🧨Exploiting Microsoft IIS WebDAV

What is Microsoft IIS ?

• IIS (Internet Information Services) is a proprietary extensible web server software developed by Microsoft for use with the Windows NT family.

• It can be used to host websites/web apps and provides administrators with a robust GUI for managing websites.

• IIS can be used to host both static and dynamic web pages developed in ASP.NET and PHP.

• Typically configured to run on ports 80/443.

• Supported executable file extensions:

  • .asp

  • .aspx

  • .config

  • .php

What is WebDAV?

• WebDAV (Web-based Distributed Authoring and Versioning) is a set of extensions to the HTTP protocol which allow users to collaboratively edit and manage files on remote web servers.

• WebDAV essentially enables a web server to function as a file server for collaborative authoring.

• WebDAV runs on top Microsoft IIS on ports 80/443.

• In order to connect to a WebDAV server, you will need to provide legitimate credentials. This is because WebDAV implements authentication in the form of a username and password.

WebDAV Exploitation

• The first step of the exploitation process will involve identifying whether WebDAV has been configured to run on the IIS web server.

• We can perform a brute-force attack on the WebDAV server in order to identify legitimate credentials that we can use for authentication.

• After obtaining legitimate credentials, we can authenticate with the WebDAV server and upload a malicious .asp payload that can be used to execute arbitrary commands or obtain a reverse shell on the target.

Tools for Exploitation

• davtest- Used to scan, authenticate and exploit a WebDAV server.
• cadaver - Cadaver supports file upload, download, on-screen display, in-place editing, namespace operations (move/copy), collection creation and deletion, property manipulation, and resource locking on WebDAV servers.

Attack Flow for the Microsoft IIS WebDAV Server

1. Identify the Target Using Nmap

Objective: Determine if the target web application is running Microsoft IIS WebDAV.

Command:

nmap -sC --script=http-enum <target>

Explanation:

• -sC: Use default scripts.

• --script=http-enum: Specifically use the HTTP enumeration script to gather detailed information about the web server and its directories.

2. Brute Force Authentication Using Hydra

Objective: Perform a brute force attack on the /webdav/ folder to gain authentication credentials.

Command:

hydra -l <user> -P <password_list> <target> http-get /webdav/

Explanation:

• -l: Specifies the username.

• -P: Specifies the password list.

• http-get: Specifies the HTTP method and path to target.

3. Validate Upload Capabilities with Davtest

Objective: Confirm which file extensions can be uploaded and executed on the WebDAV server.

Command:

davtest -auth <user>:<pass> -url http://<target>/webdav

Explanation:

• -auth: Specifies the authentication credentials.

• -url: Specifies the URL of the WebDAV directory.

4. Upload a Shell Using Cadaver

Objective: Use Cadaver to upload a web shell to the server.

Command:

cadaver http://<target>/webdav

Procedure:

1. Run the command to start Cadaver.

2. When prompted, enter the username and password obtained from the brute force attack.

3. At the dav:/webdav/> prompt, use the following command to upload the shell:

   put /usr/share/webshells/asp/webshell.asp

Explanation:

• cadaver: Command-line WebDAV client.

• put: Uploads the specified file to the WebDAV directory.

5. Access the Web Shell

Objective: Gain a GUI-based shell access to the server.

Steps:

1. Navigate to the uploaded shell in your browser:

   http://<target>/webdav/webshell.asp

2. Use the web shell interface to execute commands on the server.

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Hacker's Mantra:Should we fear hackers? Intention is at the heart of this discussion. - Kevin Mitnick