CVE-2020-4074: PrestaShop Auth Bypass Vulnerability

CVE-2020-4074 Overview

CVE-2020-4074 is an authentication bypass vulnerability in PrestaShop, a popular open-source e-commerce platform. The vulnerability exists in versions from 1.5.0.0 up to (but not including) 1.7.6.6. Due to a malformed authentication system, attackers can forge requests and execute administrative commands without proper authorization, potentially leading to complete compromise of affected PrestaShop installations.

Critical Impact

Unauthenticated attackers can forge requests to execute admin commands, potentially taking full control of PrestaShop e-commerce stores, accessing customer data, and manipulating transactions.

Affected Products

• PrestaShop versions 1.5.0.0 through 1.7.6.5
• All PrestaShop deployments running vulnerable versions
• E-commerce stores using PrestaShop as their platform

Discovery Timeline

• 2020-07-02 - CVE-2020-4074 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-4074

Vulnerability Analysis

This vulnerability is classified as CWE-287 (Improper Authentication). The authentication system in PrestaShop contained a fundamental flaw that allowed attackers to bypass authentication controls. The vulnerability enables unauthenticated network-based attacks that require no user interaction and no special privileges, making it particularly dangerous for publicly accessible e-commerce installations.

The flaw resides in how PrestaShop handles session registration and cookie validation. Without proper session binding and validation, attackers could craft malicious requests that the system would interpret as authenticated administrative actions.

Root Cause

The root cause stems from improper session management within the authentication subsystem. The Cookie and Context classes did not properly register and validate session tokens when establishing authenticated sessions. This allowed attackers to forge requests that bypassed the intended authentication flow. The fix introduced proper session registration using a CustomerSession object and added necessary security imports to the cookie handling class.

Attack Vector

The attack is network-based and can be executed remotely against any publicly accessible PrestaShop installation. An attacker does not need any prior authentication or privileges to exploit this vulnerability. The attack requires no user interaction, meaning it can be fully automated. By forging HTTP requests with manipulated session data, attackers can execute administrative commands, potentially leading to complete takeover of the e-commerce platform.

// Security patch excerpt from classes/Context.php
// Source: https://github.com/PrestaShop/PrestaShop/commit/30b6a7bdaca9cb940d3ce462906dbb062499fc30
         $this->cookie->id_cart = (int) $this->cart->id;
         $this->cookie->write();
         $this->cart->autosetProductAddress();
+
+        $this->cookie->registerSession(new CustomerSession());
     }

     /**

The patch adds proper session registration using CustomerSession() to ensure authenticated sessions are properly bound and validated.

// Security patch excerpt from classes/Cookie.php
// Source: https://github.com/PrestaShop/PrestaShop/commit/30b6a7bdaca9cb940d3ce462906dbb062499fc30
  * International Registered Trademark & Property of PrestaShop SA
  */
 use Defuse\Crypto\Key;
+use PrestaShop\PrestaShop\Core\Exception\CoreException;
+use PrestaShop\PrestaShop\Core\Session\SessionInterface;

class CookieCore
{

The Cookie class now imports the necessary session interface to properly validate session authenticity.

Detection Methods for CVE-2020-4074

Indicators of Compromise

• Unusual administrative actions in PrestaShop logs without corresponding admin login events
• HTTP requests to admin endpoints from unexpected IP addresses or user agents
• Database modifications (orders, customers, products) without matching admin session records
• Anomalous cookie patterns or malformed session tokens in web server logs

Detection Strategies

• Monitor web server access logs for requests to /admin*/ endpoints without valid session establishment
• Implement web application firewall (WAF) rules to detect request forgery attempts
• Review PrestaShop admin activity logs for actions that don't correlate with legitimate admin sessions
• Deploy network intrusion detection signatures for suspicious authentication bypass patterns

Monitoring Recommendations

• Enable verbose logging for PrestaShop authentication events
• Configure alerts for administrative actions from new or unexpected source IPs
• Monitor for bulk or automated requests to administrative endpoints
• Implement real-time log analysis for authentication anomalies

How to Mitigate CVE-2020-4074

Immediate Actions Required

• Upgrade PrestaShop to version 1.7.6.6 or later immediately
• Audit administrative actions taken during the vulnerable period
• Review user accounts for any unauthorized additions or modifications
• Check for any unauthorized changes to store configuration, products, or payment settings

Patch Information

PrestaShop has released version 1.7.6.6 which addresses this vulnerability. The fix is available in the official security commit. The patch introduces proper session registration through the CustomerSession class and adds the necessary session interface imports to the Cookie class for proper authentication validation.

For detailed information about this vulnerability, refer to the GitHub Security Advisory GHSA-ccvh-jh5x-mpg4.

Workarounds

• Place the PrestaShop admin panel behind a VPN or IP whitelist if immediate patching is not possible
• Implement additional authentication layers (e.g., HTTP Basic Auth) in front of the admin directory
• Deploy a Web Application Firewall (WAF) with rules to filter suspicious authentication attempts
• Temporarily restrict network access to the PrestaShop admin panel until the patch can be applied

# Configuration example: Restrict admin access by IP in Apache .htaccess
# Place this in your PrestaShop admin directory
<Directory "/var/www/html/prestashop/admin*">
    Order Deny,Allow
    Deny from all
    Allow from 192.168.1.0/24
    Allow from 10.0.0.0/8
</Directory>