CVE-2020-8772: InfiniteWP Client Auth Bypass Vulnerability

CVE-2020-8772 Overview

CVE-2020-8772 is a critical authentication bypass vulnerability in the InfiniteWP Client plugin for WordPress. The vulnerability exists due to a missing authorization check in the iwp_mmb_set_request function within init.php. This flaw allows any attacker who knows the username of an administrator to log in to the WordPress site without providing valid credentials.

Critical Impact

Attackers can gain full administrative access to WordPress sites by simply knowing an administrator username, bypassing all authentication controls and potentially compromising the entire website.

Affected Products

• InfiniteWP Client plugin versions prior to 1.9.4.5
• WordPress installations using vulnerable InfiniteWP Client versions
• Revmakx InfiniteWP Client for WordPress

Discovery Timeline

• 2020-02-06 - CVE-2020-8772 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-8772

Vulnerability Analysis

This vulnerability is classified as CWE-862: Missing Authorization. The InfiniteWP Client plugin fails to properly validate authorization when processing requests through the iwp_mmb_set_request function. This function is responsible for handling remote management requests but lacks the necessary checks to verify that the requester has legitimate access rights.

The vulnerability is particularly dangerous because it requires no special privileges or user interaction to exploit. An attacker operating over the network can craft malicious requests that bypass authentication entirely. The only prerequisite is knowledge of a valid administrator username, which can often be enumerated or discovered through various means on WordPress installations.

Root Cause

The root cause of this vulnerability lies in the missing authorization check within the iwp_mmb_set_request function in init.php. The function processes incoming requests without adequately verifying whether the request originates from an authenticated and authorized source. This design flaw allows unauthenticated attackers to impersonate legitimate administrators by simply providing a valid username, completely circumventing WordPress's authentication mechanisms.

Attack Vector

The attack vector for CVE-2020-8772 is network-based, requiring no user interaction or special privileges. An attacker can exploit this vulnerability by sending specially crafted HTTP requests to the vulnerable WordPress installation. The exploitation process involves:

1. Identifying a target WordPress site running a vulnerable version of InfiniteWP Client
2. Enumerating or obtaining a valid administrator username (often admin or discoverable through author archives)
3. Sending a malicious request to the iwp_mmb_set_request function with the administrator username
4. Gaining unauthorized administrative access to the WordPress dashboard

The vulnerability mechanism centers on the lack of proper authentication validation in the InfiniteWP Client's request handling logic. When the plugin receives a management request, it fails to verify that the request includes valid authentication credentials. For detailed technical analysis, refer to the WebARX Security Blog Post documenting this vulnerability.

Detection Methods for CVE-2020-8772

Indicators of Compromise

• Unexpected administrator login events without corresponding legitimate login attempts
• Suspicious requests to the InfiniteWP Client plugin endpoints in web server access logs
• New administrator accounts or modified user privileges without authorization
• Unusual plugin installations, theme changes, or site configuration modifications

Detection Strategies

• Monitor WordPress authentication logs for login events from unexpected IP addresses or at unusual times
• Analyze web server access logs for requests targeting InfiniteWP Client endpoints containing administrator usernames
• Implement Web Application Firewall (WAF) rules to detect and block exploitation attempts against known vulnerable endpoints
• Deploy file integrity monitoring to detect unauthorized changes to WordPress core files, plugins, or themes

Monitoring Recommendations

• Enable detailed WordPress audit logging to capture all authentication events and administrative actions
• Configure real-time alerting for administrator logins from new IP addresses or geographic locations
• Regularly review access logs for patterns consistent with automated scanning or exploitation attempts
• Monitor for new user account creation or privilege escalation events

How to Mitigate CVE-2020-8772

Immediate Actions Required

• Update the InfiniteWP Client plugin to version 1.9.4.5 or later immediately
• Audit recent administrator login history for any suspicious or unauthorized access
• Review and verify all administrator accounts and user privileges on affected WordPress installations
• Check for any unauthorized changes to site content, plugins, themes, or configurations

Patch Information

The vulnerability has been addressed in InfiniteWP Client version 1.9.4.5. Organizations should update to this version or later through the WordPress plugin update mechanism. Additional information about this vulnerability can be found at WPVulnDB Vulnerability #10011.

Workarounds

• Temporarily disable the InfiniteWP Client plugin if immediate patching is not possible
• Implement IP-based access restrictions to limit access to WordPress administrative endpoints
• Deploy a Web Application Firewall (WAF) with rules to detect and block exploitation attempts
• Consider using two-factor authentication (2FA) as an additional layer of protection for administrator accounts

# Configuration example
# Temporarily disable InfiniteWP Client plugin via WP-CLI
wp plugin deactivate jeremylewis/jeremylewis/infinitewp-client --path=/var/www/html

# Check current plugin version
wp plugin get infinitewp-client --field=version --path=/var/www/html

# Update to patched version
wp plugin update infinitewp-client --path=/var/www/html