CVE-2024-4704: Contact Form 7 Open Redirect Vulnerability

CVE-2024-4704 Overview

CVE-2024-4704 is an open redirect vulnerability affecting the Contact Form 7 WordPress plugin versions prior to 5.9.5. This popular WordPress plugin, developed by Rocklobster, contains a flaw that allows attackers to craft malicious URLs that redirect users to attacker-controlled websites. Open redirect vulnerabilities are classified under CWE-601 (URL Redirection to Untrusted Site) and can be leveraged in phishing campaigns to increase the perceived legitimacy of malicious links.

Critical Impact

Attackers can abuse the trusted domain reputation of WordPress sites using Contact Form 7 to redirect users to malicious destinations, facilitating phishing attacks, credential theft, and malware distribution.

Affected Products

• Contact Form 7 WordPress plugin versions before 5.9.5
• WordPress installations running vulnerable Contact Form 7 versions
• Websites utilizing Rocklobster Contact Form 7 plugin

Discovery Timeline

• 2024-06-27 - CVE-2024-4704 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-4704

Vulnerability Analysis

This open redirect vulnerability exists due to insufficient validation of URL parameters within the Contact Form 7 plugin. The vulnerability allows network-based attacks that require user interaction, specifically tricking a user into clicking a crafted link. The changed scope indicates that successful exploitation can impact resources beyond the vulnerable component itself, potentially affecting the user's browser session on other domains.

The attack does not require any authentication or special privileges on the target WordPress site. When exploited, this vulnerability enables limited unauthorized access to confidential information and allows modification of data integrity, though it does not impact system availability.

Root Cause

The root cause of CVE-2024-4704 stems from improper input validation in URL handling within the Contact Form 7 plugin. The application fails to adequately validate and sanitize redirect URL parameters before processing, allowing external URLs to be injected. This implementation flaw enables attackers to construct URLs that appear to originate from the legitimate WordPress domain but ultimately redirect users to malicious external sites.

Attack Vector

The attack is conducted over the network and requires user interaction. An attacker crafts a specially constructed URL containing a malicious redirect destination within the Contact Form 7 endpoint. When an unsuspecting user clicks this link—often delivered via phishing emails or social engineering—they are first directed to the legitimate WordPress site before being automatically redirected to the attacker's chosen destination.

This technique is particularly effective because the initial URL displays a trusted domain, making it more likely that security-conscious users and email filters will allow the request. The vulnerability can be chained with other attacks, such as credential harvesting pages that mimic the target WordPress site's login interface.

Detection Methods for CVE-2024-4704

Indicators of Compromise

• Suspicious outbound redirects from Contact Form 7 plugin endpoints in web server access logs
• URL parameters containing external domain references in requests to the WordPress site
• User reports of unexpected redirects after clicking links that appear to point to your WordPress domain
• Increased bounce rates or unusual traffic patterns on pages utilizing Contact Form 7

Detection Strategies

• Monitor web application firewall (WAF) logs for requests containing external URLs in redirect parameters
• Implement URL parameter analysis to detect attempts to inject external domains
• Configure SIEM rules to alert on unusual redirect patterns originating from WordPress plugin endpoints
• Review access logs for requests to Contact Form 7 paths containing URL-encoded external destinations

Monitoring Recommendations

• Enable detailed logging for all Contact Form 7 related endpoints
• Configure alerting for any HTTP 3xx responses that redirect to external domains
• Implement real-time monitoring of outbound links generated by WordPress plugins
• Deploy endpoint detection solutions to identify users who may have been redirected to malicious sites

How to Mitigate CVE-2024-4704

Immediate Actions Required

• Update Contact Form 7 plugin to version 5.9.5 or later immediately
• Audit WordPress plugin inventory and identify all installations running vulnerable versions
• Review web server logs for evidence of exploitation attempts
• Notify users who may have been exposed to phishing links utilizing this vulnerability

Patch Information

The vulnerability has been addressed in Contact Form 7 version 5.9.5. Site administrators should update to this version or later through the WordPress plugin management interface or by manually downloading the patched version from the official WordPress plugin repository. For detailed technical information about this vulnerability, refer to the WPScan Vulnerability Report.

Workarounds

• Implement WAF rules to block requests containing external URLs in redirect parameters
• Temporarily disable Contact Form 7 until the patch can be applied if the risk is unacceptable
• Configure server-side URL validation to restrict redirect destinations to known safe domains
• Deploy browser-based security controls that warn users when leaving the trusted domain

# WordPress CLI command to update Contact Form 7
wp plugin update contact-form-7

# Verify the installed version after update
wp plugin list --name=contact-form-7 --fields=name,version,status

# Check for any other outdated plugins
wp plugin list --update=available --format=table