CVE-2018-0587 in Ultimate Member Plugin
Summary
by MITRE
Unrestricted file upload vulnerability in Ultimate Member plugin prior to version 2.0.4 for WordPress allows remote authenticated users to upload arbitrary image files via unspecified vectors.
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Analysis
by VulDB Data Team • 02/05/2020
The CVE-2018-0587 vulnerability represents a critical unrestricted file upload flaw within the Ultimate Member WordPress plugin, affecting versions prior to 2.0.4. This vulnerability resides in the plugin's file handling mechanisms and specifically targets authenticated users who possess valid credentials within the WordPress environment. The flaw allows attackers to bypass normal file upload restrictions and potentially execute malicious code through image files, creating a significant security risk for WordPress sites utilizing this plugin. The vulnerability's impact extends beyond simple file uploads as it enables attackers to gain persistent access to affected systems through crafted malicious files.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the plugin's file upload functionality. Attackers can exploit this weakness by uploading malicious files that appear to be legitimate image formats but contain executable code or malicious payloads. The unspecified vectors mentioned in the description suggest that the vulnerability may exist across multiple upload points within the plugin's user profile or media handling features. This weakness aligns with CWE-434 which specifically addresses the improper restriction of uploads of executable code, and represents a classic example of insecure file upload vulnerabilities that have been documented extensively in the cybersecurity community. The vulnerability operates under the principle that the system fails to properly validate file types and content, allowing attackers to upload files with potentially dangerous extensions or content that can be executed by the web server.
From an operational perspective, this vulnerability creates a severe threat landscape for WordPress administrators and end users. Authenticated attackers with valid user credentials can leverage this flaw to upload malicious files that may contain web shells, backdoors, or other malicious code that can be executed on the target server. The implications extend to potential data exfiltration, system compromise, and the ability to establish persistent access to the compromised WordPress installation. This vulnerability directly impacts the principle of least privilege as it allows authenticated users to escalate their privileges beyond normal user boundaries. The attack surface includes not only the immediate compromise of individual user accounts but also the potential for broader system infiltration and lateral movement within the network. According to ATT&CK framework, this vulnerability maps to T1078 Valid Accounts and T1059 Command and Scripting Interpreter, as attackers can leverage legitimate accounts to upload malicious files and execute code on the target system.
The mitigation strategies for CVE-2018-0587 primarily focus on immediate plugin updates to version 2.0.4 or later, which contains the necessary patches to address the unrestricted file upload vulnerability. Organizations should implement additional security controls including file type validation, content inspection, and proper file upload restrictions. The implementation of web application firewalls and security monitoring systems can help detect and prevent exploitation attempts. Network segmentation and access controls should be reinforced to limit the potential impact of successful exploitation. Regular security audits and vulnerability assessments should be conducted to identify similar weaknesses in other plugins and themes. The vulnerability underscores the importance of maintaining up-to-date software and implementing proper security hygiene practices. Security teams should also consider implementing automated patch management processes to ensure timely deployment of security updates across all WordPress installations. Additionally, the principle of defense in depth should be applied through multiple layers of security controls including file upload restrictions, content validation, and monitoring of suspicious file upload activities.