threat-modeling.md

Threat Model Analysis for fatedier/frp

Threat: frps Authentication Bypass

• Threat: frps Authentication Bypass

  • Description: An attacker bypasses the authentication mechanism of the frps server. This could be achieved through exploiting a vulnerability in the authentication logic, guessing weak credentials, or leveraging leaked credentials. The attacker might use brute-force attacks, dictionary attacks, or exploit vulnerabilities like improper handling of authentication tokens.
  • Impact: The attacker gains full control over the frps server, allowing them to view all connected clients, intercept/modify/redirect traffic, and potentially use the server as a pivot point for further attacks. This is a complete compromise of the frp infrastructure.
  • Affected frp Component: frps server, specifically the authentication handling within the control.go and related files (handling user login and token validation).
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Strong Passwords/Tokens: Enforce strong, unique passwords or use token-based authentication with long, randomly generated tokens. Disable default credentials.
    • Rate Limiting: Implement rate limiting on authentication attempts to prevent brute-force attacks. frp's configuration can help with this.
    • Account Lockout: Implement account lockout policies after a certain number of failed login attempts.
    • Multi-Factor Authentication (MFA): While frp doesn't natively support MFA, consider implementing it at the network or system level (e.g., SSH with MFA for server access).
    • Regular Security Audits: Regularly audit the frps configuration and authentication logs.
    • Vulnerability Scanning and Patching: Regularly scan for vulnerabilities and apply security updates to frps.

Threat: frps Denial of Service (DoS)

• Threat: frps Denial of Service (DoS)

  • Description: An attacker floods the frps server with a large number of connection requests, exceeding its capacity to handle legitimate traffic. This could involve SYN floods, UDP floods, or application-layer attacks targeting frp's specific protocols.
  • Impact: All services exposed through the frps server become unavailable to legitimate users. This disrupts business operations and can cause significant downtime.
  • Affected frp Component: frps server, specifically the network handling and connection management components (likely within server.go and related networking code).
  • Risk Severity: High
  • Mitigation Strategies:
    • Rate Limiting (Connection Level): Configure frps to limit the number of connections per client IP address or globally using max_pool_count and related settings.
    • Resource Limits (OS Level): Configure operating system-level resource limits (e.g., ulimit on Linux) to prevent frps from consuming excessive CPU, memory, or file descriptors.
    • Firewall Rules: Implement firewall rules to block or rate-limit traffic from known malicious sources or suspicious IP ranges.
    • DDoS Protection Services: Utilize cloud-based DDoS protection services to mitigate large-scale, distributed attacks.
    • Monitoring and Alerting: Implement monitoring to detect and alert on high connection rates or resource utilization.

Threat: Man-in-the-Middle (MitM) Attack (without TLS)

• Threat: Man-in-the-Middle (MitM) Attack (without TLS)

  • Description: An attacker intercepts the communication between frpc and frps. If TLS is not properly configured or is disabled, the attacker can eavesdrop on the traffic, modify data in transit, and potentially inject malicious commands. This requires the attacker to be positioned on the network path between the client and server.
  • Impact: Complete compromise of the confidentiality and integrity of the communication. The attacker can steal sensitive data, inject malicious code, or redirect traffic to malicious servers.
  • Affected frp Component: Communication channel between frpc and frps, specifically the network transport layer.
  • Risk Severity: Critical (if TLS is not used)
  • Mitigation Strategies:
    • Mandatory TLS Encryption: Always use TLS encryption for all communication between frpc and frps. Configure tls_enable = true in both frps.ini and frpc.ini.
    • Valid Certificates: Use valid TLS certificates issued by a trusted Certificate Authority (CA) or properly configured self-signed certificates with appropriate trust established.
    • Certificate Pinning: Implement certificate pinning (using tls_trusted_ca_file or similar) to prevent attackers from using forged certificates.
    • Strong Cipher Suites: Configure frp to use strong TLS cipher suites and protocols.

Threat: frpc Client Compromise

• Threat: frpc Client Compromise

  • Description: An attacker gains control of a machine running the frpc client. This could occur through malware infection, social engineering, exploiting vulnerabilities in the operating system or other software on the client machine, or physical access.
  • Impact: The attacker gains access to all internal services exposed by that specific frpc client. They could potentially modify the frpc.ini to expose additional services or redirect traffic to malicious destinations. The compromised client could be used as a pivot point to attack other systems on the internal network.
  • Affected frp Component: frpc client, including the frpc.ini configuration file and the running frpc process.
  • Risk Severity: High
  • Mitigation Strategies:
    • Endpoint Protection: Deploy robust endpoint security software (antivirus, EDR, HIDS) on all machines running frpc.
    • Least Privilege: Run frpc with a non-privileged user account. Avoid running it as root or administrator.
    • Configuration File Protection: Protect the frpc.ini file from unauthorized modification using file permissions and integrity monitoring.
    • Regular Security Updates: Keep the operating system and all software on the client machine up-to-date with security patches.
    • User Education: Train users about phishing, social engineering, and safe computing practices.
    • Network Segmentation (Internal): Implement network segmentation within the internal network to limit the blast radius of a compromised client.