CVE-2024-34093

Executive Summary

CVE-2024-34093 is a security bypass vulnerability in Archer Platform 6 prior to version 2024.03. The flaw allows an unauthenticated attacker to bypass IP-based whitelisting by manipulating the X-Forwarded-For HTTP header. This header is commonly used by reverse proxies and load balancers to pass the original client IP address to the backend application. When the application trusts this header without proper validation, an attacker can spoof a trusted IP address and gain unauthorized access to restricted resources. The vulnerability has a CVSS score of 5.3 (Medium) and is classified under CWE-290 (Authentication Bypass by Spoofing). No public proof-of-concept or exploit code is currently available, and the EPSS score is 0.0%, indicating a low probability of exploitation in the wild. However, the attack vector is network-based, requires no authentication, and has low complexity, making it a potential target for automated scanning.

Supply Chain & Package Security

This vulnerability is not related to a package manager (NPM, PyPI, Go, Ruby) and does not involve a software supply chain component. It is a configuration and input validation issue in the Archer Platform application itself.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Base Score: 5.3 (Medium)
• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The vulnerable component and the impacted component are the same.
• Confidentiality (C): Low (L) – Limited information disclosure (bypassing whitelist may expose restricted functionality).
• Integrity (I): None (N) – No data modification.
• Availability (A): None (N) – No denial of service.

Threat Level: Medium. The vulnerability allows bypassing access controls but does not directly lead to data modification or system compromise. However, it could be chained with other vulnerabilities to escalate privileges.

Deep Dive & Mechanics

The Archer Platform uses IP-based whitelisting to restrict access to certain administrative or sensitive endpoints. When the X-Forwarded-For header is enabled (typically in a reverse proxy setup), the application reads the client IP from this header instead of the direct socket connection. The vulnerability arises because the application does not validate the authenticity of the X-Forwarded-For header. An attacker can send a crafted HTTP request with an X-Forwarded-For header set to a trusted IP address (e.g., 127.0.0.1 or an internal management IP). The application then treats the request as originating from that trusted IP, bypassing the whitelist.

Root Cause: The application trusts the X-Forwarded-For header without verifying that it was added by a trusted proxy. This is a classic case of improper input validation (CWE-290).

Attack Scenario:

1. The attacker identifies an Archer Platform instance that uses IP whitelisting.
2. The attacker sends a request to a protected endpoint (e.g., /admin) with the header X-Forwarded-For: 192.168.1.100 (a trusted IP).
3. The application reads the header and grants access, bypassing the whitelist.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

# Archer Platform 6 < 2024.03
def get_client_ip(request):
    # Trusts X-Forwarded-For without validation
    if 'X-Forwarded-For' in request.headers:
        return request.headers['X-Forwarded-For'].split(',')[0].strip()
    return request.remote_addr

def is_whitelisted(ip):
    return ip in WHITELIST

# In request handler
client_ip = get_client_ip(request)
if is_whitelisted(client_ip):
    # Grant access to protected resource
    return handle_admin_request()
else:
    return "Access Denied", 403

Patched Code (Conceptual):

# Archer Platform 2024.03+
def get_client_ip(request):
    # Only trust X-Forwarded-For from known proxies
    if 'X-Forwarded-For' in request.headers:
        # Validate that the request came through a trusted proxy
        if request.remote_addr in TRUSTED_PROXIES:
            return request.headers['X-Forwarded-For'].split(',')[0].strip()
        else:
            # Ignore header from untrusted sources
            return request.remote_addr
    return request.remote_addr

def is_whitelisted(ip):
    return ip in WHITELIST

# In request handler
client_ip = get_client_ip(request)
if is_whitelisted(client_ip):
    return handle_admin_request()
else:
    return "Access Denied", 403

The patch ensures that the X-Forwarded-For header is only trusted when the direct connection comes from a known, trusted proxy server. This prevents external attackers from spoofing the header.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Access to an Archer Platform 6 instance (version < 2024.03) with IP whitelisting enabled.
• Knowledge of a trusted IP address (e.g., internal management IP).

