Attack Surface Analysis for zeromicro/go-zero

Attack Surface: 1. Input Validation Bypass at API Gateway

Description: Insufficient input validation within Go-Zero API Gateway handlers allows malicious requests to bypass initial checks and reach backend services.
Go-Zero Contribution: Go-Zero's rest package provides the framework for building API Gateways. If input validation is not properly implemented in rest.Handler functions or custom middleware, it directly contributes to this vulnerability.
Example: A Go-Zero API endpoint defined using rest.Handler expects an integer user_id path parameter but the handler code does not validate if the provided value is indeed an integer. An attacker can send a request with a non-integer value or a malicious payload as user_id, potentially causing errors or exploiting vulnerabilities in backend services that assume integer input.
Impact: Backend services become vulnerable to attacks that should be filtered at the gateway. This can lead to data breaches, service disruption, or unauthorized access to backend functionalities.
Risk Severity: High
Mitigation Strategies:
- Utilize Go-Zero's Request Validation: Leverage Go-Zero's built-in request validation features within rest.Handler functions. Define request structs with validation tags (e.g., using binding tags) to automatically validate incoming requests based on defined rules.
- Implement Custom Validation Middleware: Create custom middleware using Go-Zero's middleware capabilities to enforce more complex or application-specific input validation logic before requests reach handlers.
- Sanitize Inputs in Handlers: Within rest.Handler functions, explicitly validate and sanitize all input parameters extracted from requests before processing them further or passing them to backend services.

Attack Surface: 2. Authentication Bypass in API Gateway

Description: Vulnerabilities in the authentication and authorization implementation within the Go-Zero API Gateway allow unauthorized users to bypass security checks and access protected resources.
Go-Zero Contribution: Go-Zero's rest package provides middleware functionality that is commonly used to implement authentication and authorization in API Gateways. Flaws in custom middleware or misconfiguration of authentication logic within rest handlers directly create this attack surface.
Example: A Go-Zero API Gateway uses custom middleware for JWT authentication. If this middleware incorrectly verifies JWT signatures, fails to handle token expiration properly, or has logic flaws allowing token forgery, an attacker can bypass authentication and access protected API endpoints without valid credentials.
Impact: Unauthorized access to sensitive data and functionalities protected by the API Gateway. This can lead to data breaches, data manipulation, privilege escalation, and complete compromise of protected resources.
Risk Severity: Critical
Mitigation Strategies:
- Leverage Go-Zero Middleware for Authentication: Utilize Go-Zero's middleware feature to encapsulate authentication and authorization logic. This promotes code reusability and separation of concerns.
- Use Established Authentication Libraries: Integrate well-vetted and secure Go libraries for authentication mechanisms like JWT, OAuth 2.0 within Go-Zero middleware. Avoid implementing custom, potentially flawed authentication algorithms.
- Thoroughly Test Authentication Middleware: Rigorously test custom authentication middleware and configurations, including unit tests and integration tests, to identify and fix potential bypass vulnerabilities. Pay special attention to edge cases, token handling, and error conditions.
- Regular Security Audits of Authentication Logic: Conduct periodic security audits and code reviews specifically focused on the authentication and authorization implementations within the Go-Zero API Gateway.

Attack Surface: 3. Deserialization Vulnerabilities in RPC Communication

Description: Exploiting vulnerabilities during the deserialization of data in Go-Zero RPC communication can lead to critical issues like remote code execution on microservices.
Go-Zero Contribution: Go-Zero's rpc package handles inter-service communication and relies on serialization/deserialization of data. If insecure serialization libraries are used or if custom serialization logic is flawed within Go-Zero RPC services, it directly introduces this high-risk attack surface.
Example: A Go-Zero RPC service uses protobuf for communication. If a vulnerability exists in the version of the protobuf library used for deserializing RPC requests, an attacker can craft a malicious RPC request with a specially crafted payload. When the receiving Go-Zero service deserializes this payload using the vulnerable protobuf library, it could lead to remote code execution on the service.
Impact: Remote code execution on backend microservices. This is a critical vulnerability that can allow attackers to gain complete control of compromised services, leading to data breaches, service disruption, and lateral movement within the system.
Risk Severity: Critical
Mitigation Strategies:
- Use Secure and Up-to-Date Serialization Libraries: Choose well-established and actively maintained serialization libraries for Go-Zero RPC communication. Regularly update these libraries to the latest versions to patch known deserialization vulnerabilities.
- Minimize Custom Serialization Logic: Avoid implementing custom serialization logic as much as possible. Rely on well-vetted, standard serialization formats and libraries provided by Go.
- Input Validation in RPC Handlers: Implement robust input validation and sanitization within Go-Zero RPC handlers. Treat all data received via RPC as potentially untrusted and validate it before processing, even if serialization is considered secure. This adds a defense-in-depth layer.
- Transport Layer Security (TLS) for RPC: Enforce TLS encryption for all Go-Zero RPC communication to protect against man-in-the-middle attacks and ensure confidentiality and integrity of data during transmission. Configure Go-Zero RPC services to use secure transport options like gRPC with TLS.