CVE-2018-20987 in newsletters-lite Plugin
Summary
by MITRE
The newsletters-lite plugin before 4.6.8.6 for WordPress has PHP object injection.
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Analysis
by VulDB Data Team • 12/01/2023
The CVE-2018-20987 vulnerability represents a critical PHP object injection flaw discovered in the newsletters-lite plugin for WordPress, affecting versions prior to 4.6.8.6. This vulnerability resides within the plugin's handling of serialized PHP objects, creating a dangerous attack vector that can be exploited by malicious actors to execute arbitrary code on vulnerable WordPress installations. The issue stems from insufficient input validation and sanitization mechanisms within the plugin's core functionality, specifically when processing user-supplied data that gets unserialized without proper security checks.
The technical exploitation of this vulnerability occurs through the manipulation of serialized PHP objects that are passed to the plugin's processing functions. When an attacker crafts malicious serialized data and injects it into the plugin's parameters, the vulnerable code performs an unserialize operation without adequate validation, allowing the attacker to control the object instantiation process. This creates opportunities for remote code execution, data manipulation, and potential privilege escalation within the WordPress environment. The vulnerability aligns with CWE-502, which specifically addresses unsafe deserialization of untrusted data, and follows patterns commonly seen in PHP object injection attacks that leverage the unserialize() function's behavior.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and data breach potential. Attackers can leverage this flaw to gain unauthorized access to WordPress installations, potentially leading to full administrative control over the affected websites. The vulnerability affects not only individual blog posts but can also compromise entire WordPress networks, especially in multi-site configurations where the plugin is widely deployed. Additionally, the attack surface is broad as the vulnerability can be exploited through various entry points including contact forms, newsletter subscription mechanisms, or any interface that processes user input through the vulnerable plugin. This makes the exploitation particularly dangerous in environments where multiple users interact with the WordPress platform, as the attack can be initiated through seemingly benign user activities.
Mitigation strategies for CVE-2018-20987 should prioritize immediate plugin updates to version 4.6.8.6 or later, which contain the necessary patches to address the object injection vulnerability. Security administrators should also implement additional protective measures including input validation at multiple layers, regular security audits of WordPress plugins, and monitoring for suspicious activity patterns that may indicate exploitation attempts. The vulnerability demonstrates the importance of following secure coding practices, particularly around the handling of serialized data and the principle of least privilege in plugin development. Organizations should consider implementing web application firewalls to detect and block malicious serialized object patterns, while also establishing robust incident response procedures to quickly address potential exploitation attempts. The attack vectors associated with this vulnerability align with ATT&CK technique T1059.007 for PHP, emphasizing the need for comprehensive security controls that address both the immediate vulnerability and broader application security posture.