javascript.express.security.express-vm-injection.express-vm-code-injection

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LGPL Commons Clause
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Make sure that unverified user data can not reach vm instance.

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Defintion

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rules:
  - id: express-vm-code-injection
    message: |
      Make sure that unverified user data can not reach vm instance.
    severity: ERROR
    languages:
      - javascript
      - typescript
    metadata:
      owasp: "A1: Injection"
      cwe: "CWE-94: Improper Control of Generation of Code (Code Injection)"
      category: security
      technology:
        - express
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]
    patterns:
      - pattern-inside: |
          $VM = require('vm');
          ...
      - pattern-either:
          - pattern-inside: function ... ($REQ, $RES) {...}
          - pattern-inside: function ... ($REQ, $RES, $NEXT) {...}
          - pattern-inside: $APP.get(..., function $FUNC($REQ, $RES) {...})
          - pattern-inside: $APP.post(..., function $FUNC($REQ, $RES) {...})
          - pattern-inside: $APP.put(..., function $FUNC($REQ, $RES) {...})
          - pattern-inside: $APP.head(..., function $FUNC($REQ, $RES) {...})
          - pattern-inside: $APP.delete(..., function $FUNC($REQ, $RES) {...})
          - pattern-inside: $APP.options(..., function $FUNC($REQ, $RES) {...})
      - pattern-either:
          - pattern: $VM.runInContext(<... $REQ.$QUERY.$FOO ...>,...)
          - pattern: $VM.runInContext(<... $REQ.$BODY ...>,...)
          - pattern: |
              $INPUT = <... $REQ.$QUERY.$FOO ...>;
              ...
              $VM.runInContext($INPUT,...);
          - pattern: |
              $INPUT = <... $REQ.$BODY ...>;
              ...
              $VM.runInContext($INPUT,...);
          - pattern: $VM.runInNewContext(<... $REQ.$QUERY.$FOO ...>,...)
          - pattern: $VM.runInNewContext(<... $REQ.$BODY ...>,...)
          - pattern: |
              $INPUT = <... $REQ.$QUERY.$FOO ...>;
              ...
              $VM.runInNewContext($INPUT,...);
          - pattern: |
              $INPUT = <... $REQ.$BODY ...>;
              ...
              $VM.runInNewContext($INPUT,...);
          - pattern: $VM.runInThisContext(<... $REQ.$QUERY.$FOO ...>,...)
          - pattern: $VM.runInThisContext(<... $REQ.$BODY ...>,...)
          - pattern: |
              $INPUT = <... $REQ.$QUERY.$FOO ...>;
              ...
              $VM.runInThisContext($INPUT,...);
          - pattern: |
              $INPUT = <... $REQ.$BODY ...>;
              ...
              $VM.runInThisContext($INPUT,...);
          - pattern: $VM.compileFunction(<... $REQ.$QUERY.$FOO ...>,...)
          - pattern: $VM.compileFunction(<... $REQ.$BODY ...>,...)
          - pattern: |
              $INPUT = <... $REQ.$QUERY.$FOO ...>;
              ...
              $VM.compileFunction($INPUT,...);
          - pattern: |
              $INPUT = <... $REQ.$BODY ...>;
              ...
              $VM.compileFunction($INPUT,...);
          - pattern: new $VM.Script(<... $REQ.$QUERY.$FOO ...>,...)
          - pattern: new $VM.Script(<... $REQ.$BODY ...>,...)
          - pattern: |
              $INPUT = <... $REQ.$QUERY.$FOO ...>;
              ...
              new $VM.Script($INPUT,...);
          - pattern: |
              $INPUT = <... $REQ.$BODY ...>;
              ...
              new $VM.Script($INPUT,...);

Examples

express-vm-injection.js

const vm = require('vm')

let ctrl1 = function test1(req,res) {
    // ruleid:express-vm-runincontext-context-injection
    var input = req.query.something || ''
    var sandbox = {
        foo: input
    }
    vm.createContext(sandbox)
    vm.runInContext('safeEval(orderLinesData)', sandbox, { timeout: 2000 })
    res.send('hello world')
}
app.get('/', ctrl1)

app.get('/', (req,res) => {
    // ruleid:express-vm-runincontext-context-injection
    var sandbox = {
        foo: req.query.userInput
    }
    vm.createContext(sandbox)
    vm.runInContext('safeEval(orderLinesData)', sandbox, { timeout: 2000 })
    res.send('hello world')
})

// ok:express-vm-runincontext-context-injection
function testOk1(userInput) {
    var sandbox = {
        foo: 1
    }
    vm.createContext(sandbox)
    vm.runInContext('safeEval(orderLinesData)', sandbox, { timeout: 2000 })
}

var ctrl2 = null;
ctrl2 = function test2(req,res) {
    // ruleid:express-vm-runinnewcontext-context-injection
    var input = req.query.something || ''
    var sandbox = {
        foo: input
    }
    vm.runInNewContext('safeEval(orderLinesData)', sandbox, { timeout: 2000 })
    res.send('hello world')
}
app.get('/', ctrl2)


app.get('/', function (req,res) {
    // ruleid:express-vm-runinnewcontext-context-injection
    var sandbox = {
        foo: req.query.userInput
    }
    vm.runInNewContext('safeEval(orderLinesData)', sandbox, { timeout: 2000 })
    res.send('hello world')
})

// ok:express-vm-runinnewcontext-context-injection
app.get('/', function testOk1(userInput) {
    var sandbox = {
        foo: 1
    }
    vm.runInNewContext('safeEval(orderLinesData)', sandbox, { timeout: 2000 })
    res.send('hello world')
})

app.get('/', function(req,res) {
    // ruleid:express-vm-code-injection
    const code = `
        var x = ${req.query.userInput};
    `
    vm.runInThisContext(code)
    res.send('hello world')
})

// ok:express-vm-code-injection
app.get('/', function okTest3(req,res) {
    const code = `
        var x = 1;
    `
    vm.runInThisContext(code)
    res.send('hello world')
})

app.get('/', function test4(req,res) {
    const parsingContext = vm.createContext({name: 'world'})
    // ruleid:express-vm-code-injection
    const code = `return 'hello ' + ${req.query.userInput}`
    let fn = vm.compileFunction(code, [], { parsingContext })
    res.send('hello world')
})

// ok:express-vm-code-injection
app.get('/', function okTest4(req,res) {
    const parsingContext = vm.createContext({name: 'world'})
    const code = `return 'hello ' + name`
    const fn = vm.compileFunction(code, [], { parsingContext })
})

app.get('/', (req,res) => {
    // ruleid:express-vm-compilefunction-context-injection
    const context = vm.createContext({name: req.query.userInput})
    let code = `return 'hello ' name`
    const fn = vm.compileFunction(code, [], { parsingContext: context })
    res.send('hello world')
})

// ok:express-vm-compilefunction-context-injection
app.get('/', function okTest5(req, res) {
    const parsingContext = vm.createContext({name: 'world'})
    const code = `return 'hello ' + name`
    const fn = vm.compileFunction(code, [], { parsingContext })
    res.send('hello world')
})

app.get('/', function (req,res) {
    // ruleid:express-vm-code-injection
    const script = new vm.Script(`
        function add(a, b) {
          return a + ${req.query.userInput};
        }

        const x = add(1, 2);
    `);

    script.runInThisContext();
    res.send('hello world')
})

//ok:express-vm-code-injection
app.get('/', function okTest6(req, res) {
    const script = new vm.Script(`
        function add(a, b) {
          return a + b;
        }

        const x = add(1, 2);
    `);

    script.runInThisContext();
    res.send('hello world')
})