CVE-2021-42358 in Contact Form with Captcha Plugin
Summary
by MITRE • 11/29/2021
The Contact Form With Captcha WordPress plugin is vulnerable to Cross-Site Request Forgery due to missing nonce validation in the ~/cfwc-form.php file during contact form submission, which made it possible for attackers to inject arbitrary web scripts in versions up to, and including 1.6.2.
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Analysis
by VulDB Data Team • 12/02/2021
The vulnerability identified as CVE-2021-42358 affects the Contact Form With Captcha WordPress plugin, specifically targeting versions up to and including 1.6.2. This represents a critical security flaw that undermines the integrity of web applications by enabling unauthorized modifications through malicious request manipulation. The vulnerability stems from insufficient validation mechanisms within the plugin's core functionality, creating an exploitable condition that allows attackers to manipulate form submissions without proper authorization. The affected component resides in the cfwc-form.php file where the necessary security checks fail to validate the authenticity of incoming requests.
This vulnerability manifests as a cross-site request forgery issue that operates under CWE-352, which classifies CSRF as a weakness where an attacker can trick authenticated users into executing unwanted actions on a web application. The root cause lies in the absence of nonce validation during form processing, which is a fundamental security mechanism designed to prevent unauthorized requests from being processed. Without proper nonce verification, the plugin cannot distinguish between legitimate user submissions and maliciously crafted requests that attempt to exploit the form's functionality. The vulnerability creates a pathway for attackers to inject arbitrary web scripts, potentially leading to complete compromise of user sessions or unauthorized data manipulation.
The operational impact of this vulnerability extends beyond simple script injection, as it enables attackers to perform unauthorized actions within the context of authenticated users. When an attacker successfully exploits this CSRF vulnerability, they can manipulate contact form submissions to redirect users to malicious websites, harvest sensitive information, or even modify form configurations that could affect other users. The attack vector is particularly dangerous because it leverages the trust relationship between the user and the web application, making it difficult for users to detect malicious activity. The vulnerability affects all users who have access to the compromised WordPress site, potentially exposing sensitive data and undermining user trust in the application's security posture.
Mitigation strategies for CVE-2021-42358 require immediate attention through plugin updates to versions that implement proper nonce validation mechanisms. System administrators should prioritize upgrading to the latest available version of the Contact Form With Captcha plugin, as this directly addresses the missing validation checks in the cfwc-form.php file. Additionally, implementing proper input validation and output encoding practices can further reduce the attack surface. Security professionals should consider deploying web application firewalls that can detect and block suspicious request patterns associated with CSRF attacks. The implementation of Content Security Policy headers can provide additional protection against script injection attempts, while regular security audits of WordPress plugins can help identify similar vulnerabilities before they can be exploited. Organizations should also establish monitoring procedures to detect unusual form submission patterns that might indicate CSRF attack attempts, ensuring comprehensive protection against this class of vulnerability that aligns with ATT&CK technique T1566.001 for credential access through social engineering attacks.