mcp-server-semgrep/semgrep-rules/javascript/express/security/express-insecure-template-usage.yaml

MCP Server for Semgrep Integration - static code analysis with AI

rules:
- id: express-insecure-template-usage
  message: User data from `$REQ` is being compiled into the template, which can lead to a Server Side
    Template Injection (SSTI) vulnerability.
  options:
    interfile: true
  metadata:
    interfile: true
    category: security
    cwe:
    - 'CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine'
    owasp:
    - A03:2021 - Injection
    - A01:2017 - Injection
    references:
    - https://cheatsheetseries.owasp.org/cheatsheets/Injection_Prevention_Cheat_Sheet.html
    technology:
    - javascript
    - typescript
    - express
    - pug
    - jade
    - dot
    - ejs
    - nunjucks
    - lodash
    - handlbars
    - mustache
    - hogan.js
    - eta
    - squirrelly
    source_rule_url:
    - https://github.com/github/codeql/blob/2ba2642c7ab29b9eedef33bcc2b8cd1d203d0c10/javascript/ql/test/query-tests/Security/CWE-094/CodeInjection/template-sinks.js
    subcategory:
    - vuln
    likelihood: MEDIUM
    impact: MEDIUM
    confidence: MEDIUM
  languages:
  - javascript
  - typescript
  severity: WARNING
  mode: taint
  pattern-propagators:
  - pattern: $MODEL.$FIND($E).then((...,$S,...)=>{...})
    from: $E
    to: $S
  pattern-sources:
  - patterns:
    - pattern-either:
      - pattern-inside: function ... ($REQ, $RES) {...}
      - pattern-inside: function ... ($REQ, $RES, $NEXT) {...}
      - patterns:
        - pattern-either:
          - pattern-inside: $APP.$METHOD(..., function $FUNC($REQ, $RES) {...})
          - pattern-inside: $APP.$METHOD(..., function $FUNC($REQ, $RES, $NEXT) {...})
        - metavariable-regex:
            metavariable: $METHOD
            regex: ^(get|post|put|head|delete|options)$
    - pattern-either:
      - pattern: $REQ.query
      - pattern: $REQ.body
      - pattern: $REQ.params
      - pattern: $REQ.cookies
      - pattern: $REQ.headers
  - patterns:
    - pattern-either:
      - pattern-inside: |
          ({ $REQ }: Request,$RES: Response, $NEXT: NextFunction) =>
          {...}
      - pattern-inside: |
          ({ $REQ }: Request,$RES: Response) => {...}
    - focus-metavariable: $REQ
    - pattern-either:
      - pattern: params
      - pattern: query
      - pattern: cookies
      - pattern: headers
      - pattern: body
  pattern-sinks:
  - pattern-either:
    - patterns:
      - pattern-either:
        - pattern-inside: |
            $PUG = require('pug')
            ...
        - pattern-inside: |
            import * as $PUG from 'pug'
            ...
        - pattern-inside: |
            $PUG = require('jade')
            ...
        - pattern-inside: |
            import * as $PUG from 'jade'
            ...
      - pattern-either:
        - pattern: $PUG.compile(...)
        - pattern: $PUG.compileClient(...)
        - pattern: $PUG.compileClientWithDependenciesTracked(...)
        - pattern: $PUG.render(...)
    - patterns:
      - pattern-either:
        - pattern-inside: |
            $PUG = require('dot')
            ...
        - pattern-inside: |
            import * as $PUG from 'dot'
            ...
      - pattern-either:
        - pattern: $PUG.template(...)
        - pattern: $PUG.compile(...)
    - patterns:
      - pattern-either:
        - pattern-inside: |
            $PUG = require('ejs')
            ...
        - pattern-inside: |
            import * as $PUG from 'ejs'
            ...
      - pattern-either:
        - pattern: $PUG.render(...)
    - patterns:
      - pattern-either:
        - pattern-inside: |
            $PUG = require('nunjucks')
            ...
        - pattern-inside: |
            import * as $PUG from 'nunjucks'
            ...
      - pattern-either:
        - pattern: $PUG.renderString(...)
    - patterns:
      - pattern-either:
        - pattern-inside: |
            $PUG = require('lodash')
            ...
        - pattern-inside: |
            import * as $PUG from 'lodash'
            ...
      - pattern-either:
        - pattern: $PUG.template(...)
    - patterns:
      - pattern-either:
        - pattern-inside: |
            $PUG = require('mustache')
            ...
        - pattern-inside: |
            import * as $PUG from 'mustache'
            ...
        - pattern-inside: |
            $PUG = require('eta')
            ...
        - pattern-inside: |
            import * as $PUG from 'eta'
            ...
        - pattern-inside: |
            $PUG = require('squirrelly')
            ...
        - pattern-inside: |
            import * as $PUG from 'squirrelly'
            ...
      - pattern-either:
        - pattern: $PUG.render(...)
    - patterns:
      - pattern-either:
        - pattern-inside: |
            $PUG = require('hogan.js')
            ...
        - pattern-inside: |
            import * as $PUG from 'hogan.js'
            ...
        - pattern-inside: |
            $PUG = require('handlebars')
            ...
        - pattern-inside: |
            import * as $PUG from 'handlebars'
            ...
      - pattern-either:
        - pattern: $PUG.compile(...)