin's email attachment handling mechanism where the system fails to properly validate file extensions before allowing uploads to be attached to outgoing emails. The flaw enables attackers to bypass security restrictions and upload malicious PHP files directly through the plugin's interface, creating a significant attack vector that can be exploited by unauthorized parties. The vulnerability is categorized under CWE-434 which specifically addresses "Unrestricted Upload of File with Dangerous Type" and aligns with ATT&CK technique T1190 for "Exploit Public-Facing Application" and T1505.003 for "Scheduled Task/Job" when considering potential post-exploitation activities.
The technical implementation of this vulnerability allows attackers to upload PHP files with extensions that are not properly filtered or validated by the plugin's upload mechanism. When users attempt to send emails through the WP Mail Log plugin, they can attach files that are processed without adequate sanitization of file extensions. This creates an opportunity for attackers to upload web shells or other malicious PHP scripts that can be executed on the web server hosting the WordPress installation. The flaw essentially removes the boundary checks that should prevent dangerous file types from being uploaded, enabling attackers to gain persistent access to the server through the uploaded PHP files. This represents a classic case of insecure file upload handling where the plugin's validation logic is insufficient to prevent the upload of executable code.
The operational impact of CVE-2023-5673 is severe and can lead to complete system compromise when exploited. Once an attacker successfully uploads a malicious PHP file through the vulnerable plugin, they can execute arbitrary code on the target server with the privileges of the web application. This typically results in unauthorized access to the entire WordPress installation, potential data exfiltration, and the ability to establish persistent backdoors. The vulnerability can be exploited remotely without requiring authentication, making it particularly dangerous as attackers can compromise systems from anywhere on the internet. The impact extends beyond the immediate plugin scope as compromised WordPress installations often serve as entry points for broader network infiltration, potentially affecting other systems within the same network infrastructure.
Mitigation strategies for CVE-2023-5673 should focus on immediate remediation through plugin updates to version 1.1.3 or later where the file extension validation has been properly implemented. System administrators should also implement additional security layers including web application firewalls that can detect and block suspicious file upload attempts, proper file type validation at multiple levels, and regular security audits of plugin installations. Organizations should conduct thorough vulnerability assessments to identify all instances of the vulnerable plugin across their infrastructure and ensure that proper file upload restrictions are in place. The remediation process should include not only updating the plugin but also reviewing and implementing proper input validation mechanisms that align with security best practices outlined in OWASP Top Ten and NIST cybersecurity guidelines. Additionally, implementing principle of least privilege for web server accounts and regular monitoring of uploaded files can significantly reduce the risk of exploitation.