Horizon Alert
Summary of the vulnerability and why it matters
This advisory details a vulnerability in Nginx Proxy Manager, a technology used for managing network traffic and proxies. The issue involves inadequate protection against repeated attempts to guess user credentials and two-factor authentication codes, potentially allowing unauthorized access to administrative controls. The main concern is confirming relevance and exposure of this technology within our environment.
- Unlimited password guesses allowed.
- Allows unauthorized administrative access.
- Confirm if Nginx Proxy Manager is in use.
Attack Path
How an attacker could exploit the issue
An attacker could begin by targeting the Nginx Proxy Manager instance, which is often exposed to the internet for remote management. The attacker would then attempt to guess login credentials for any account by repeatedly sending requests to an authentication endpoint without being blocked. Once a valid login is achieved, the attacker could then attempt to guess a second factor of authentication (like a TOTP code) for that same account through another endpoint. Successful brute-forcing of both steps would grant the attacker administrative control over the system.
- Attack starts with network access.
- Authentication endpoints are brute-forced.
- Risk is full administrative control.
Live Threat
Current exploitation, exposure, and threat context
This vulnerability could allow an unauthenticated attacker to repeatedly guess login credentials and two-factor authentication codes for any user account. Successful guessing could lead to full administrative control of the Nginx Proxy Manager.
- Administrative access and session control.
- Brute-forcing credentials and TOTP codes.
- Full administrative control of the service.
Operational Fix
Recommended remediation, mitigation, and detection steps
For this critical vulnerability in Nginx Proxy Manager's authentication endpoints, the primary responsibility likely falls to the Application Owners or Platform Teams managing the Nginx Proxy Manager instance. The first practical step is to inventory all Nginx Proxy Manager deployments, confirm their exposure to the internet, and assess business criticality to prioritize remediation efforts.
- Application owners should address the issue.
- Verify external access and business criticality first.
- Plan remediation based on validated risk.
