Linux TTY Shell Cheat Sheet

Introduction

During a penetration test, when obtaining access to a remote Linux host via a reverse/bind shell, it can be very painful to issue certain commands over it and it is often a much better option to obtain an interactive shell. These are the main reason why this is a good idea:

More shell stability, as things like CTRL+C will no longer close down the connection.
Ability to use up, down, left, and right arrows to navigate through and modify commands.
Ability to use applications or commands that use a login prompt such as Sudo, MySQL, SSH, etc.
Ability to use tab-auto completion in commands.
Ability to view commands, output, and file contents in the same terminal size as the host machine.

This article will list the various commands that can be used to obtain a TTY shell and also how to turn it into a fully interactive shell.

Linux Privilege Escalation – Exploiting Shell Sessions

Introduction

The Linux shell (or terminal) is a program that receives commands from the user, gives them to the operating system to process, and then displays the output on the screen. To make life easier when interacting with a system through a shell, terminal multiplexers can be used; these are software applications that have the ability to combine several separate pseudoterminal-based login sessions inside a single terminal display and they are particularly useful when dealing with multiple programs from a command-line interface and for creating sub-processes that will continue running even when the user is disconnected. Their main purpose is to increase productivity, by allowing users to run multiple programs within a single interface and switch between them seamlessly.

If a terminal multiplexer session is still active as a privileged user (or a different user from the current one), a low-privileged user could be able to attach to it to elevate its access to the user the multiplexer session is running as.

Shell File Transfer Cheat Sheet

Introduction

When performing enumeration steps during a penetration test, there is often the need to transfer files to or from the victim machine, for example to run custom scripts or analyze files further in a controlled environment.

There are different techniques and tools that can be used to transfer files and depending on the target operating system and installed software these may or may not work. The purpose of this cheat sheet is to provide an exhaustive resource for transferring files using command-line interfaces.