# Local Semgrep rules for memory-bank-mcp
#
# This file contains project-specific rules for detecting security issues
# in TypeScript MCP server code.
#
# Run with registry packs:
#   semgrep scan --config p/typescript --config p/security-audit --config p/secrets --config .semgrep.yml
#
# Or local-only:
#   semgrep scan --config .semgrep.yml
rules:
  # =============================================================================
  # PATH TRAVERSAL PREVENTION
  # =============================================================================
  - id: mcp-path-join-user-input
    patterns:
      - pattern-either:
          - pattern: path.join($BASE, $INPUT)
          - pattern: path.resolve($BASE, $INPUT)
      - pattern-not-inside: |
          path.normalize(...)
    message: |
      Path join/resolve detected. Ensure $INPUT is validated for '..' sequences
      to prevent path traversal attacks.
    languages: [typescript, javascript]
    severity: INFO
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: security
      technology: [typescript, mcp]
      cwe: "CWE-22: Improper Limitation of a Pathname to a Restricted Directory"
      references:
        - https://owasp.org/www-community/attacks/Path_Traversal

  # =============================================================================
  # DANGEROUS FUNCTION DETECTION
  # =============================================================================
  - id: mcp-eval-detected
    patterns:
      - pattern-either:
          - pattern: eval(...)
          - pattern: Function(...)
          - pattern: new Function(...)
    message: |
      Dynamic code execution detected. This is high-risk in MCP server code
      where inputs may come from untrusted LLM outputs or user prompts.
    languages: [typescript, javascript]
    severity: ERROR
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: security
      technology: [typescript, mcp]
      cwe: "CWE-94: Improper Control of Generation of Code"
      references:
        - https://cheatsheetseries.owasp.org/cheatsheets/AI_Agent_Security_Cheat_Sheet.html

  - id: mcp-exec-command-injection
    patterns:
      - pattern-either:
          - pattern: exec(...)
          - pattern: execSync(...)
          - pattern: |
              spawn($CMD, { shell: true, ... })
          - pattern: |
              spawnSync($CMD, { shell: true, ... })
    message: |
      Shell command execution detected. In MCP server code, ensure commands
      are not constructed from LLM or user-controlled inputs without validation.
    languages: [typescript, javascript]
    severity: ERROR
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: security
      technology: [typescript, mcp]
      cwe: "CWE-78: Improper Neutralization of Special Elements used in an OS Command"

  # =============================================================================
  # REGEX DENIAL OF SERVICE (ReDoS)
  # =============================================================================
  - id: mcp-regex-from-user-input
    patterns:
      - pattern: new RegExp($VAR, ...)
      - pattern-not: new RegExp("...", ...)
    message: |
      Dynamic regex construction with variable input. Validate the pattern to
      prevent ReDoS attacks from malicious inputs. Consider using safe-regex
      library or pre-validated patterns only.
    languages: [typescript, javascript]
    severity: WARNING
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: security
      technology: [typescript, mcp]
      cwe: "CWE-1333: Inefficient Regular Expression Complexity"
      references:
        - https://owasp.org/www-community/attacks/Regular_expression_Denial_of_Service_-_ReDoS

  # =============================================================================
  # FILE OPERATIONS
  # =============================================================================
  - id: mcp-unsafe-file-write
    patterns:
      - pattern-either:
          - pattern: fs.writeFile($PATH, $DATA, ...)
          - pattern: fs.writeFileSync($PATH, $DATA, ...)
          - pattern: Bun.write($PATH, $DATA, ...)
    message: |
      File write detected. Ensure the path is validated to be within
      an allowed directory before writing.
    languages: [typescript, javascript]
    severity: INFO
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: security
      technology: [typescript, mcp]
      cwe: "CWE-22: Improper Limitation of a Pathname to a Restricted Directory"

  - id: mcp-unsafe-file-read
    patterns:
      - pattern-either:
          - pattern: fs.readFile($PATH, ...)
          - pattern: fs.readFileSync($PATH, ...)
          - pattern: Bun.file($PATH).text()
    message: |
      File read detected. Verify the path is validated to be within
      an allowed directory.
    languages: [typescript, javascript]
    severity: INFO
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: security
      technology: [typescript, mcp]
      cwe: "CWE-22: Improper Limitation of a Pathname to a Restricted Directory"

  # =============================================================================
  # JSON PARSING
  # =============================================================================
  - id: mcp-json-parse-detected
    pattern: JSON.parse($INPUT)
    message: |
      JSON.parse detected. Ensure error handling is in place for malformed input.
    languages: [typescript, javascript]
    severity: INFO
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: reliability
      technology: [typescript, mcp]
      cwe: "CWE-20: Improper Input Validation"

  # =============================================================================
  # SECRETS AND SENSITIVE DATA
  # =============================================================================
  - id: mcp-hardcoded-secrets
    patterns:
      - pattern-either:
          - pattern: |
              $VAR = "sk-..."
          - pattern: |
              $VAR = "ghp_..."
          - pattern: |
              $VAR = "ghs_..."
          - pattern: |
              $VAR = "xoxb-..."
          - pattern: |
              apiKey = "..."
          - pattern: |
              password = "..."
          - pattern: |
              secret = "..."
    message: |
      Potential hardcoded secret detected. Use environment variables or
      secure secret management instead.
    languages: [typescript, javascript]
    severity: ERROR
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: security
      technology: [typescript, mcp]
      cwe: "CWE-798: Use of Hard-coded Credentials"
      references:
        - https://owasp.org/www-community/vulnerabilities/Use_of_hard-coded_password

