# NoSQL Injection Detection
# Detects MongoDB $where operator usage, which executes arbitrary JS server-side (S5147).
id: ts-nosql-injection
name: NoSQL Injection
severity: error
category: security
defect_class: injection
inline_tier: blocking
language: typescript

message: "NoSQL injection — $where executes JavaScript server-side and must never be used with user input"

description: |
  The MongoDB $where operator runs a JavaScript expression on the server.
  Any use of $where is dangerous: with dynamic values it is directly
  injectable; even with static strings it exposes a JS execution surface.

  Use field equality operators instead — they are safe and faster.

  ❌ NEVER:
  db.users.find({ $where: `this.name === '${name}'` })
  collection.find({ "$where": "this.credits > 0 && code == '" + input + "'" })

  ✅ SAFE:
  db.users.find({ name: name })
  collection.find({ credits: { $gt: 0 }, code: input })

query: |
  (pair
    key: [(property_identifier) (string)] @KEY
    (#match? @KEY "\\$where"))

metavars:
  - KEY

has_fix: false

tags:
  - typescript
  - javascript
  - security
  - nosql
  - injection
  - cwe-943
  - owasp-a03

examples:
  bad: |
    db.users.find({ $where: `this.password === '${userPassword}'` })
    collection.find({ "$where": "this.credits > 0 && this.code == '" + input + "'" })

  good: |
    db.users.find({ password: userPassword })
    collection.find({ credits: { $gt: 0 }, code: input })