CVE-2021-4426 in Absolute Reviews Plugin
Summary
by MITRE • 07/12/2023
The Absolute Reviews plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 1.0.8. This is due to missing or incorrect nonce validation on the metabox_review_save() function. This makes it possible for unauthenticated attackers to save meta tags via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
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Analysis
by VulDB Data Team • 07/12/2023
The Absolute Reviews plugin for WordPress presents a critical cross-site request forgery vulnerability that affects versions up to and including 1.0.8. This vulnerability stems from inadequate security controls within the plugin's metabox_review_save() function, which fails to properly validate nonces. The absence of proper nonce verification creates a pathway for malicious actors to manipulate the plugin's functionality without authentication. The vulnerability operates under the principle that an attacker can craft a malicious request that appears legitimate to the WordPress system, thereby bypassing standard authentication mechanisms that would normally prevent unauthorized modifications.
The technical flaw manifests in the plugin's failure to implement proper nonce validation during the review saving process. Nonces serve as cryptographic tokens that ensure requests originate from authenticated users and prevent unauthorized modifications to WordPress data. In this case, the metabox_review_save() function lacks the necessary verification steps that would confirm the legitimacy of incoming requests. This weakness allows attackers to submit forged requests that manipulate meta tags within the WordPress environment, effectively enabling them to inject arbitrary data or modify existing review information. The vulnerability specifically targets the plugin's administrative functionality and represents a direct violation of the principle of least privilege.
The operational impact of this CSRF vulnerability extends beyond simple data manipulation to potentially compromise the integrity of review content and metadata within WordPress installations. An attacker who successfully exploits this vulnerability can alter review information, inject malicious meta tags, or modify existing review data without requiring authentication credentials. This creates a significant risk for websites that rely on user-generated content, as it allows attackers to manipulate the perceived credibility of reviews. The vulnerability particularly affects sites where administrators regularly interact with the plugin's metabox interface, making it more susceptible to social engineering attacks that trick administrators into executing malicious requests through crafted links or embedded content.
The exploitation of this vulnerability aligns with common CSRF attack patterns documented in the ATT&CK framework under the technique of "T1566: Phishing" and "T1071.004: Application Layer Protocol: DNS". Attackers typically leverage social engineering tactics to convince administrators to click malicious links that automatically submit forged requests to the vulnerable plugin endpoint. This attack vector represents a classic example of how seemingly minor security oversights in plugin development can create significant operational risks. Organizations using the Absolute Reviews plugin are particularly vulnerable because the attack requires minimal technical expertise and can be executed through simple web-based interactions.
Security mitigation strategies for this vulnerability should prioritize immediate plugin updates to versions that address the nonce validation issue. System administrators should implement additional security measures including regular security audits of installed plugins, monitoring for unauthorized modifications to review data, and implementing content security policies that limit the execution of potentially malicious requests. The vulnerability demonstrates the importance of proper input validation and authentication mechanisms in web applications, aligning with CWE-352 which specifically addresses cross-site request forgery weaknesses. Organizations should also consider implementing web application firewalls and monitoring solutions that can detect and prevent CSRF attacks targeting WordPress plugins. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other plugins or custom WordPress functionality that might present similar security risks.