CVE-2021-24282 in Redirection for Contact Form 7 Plugin
Summary
by MITRE • 05/14/2021
In the Redirection for Contact Form 7 WordPress plugin before 2.3.4, any authenticated user, such as a subscriber, could use the various AJAX actions in the plugin to do a variety of things. For example, an attacker could use wpcf7r_reset_settings to reset the plugin’s settings, wpcf7r_add_action to add actions to a form, and more.
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Analysis
by VulDB Data Team • 05/16/2021
The vulnerability identified as CVE-2021-24282 affects the Redirection for Contact Form 7 WordPress plugin, specifically versions prior to 2.3.4, presenting a significant authorization flaw that allows authenticated users to execute privileged operations through exposed AJAX endpoints. This issue stems from insufficient access control mechanisms within the plugin's AJAX handling system, where the security checks fail to properly validate user permissions before executing sensitive administrative functions. The vulnerability operates under CWE-285, which classifies it as an authorization flaw, specifically involving improper access control in web applications. Attackers leveraging this weakness can escalate their privileges from subscriber-level access to perform actions typically restricted to administrators or editors, creating a serious privilege escalation vector within WordPress environments.
The technical implementation of this vulnerability involves the plugin's AJAX actions being accessible without proper authentication verification, allowing any authenticated user to invoke functions such as wpcf7r_reset_settings that can reset all plugin configurations, wpcf7r_add_action that can inject arbitrary actions into contact forms, and other administrative functions. These AJAX endpoints lack proper capability checks, meaning they execute with elevated privileges regardless of the user's actual role within the WordPress system. The flaw essentially creates a backdoor through which any registered user can manipulate plugin settings and potentially compromise the integrity of contact forms, which could lead to data exfiltration, service disruption, or further attack vectors. This type of vulnerability aligns with ATT&CK technique T1078.004, which covers valid accounts used for unauthorized access, as it exploits the legitimate access of authenticated users to perform malicious activities.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can enable attackers to fundamentally alter the behavior of contact forms and potentially redirect form submissions to malicious endpoints. When an attacker can reset plugin settings, they may inadvertently disable security features or reconfigure the plugin to redirect submissions to attacker-controlled servers. The ability to add actions to forms through wpcf7r_add_action creates a persistent threat vector where malicious code can be injected into legitimate form processing workflows, potentially leading to data theft or server compromise. This vulnerability also increases the risk of denial of service attacks, as attackers could disable or corrupt form functionality, making it impossible for legitimate users to submit contact information. Organizations running vulnerable versions of this plugin face a heightened risk of data exposure and service disruption, particularly in environments where contact forms are critical for business operations or contain sensitive user information.
Mitigation strategies for CVE-2021-24282 should prioritize immediate patching to version 2.3.4 or later, which addresses the core authorization flaw by implementing proper capability checks for all AJAX endpoints. System administrators should also implement network-level restrictions to limit access to plugin AJAX endpoints to trusted IP addresses or implement additional authentication layers. The WordPress security team recommends enabling two-factor authentication for all administrative accounts and regularly auditing user roles and capabilities to ensure that only authorized personnel have elevated privileges. Organizations should also monitor their WordPress installations for similar vulnerabilities by conducting regular security assessments and implementing automated scanning tools that can detect unauthorized access to plugin endpoints. The remediation process should include verifying that all plugin updates are properly installed and that no legacy code remains in the system that could introduce similar authorization flaws. Additionally, implementing web application firewalls and security monitoring solutions can help detect and prevent exploitation attempts of this vulnerability, while regular security training for administrators can help prevent social engineering attacks that might leverage this weakness.