  - id: mcp-console-log-sensitive
    patterns:
      - pattern-either:
          - pattern: console.log(..., $OBJ.password, ...)
          - pattern: console.log(..., $OBJ.secret, ...)
          - pattern: console.log(..., $OBJ.apiKey, ...)
          - pattern: console.log(..., $OBJ.token, ...)
    message: |
      Potentially logging sensitive data. Remove or redact before logging.
    languages: [typescript, javascript]
    severity: WARNING
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: security
      technology: [typescript, mcp]
      cwe: "CWE-532: Insertion of Sensitive Information into Log File"

  # =============================================================================
  # MCP-SPECIFIC PATTERNS
  # =============================================================================
  - id: mcp-tool-handler-destructuring
    patterns:
      - pattern-inside: |
          case "$TOOL":
            ...
      - pattern: const { $PARAM } = args
    message: |
      MCP tool handler destructures args. Ensure required parameters are
      validated before use to prevent undefined behavior.
    languages: [typescript, javascript]
    severity: INFO
    paths:
      include:
        - src/server/**/*.ts
    metadata:
      category: reliability
      technology: [typescript, mcp]
      cwe: "CWE-20: Improper Input Validation"

  - id: mcp-async-read-write-pattern
    patterns:
      - pattern-inside: |
          async function $FUNC(...) {
            ...
          }
      - pattern: $DATA = await $READ(...)
    message: |
      Async read operation detected. Consider using ETags for optimistic
      concurrency control in read-modify-write patterns.
    languages: [typescript, javascript]
    severity: INFO
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: reliability
      technology: [typescript, mcp]
      cwe: "CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization"

  # =============================================================================
  # ERROR HANDLING
  # =============================================================================
  - id: mcp-catch-log-rethrow
    patterns:
      - pattern: |
          catch ($ERR) {
            console.error(...);
          }
      - pattern-not: |
          catch ($ERR) {
            console.error(...);
            throw ...;
          }
    message: |
      Error caught and logged but not re-thrown. In MCP handlers, consider
      whether the error should propagate to inform the caller.
    languages: [typescript, javascript]
    severity: INFO
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: reliability
      technology: [typescript, mcp]

  - id: mcp-empty-catch
    patterns:
      - pattern-either:
          - pattern: |
              catch ($ERR) { }
          - pattern: |
              catch { }
    message: |
      Empty catch block silently swallows errors. At minimum, log the error.
    languages: [typescript, javascript]
    severity: WARNING
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: reliability
      technology: [typescript, mcp]
      cwe: "CWE-390: Detection of Error Condition Without Action"

  # =============================================================================
  # YAML PARSING (js-yaml specific)
  # =============================================================================
  - id: mcp-yaml-unsafe-load
    patterns:
      - pattern-either:
          - pattern: yaml.load($INPUT)
          - pattern: jsyaml.load($INPUT)
          - pattern: YAML.load($INPUT)
      - pattern-not: |
          yaml.load($INPUT, { schema: ... })
      - pattern-not: yaml.safeLoad(...)
    message: |
      YAML load without explicit schema may execute arbitrary code on crafted
      input. Use yaml.load with { schema: yaml.FAILSAFE_SCHEMA } or yaml.safeLoad.
    languages: [typescript, javascript]
    severity: WARNING
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: security
      technology: [typescript, mcp]
      cwe: "CWE-502: Deserialization of Untrusted Data"
      references:
        - https://www.npmjs.com/package/js-yaml#safeload

  # =============================================================================
  # TYPE SAFETY
  # =============================================================================
  - id: mcp-as-any-cast
    pattern: $EXPR as any
    message: |
      'as any' cast bypasses TypeScript safety. Use specific types or
      'unknown' with type guards instead.
    languages: [typescript]
    severity: INFO
    paths:
      include:
        - src/**/*.ts
      exclude:
        - src/__tests__/**
    metadata:
      category: maintainability
      technology: [typescript, mcp]

  # =============================================================================
  # ASYNC/AWAIT PITFALLS
  # =============================================================================
  - id: mcp-missing-await
    patterns:
      - pattern-inside: |
          async function $FUNC(...) {
            ...
          }
      - pattern: $PROMISE_FUNC(...)
      - pattern-not: await $PROMISE_FUNC(...)
      - pattern-not: return $PROMISE_FUNC(...)
      - metavariable-regex:
          metavariable: $PROMISE_FUNC
          regex: (readFile|writeFile|mkdir|rm|stat|readdir|unlink)
    message: |
      Async file operation without await. The operation may not complete
      before subsequent code runs.
    languages: [typescript, javascript]
    severity: WARNING
    paths:
      include:
        - src/**/*.ts
    metadata:
      category: reliability
      technology: [typescript, mcp]