• Backdoors : An Introduction

    by  • June 6, 2008 • Ethical hacking, General • 0 Comments

    Since the early days of intruders breaking into computers, they have tried

    to develop techniques or backdoors that allow them to get back into the

    system. In this paper, it will be focused on many of the common backdoors

    and possible ways to check for them. Most of focus will be on Unix

    backdoors with some discussion on future Windows NT backdoors. This will

    describe the complexity of the issues in trying to determine the methods

    that intruders use and the basis for administrators understanding on how

    they might be able to stop the intruders from getting back in. When an

    administrator understands how difficult it would be to stop intruder once

    they are in, the appreciation of being proactive to block the intruder from

    ever getting in becomes better understood. This is intended to cover many

    of the popular commonly used backdoors by beginner and advanced intruders.

    This is not intended to cover every possible way to create a backdoor as

    the possibilities are limitless.

    The backdoor for most intruders provide two or three main functions:

    Be able to get back into a machine even if the administrator tries to

    secure it, e.g., changing all the passwords.

    Be able to get back into the machine with the least amount of visibility.

    Most backdoors provide a way to avoid being logged and many times the

    machine can appear to have no one online even while an intruder is using


    Be able to get back into the machine with the least amount of time. Most

    intruders want to easily get back into the machine without having to do all

    the work of exploiting a hole to gain access.

    In some cases, if the intruder may think the administrator may detect any

    installed backdoor, they will resort to using the vulnerability repeatedly

    to get on a machine as the only backdoor. Thus not touching anything that

    may tip off the administrator. Therefore in some cases, the

    vulnerabilities on a machine remain the only unnoticed backdoor.


    Author is a Tech blogger & loves to share his work on web by writing guidelines for Ethical Hacking students & Security professionals. Performing various types of hacking from pen test to smartphone hacking – He enjoys hacking just for personal research purpose. Working with more of 'grey as well as black hat' hackers for learning advanced hacking as well as defending techniques & share them with learners. His prime area of research is Cyber Criminals & currently working on a Video Product Development to teach hacking & Pen Testing for absolute beginners.