CVE-2025-54833

Executive Summary

CVE-2025-54833 is a security advisory affecting OPEXUS FOIAXpress Public Access Link (PAL) version v11.1.0. The vulnerability allows unauthenticated remote attackers to bypass account-lockout and CAPTCHA protections, enabling more efficient brute-force password attacks. This weakness stems from improper restriction of excessive authentication attempts (CWE-307). With a CVSS score of 5.3 (Medium), the primary risk is unauthorized access to user accounts, potentially exposing sensitive FOIA-related data. No public exploit code or patch details are currently available, and the EPSS score is 0.0%, indicating low exploitation likelihood at this time.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a web application vulnerability in a proprietary OPEXUS product.

CVSS Breakdown & Threat Level

• CVSS Score: 5.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Attack Vector: Network (AV:N) – exploitable remotely.
• Attack Complexity: Low (AC:L) – no special conditions required.
• Privileges Required: None (PR:N) – unauthenticated.
• User Interaction: None (UI:N) – no user action needed.
• Scope: Unchanged (S:U) – vulnerability does not affect other components.
• Confidentiality Impact: Low (C:L) – limited information disclosure via brute-forced credentials.
• Integrity Impact: None (I:N) – no data modification.
• Availability Impact: None (A:N) – no denial of service.

Threat Level: Medium. While the CVSS score is moderate, the bypass of account-lockout and CAPTCHA significantly increases brute-force efficiency, potentially leading to account compromise.

Deep Dive & Mechanics

The vulnerability resides in the authentication mechanism of OPEXUS FOIAXpress PAL v11.1.0. The application fails to enforce rate limiting, account lockout after failed attempts, or CAPTCHA verification. This allows an attacker to send unlimited login requests without triggering any defensive measures.

Attack Flow:

1. Attacker identifies the login endpoint (e.g., /login or /api/auth).
2. Attacker uses a wordlist of common passwords or a targeted list.
3. Attacker sends repeated POST requests with different passwords for a known username.
4. The server processes each request without blocking or slowing down.
5. Upon successful authentication, the attacker gains access to the user's account.

Root Cause: Missing implementation of account lockout policies and CAPTCHA integration in the authentication logic.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable behavior.

Vulnerable Code (Conceptual):

# Vulnerable authentication endpoint
@app.route('/login', methods=['POST'])
def login():
    username = request.form['username']
    password = request.form['password']
    user = User.query.filter_by(username=username).first()
    if user and check_password(user.password, password):
        return jsonify(success=True, token=generate_token(user))
    else:
        return jsonify(success=False, error="Invalid credentials"), 401

No rate limiting, no lockout, no CAPTCHA.

Patched Code (Expected):

# Patched authentication endpoint with rate limiting and CAPTCHA
from flask_limiter import Limiter
from flask_limiter.util import get_remote_address

limiter = Limiter(key_func=get_remote_address)

@app.route('/login', methods=['POST'])
@limiter.limit("5 per minute")
def login():
    # Verify CAPTCHA token
    captcha_token = request.form.get('captcha_token')
    if not verify_captcha(captcha_token):
        return jsonify(success=False, error="CAPTCHA failed"), 403
    
    username = request.form['username']
    password = request.form['password']
    user = User.query.filter_by(username=username).first()
    if user and check_password(user.password, password):
        return jsonify(success=True, token=generate_token(user))
    else:
        # Increment failed attempts for account lockout
        increment_failed_attempts(username)
        if get_failed_attempts(username) >= 5:
            lock_account(username)
        return jsonify(success=False, error="Invalid credentials"), 401

Exploitation & Lab Setup

Red Team (Attacker)

Lab Setup:

1. Deploy OPEXUS FOIAXpress PAL v11.1.0 in a controlled environment.
2. Create a test user account with a weak password (e.g., password123).
3. Use a tool like Hydra or Burp Suite Intruder to brute-force the login.

Exploitation Steps:

1. Identify the login endpoint (e.g., https://target/login).
2. Use Hydra to brute-force:

   hydra -l admin -P /usr/share/wordlists/rockyou.txt target.com https-post-form "/login:username=^USER^&password=^PASS^:Invalid credentials"
   

3. Observe that no lockout or CAPTCHA occurs after multiple attempts.
4. Upon success, capture the session token and access the application.

No public exploit code is available.

Blue Team (Defender)

Detection Steps:

1. Monitor for excessive failed login attempts from a single IP address.
2. Alert on login requests without CAPTCHA tokens (if CAPTCHA is expected).
3. Use WAF rules to rate-limit login endpoints.

Hunting Query (Splunk):

index=web_logs sourcetype=access_combined
| search "/login" status=401
| stats count by clientip, username
| where count > 10

Indicators of Compromise (IOCs)

• Network IOCs:
  • High volume of POST requests to /login or /api/auth from a single IP.
  • Repeated HTTP 401 responses for the same username.
• Host IOCs:
  • Log entries showing multiple failed login attempts without lockout.
  • Unusual session tokens generated after brute-force success.
• File IOCs:
  • No specific file-based IOCs.

Detection Engineering

YARA Rule

rule CVE_2025_54833_bruteforce {
    meta:
        description = "Detects brute-force attempts against OPEXUS FOIAXpress PAL login"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-54833"
    strings:
        $login_endpoint = "/login"
        $failed_auth = "Invalid credentials"
        $post_method = "POST"
    condition:
        # of ($login_endpoint) > 10 and # of ($failed_auth) > 10 and $post_method
}

Sigma Rule

title: CVE-2025-54833 - Brute-Force Against OPEXUS FOIAXpress PAL
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects multiple failed login attempts indicating brute-force attack
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/login'
        sc-status: 401
    condition: selection | count() by src_ip > 10
falsepositives:
    - Legitimate users forgetting passwords
level: medium

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (msg:"CVE-2025-54833 - Brute-Force Attempt on OPEXUS FOIAXpress PAL"; flow:to_server,established; content:"POST"; http_method; content:"/login"; http_uri; content:"Invalid credentials"; http_server_body; threshold:type both, track by_src, count 10, seconds 60; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Public Access: If possible, restrict access to the PAL interface to trusted IPs via firewall or VPN.
2. Implement Rate Limiting: Use a WAF or reverse proxy (e.g., Nginx, Cloudflare) to limit login attempts per IP.
3. Enable CAPTCHA: Integrate reCAPTCHA or similar on the login page.
4. Account Lockout: Enforce account lockout after 5 failed attempts for 15 minutes.

Long-Term Fix:

• Apply vendor patch when available.
• Upgrade to a patched version of FOIAXpress PAL.
• Conduct a security audit of authentication mechanisms.

Workaround:

• Use multi-factor authentication (MFA) if supported.
• Monitor logs for brute-force patterns and block offending IPs.

Report generated by Valters IT DevSecOps & CTI Division