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Threat Model Analysis for cloudwego/kitex

Threat: Service Spoofing via Service Discovery Manipulation

  • Description: An attacker compromises the service discovery mechanism used by Kitex (e.g., Consul, etcd, Kubernetes API, or a custom discovery.Resolver implementation) to register a malicious service instance. Kitex's client.Client, when configured to use service discovery, will resolve the malicious service's address and connect to it, believing it to be the legitimate service.
    • Impact: Loss of confidentiality (data exposure), integrity (data modification), and availability (service disruption). The attacker can intercept, modify, or drop requests intended for the legitimate service.
    • Kitex Component Affected: client.Client (when using service discovery), pkg/discovery (the service discovery interface and implementations), and any custom discovery.Resolver implementations.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Secure Service Discovery: Use a secure and trusted service discovery mechanism. Harden the service discovery infrastructure against unauthorized access and modification. Implement strong authentication and authorization for service registration and discovery.
      • mTLS: Enforce mutual TLS (mTLS) between all Kitex services. This ensures that both the Kitex client (client.Client) and server (server.Server) authenticate each other using certificates. Configure Kitex's WithMutualTLS client option and WithMutualTLS server option.
      • Service Identity Validation: Implement additional validation within a custom discovery.Resolver to verify the service identity retrieved from the discovery mechanism. Check the certificate's Subject Alternative Name (SAN) against a known list of valid service identities.

Threat: Message Tampering via Man-in-the-Middle (MITM) Attack (Without TLS)

  • Description: If TLS is not enabled or is misconfigured, an attacker can intercept the network traffic between Kitex services. Kitex's transport.ClientTransport and transport.ServerTransport handle the underlying network communication. Without encryption, the attacker can modify requests or responses in transit, altering data or injecting malicious payloads. This directly impacts the Kitex transport layer.
    • Impact: Loss of data integrity. The attacker can modify data, leading to incorrect application behavior, financial losses, or data corruption.
    • Kitex Component Affected: transport.ClientTransport and transport.ServerTransport (the underlying network transport layer), and the specific protocol implementation used (e.g., transport/thrift, transport/grpc).
    • Risk Severity: High
    • Mitigation Strategies:
      • TLS Encryption: Enforce TLS encryption for all communication between Kitex services. Use Kitex's WithTransportProtocol client option and WithTransportProtocol server option to specify transport.TTHeaderFramed or transport.GRPC (which inherently uses TLS). Do not use transport.Framed or transport.Buffered without TLS.
      • Strong TLS Configuration: Use a robust TLS configuration, including strong ciphers and up-to-date TLS versions (TLS 1.3 is preferred). Avoid deprecated protocols and ciphers. Configure this using Kitex's TLS options.

Threat: Denial of Service via Connection Exhaustion (Kitex Server)

  • Description: An attacker opens a large number of connections to a Kitex server.Server but does not send any requests (or sends them very slowly). This exhausts the server's resources (file descriptors, memory), preventing legitimate Kitex clients from connecting. This directly targets the Kitex server's connection handling.
    • Impact: Service unavailability. Legitimate Kitex clients cannot access the service.
    • Kitex Component Affected: server.Server, transport.ServerTransport, and the underlying network stack.
    • Risk Severity: High
    • Mitigation Strategies:
      • Connection Timeouts: Configure appropriate connection timeouts on the Kitex server using WithReadTimeout and WithConnectTimeout server options. This will close idle connections after a specified period, mitigating slowloris attacks.
      • Rate Limiting (Kitex Middleware): Implement rate limiting at the Kitex service level using Kitex's limit.Option and a suitable limit.Limiter implementation (e.g., limit.NewConcurrencyLimiter). This limits the number of connections or requests from a single client.

Threat: Denial of Service via Request Flooding (Kitex Server)

  • Description: An attacker sends a large volume of requests to a Kitex server.Server, overwhelming its processing capacity and causing it to become unresponsive to legitimate Kitex clients. This directly targets the Kitex server's request handling.
    • Impact: Service unavailability. Legitimate Kitex clients cannot access the service.
    • Kitex Component Affected: server.Server, transport.ServerTransport, and the service handler logic (although the handler is invoked by Kitex).
    • Risk Severity: High
    • Mitigation Strategies:
      • Rate Limiting (Kitex Middleware): Implement rate limiting at the Kitex service level, as described above, using Kitex's limit.Option and a suitable limit.Limiter. This is the primary defense.
      • Circuit Breaking (Kitex Middleware): Use Kitex's circuit breaking functionality (circuitbreak.Options) to prevent cascading failures. If a service becomes overloaded, the circuit breaker will temporarily stop sending requests to it, allowing it to recover.

Threat: Codec Vulnerability Exploitation (Kitex Codec)

  • Description: An attacker exploits a vulnerability in the serialization/deserialization codec used by Kitex (e.g., Thrift, Protobuf, JSON). This vulnerability resides within Kitex's pkg/codec and the specific codec implementation (e.g., pkg/codec/thrift, pkg/codec/protobuf, pkg/codec/json). Successful exploitation could lead to remote code execution or denial of service.
    • Impact: Remote code execution (Critical), denial of service (High), or data corruption, depending on the specific vulnerability.
    • Kitex Component Affected: pkg/codec and the specific codec implementation used.
    • Risk Severity: Critical (if RCE is possible), High (otherwise)
    • Mitigation Strategies:
      • Keep Codecs Updated: Keep the codec libraries (e.g., Thrift, Protobuf) used by Kitex up to date. Regularly apply security patches. This is crucial, as codec vulnerabilities are frequently discovered. Ensure Kitex itself is updated to use patched versions of these libraries.
      • Input Validation (Pre-Codec): Implement robust input validation before the data reaches Kitex's deserialization (pkg/codec) logic. This can mitigate some codec vulnerabilities by preventing malformed data from being processed.

Threat: Uncontrolled Recursion in Deserialization (Kitex Codec)

  • Description: An attacker crafts a malicious message with deeply nested structures. When Kitex's pkg/codec attempts to deserialize this message, it causes excessive memory allocation or a stack overflow, leading to a denial-of-service. This is a vulnerability within Kitex's codec handling.
    • Impact: Denial of service due to resource exhaustion (memory or stack).
    • Kitex Component Affected: pkg/codec and the specific codec implementation (e.g., pkg/codec/thrift, pkg/codec/protobuf).
    • Risk Severity: High
    • Mitigation Strategies:
      • Codec Configuration: Some codecs may offer configuration options to limit recursion depth. Check the documentation for the specific codec being used (Thrift, Protobuf, etc.) and see if Kitex exposes these options.
      • Input Validation (Pre-Codec): Validate the structure of the input data before it reaches Kitex's deserialization logic to ensure it conforms to expected limits on nesting depth. This is the most reliable mitigation.