How to clean up files using FileDropper

In some exploitation scenarios such as local privilege escalation, command execution, write privilege attacks, SQL Injections, etc, it is very likely that you have to upload one or more malicious files in order to gain control of the target machine. Well, a smart attacker shouldn't leave anything behind, so if a module needs to drop something onto the file system, it's important to remove it right after the purpose is served. And that is why we created the FileDropper mixin.

Examples

The FileDropper mixin is a file manager that allows you keep track of files, and then delete them when a session is created. To use it, first include the mixin like so:

include Msf::Exploit::FileDropper

Next, tell the FileDropper mixin where the file is going to be after a session is created by using the register_file_for_cleanup method. Each file name should either be a full path, or relative to the current working directory of the session. For example, if I want to upload a payload to the target machine's remote path: C:\Windows\System32\payload.exe, then my statement can be:

register_file_for_cleanup("C:\\Windows\\System32\\payload.exe")

If my session's current directory is already in C:\Windows\System32\, then I can simply do:

register_file_for_cleanup("payload.exe")

If you wish to register multiple files, you can also provide the file names as arguments:

register_file_for_cleanup("file_1.vbs", "file_2.exe", "file_1.conf")

Note that if your exploit module uses on_new_session, you are actually overriding FileDropper's on_new_session.

Reference

https://github.com/rapid7/metasploit-framework/blob/master/lib/msf/core/exploit/file_dropper.rb