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hackeroneAsgerfH1:430831
HistoryOct 30, 2018 - 11:42 a.m.

Node.js third-party modules: Prototype pollution attack in node.extend

2018-10-3011:42:18
asgerf
hackerone.com
68

0.004 Low

EPSS

Percentile

73.4%

I would like to report a prototype pollution vulnerability in node.extend.
It allows an attacker to inject properties on Object.prototype.

Module

module name: node.extendversion:2.0.0npm page: https://www.npmjs.com/package/node.extend

Module Description

A port of jQuery.extend that actually works on node.js

Module Stats

267,701 downloads in the last week

Vulnerability

Vulnerability Description

This is a variant of this vulnerability:
https://hackerone.com/reports/310443

node.extend can be tricked into adding or modifying properties of the Object prototype. These properties will be present on all objects.

Steps To Reproduce:

Craft an object of form {__proto__: {...}} and send it to node.extend:

let extend = require('node.extend');
extend(true, {}, JSON.parse('{"__proto__": {"isAdmin": true}}'));
console.log({}.isAdmin); // true

Wrap up

  • I contacted the maintainer to let them know: [N]
  • I opened an issue in the related repository: [N]

Impact

Denial of service, possibly more depending on the application.
See https://hackerone.com/reports/310443