Exploitation Steps:

1. Identify the target endpoint that uses IP whitelisting (e.g., /admin, /api/restricted).
2. Send a crafted HTTP request with the X-Forwarded-For header set to a trusted IP.

Example using curl:

curl -H "X-Forwarded-For: 192.168.1.100" http://target-archer.com/admin

Example using Python:

import requests

url = "http://target-archer.com/admin"
headers = {"X-Forwarded-For": "192.168.1.100"}
response = requests.get(url, headers=headers)
print(response.text)

Expected Outcome: The application returns the admin interface instead of "Access Denied".

Blue Team (Defense & Detection)

Detection Strategy:

• Monitor for requests containing X-Forwarded-For headers from external IPs that are not behind a known proxy.
• Log and alert on access to protected endpoints where the X-Forwarded-For header differs from the actual source IP.

Lab Setup for Testing:

1. Deploy a vulnerable Archer Platform 6 instance in an isolated environment.
2. Configure IP whitelisting for a test endpoint.
3. Use a tool like Burp Suite or custom scripts to send spoofed requests.
4. Verify that the whitelist is bypassed.
5. Apply the patch (upgrade to 2024.03) and confirm the bypass is no longer possible.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to Archer Platform endpoints with an X-Forwarded-For header containing an internal or whitelisted IP address.
  • Requests from external IPs that result in access to restricted resources (e.g., /admin, /api/restricted).
• Log IOCs:
  • Application logs showing access to protected endpoints with an X-Forwarded-For IP that does not match the actual source IP.
  • Repeated attempts to access restricted resources with varying X-Forwarded-For values.
• File IOCs:
  • No specific file-based IOCs; this is a network-level bypass.

Detection Engineering

YARA Rule

rule CVE_2024_34093_Archer_XForwardedFor_Bypass {
    meta:
        description = "Detects attempts to exploit CVE-2024-34093 by spoofing X-Forwarded-For header"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-34093"
    strings:
        $header = "X-Forwarded-For"
        $admin_path = "/admin" nocase
        $api_path = "/api" nocase
    condition:
        any of ($header) and any of ($admin_path, $api_path)
}

Sigma Rule

title: Archer Platform X-Forwarded-For Header Bypass Attempt
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects HTTP requests to Archer Platform with spoofed X-Forwarded-For header targeting restricted endpoints
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: archer
detection:
    selection:
        http.method: GET
        http.url|contains:
            - '/admin'
            - '/api/restricted'
        http.headers|contains: 'X-Forwarded-For'
    condition: selection
falsepositives:
    - Legitimate proxy traffic
level: medium
tags:
    - attack.t1190
    - cve.2024.34093

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-34093 Archer X-Forwarded-For Bypass Attempt"; flow:to_server; http.method; content:"GET"; http.uri; content:"/admin"; nocase; http.header; content:"X-Forwarded-For"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade: Apply the official patch by upgrading to Archer Platform 2024.03 or later.
2. Disable X-Forwarded-For: If the feature is not required, disable the X-Forwarded-For header processing in the Archer configuration.
3. Network Segmentation: Ensure that the Archer Platform is not directly exposed to the internet. Place it behind a reverse proxy that strips or validates the X-Forwarded-For header.

Long-Term Mitigations:

• Implement a Web Application Firewall (WAF) rule to block requests where the X-Forwarded-For header contains internal IP ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) unless the request originates from a trusted proxy.
• Use mutual TLS (mTLS) or VPN for administrative access instead of IP whitelisting.
• Regularly audit application logs for anomalous access patterns.

Workaround (if patching is not immediately possible):

• Configure the reverse proxy to overwrite the X-Forwarded-For header with the actual client IP, preventing spoofing from the client side.

Valters IT
Securing Digital Frontiers