What is a backdoor: how unknown backdoors give an ousider COMPLETE access to your files and Internet activity

What they are, how they are used to invade a computer network or a personal computer.

Review: In the last article, Firewalls and Backdoors, we discussed how a firewall is acts to defend a computer from invasion. In this article we talk about how that defense can be breached and what it means to you.

A proxy server is a method by which computers talk to each other. An open proxy is a backdoor that has been opened in a computer network (either by a friendly or unfriendly method), meaning that the network's Internet access can be used by authorized personnel within the network or, if the backdoor is not well-protected or is unknown, by malicious access from anywhere in the world outside the network. Unknown backdoors can be installed on a personal computer, desktop or laptop.

The purpose of a backdoor is to get around the security measures installed to protect a computer system and allow access into the system from the outside. If the backdoor was opened by a piece of spyware, then that spyware was programmed to sniff out standard security programming and disable a part of the security program that recognizes and blocks an unauthorized attempt to access that computer and its network. If the backdoor was opened by a live person sitting at the computer, then the recognition pattern was disabled manually.

Malicious programs that open backdoors can be found in emails, ad banners, web sites, and downloads, sometimes without the knowledge of the website or download owner, or without the knowledge of the email author. Trojan horses are a popular method of opening backdoors.

In the past, backdoors were only a problem for IT (Information Technology) Managers in large corporations, universities, and government facilities where sometimes hundreds of computers are linked together under one roof or between geographically separated offices.

Today families and small businesses network their computers, as do libraries, clinics, rehab hospices, retirement homes, and local law enforcement departments. Even isolated computers are susceptible to invasion through the covert installation of malicious programs that open a passage through the computer's firewall.

There are programs that spend 24 hours a day surfing the Web in search of unprotected and unknown backdoors. They run around "pinging" IP's until they find one that sends back a signal indicating that access can be granted. A program such as CallerIP scans all the ports (where your modem or cable or telephone is plugged in) on your system and alerts you to any malicious backdoors that can provide unauthorized access to your computer.

Log on to your computer and operate it from a remote location.
Access your email list and/or use your Internet connection. This is called SMTP hijacking and is hugely popular with email scammers such as Nigerian con artists and email spammers who send out worms, viruses, unsolicited advertising, etc. When you track the email path, it shows that the letter was sent from a corporation in Walla Walla, Washington or from a college in Texas instead of from it's true origin.
Find files/documents that are not protected and destroy, copy, email, and alter them. That's why it's so important to install software like Folder Access.
Run programs, alter or delete programs.
Install hidden programs to watch what you do with your computer and where you go on the Internet. Spyware can keep a record of every web site you visit, every email you write, every chat in a chat room (public or private), every Private Message, every online purchase you make, every bit of online banking you do. Keyloggers can record every keystroke you make, including passwords, user names, identification numbers, bank account numbers, and credit card numbers. To prevent such attacks, you need to install SecureClean to uncover existing malicious programs and prevent others from being installed.
Move from computer to computer within a network, access servers, steal and/or alter passwords, sensitive information, and personnel information.
Insert worms, viruses, and spyware into the computer owner or network owner's email programs, web sites or pages, ad banners, and downloads.
Crash a single computer or move through a network crashing one computer after the other. SOS Data Protection & Recovery Software is a real life-saver in that situation.
Send hundreds of requests to a network server that the server can't respond to (this is can cause a corporate web site to crash if it's the server where the site is stored); send hundreds of large emails to employees causing the email program to overload.
Change the path information takes through a network by inserting redirects that can cause the information to loop endlessly until the information transfer is rejected, or the altered path may send the information to a competitor.
The above malice list covers the highlights. Once malicious access has occurred to an individual computer or a network, so much damage is possible that recovery can be prohibitively expensive and public embarrassment overwhelming.