ScreengrabHow do Trojan viruses infect your computer? Where does spam come from? How do hackers gain control over your computer?
Often times, the answer is via botnet.
A botnet is nothing more than a small program that people install (usually without realising it) that “phones home” to another computer and carries out whatever instructions it’s given.
On it’s own, a single infected computer isn’t much to write home about. But when you’re talking about 100 or 1,000 (and often times even more) computers, a hacker has a lot of computing power at his disposal.
One of the most popular means of gaining access to a computer is to hide a Trojan in an email attachment joins the botnet upon installation. This happens without the user’s knowledge or consent. From here, the botnet owner can deploy commands to his collection of compromised computers.
Using readily-available software that's nothing more than a search away, people who mean you harm can get a customised Zeus botnet up and running in minutes. At this point, they distribute it, most likely via email.
They'll employ a little bit of human engineering to get you to install a program that connects back to a server that they control. At this point, they are able to send commands to your computer.
The Botting Network is one of the largest of these. People who run their own botnets (whether for legitimate or illegitimate purposes) will come together to trade tips and thoughts on maintaining a botnet.
You can get your own botnet off to a start by buying 100 infected computers for somewhere in the neighbourhood of $10.
There are a number of ways to put a botnet to work to reap financial reward. You can get infected computers working together to mine bitcoins at an incredible rate. If you get referral kickback from certain websites, you can have the botnet access those sites through your referral link. If you get income from people clicking on Google AdSense or other banner ads, you can have these computers click on them for you.
Because each of these computers has its own IP address and can be easily distributed across a huge distance, it becomes incredibly difficult to detect.
By getting each infected computer to repeatedly access a website, a botnet can take that site out of commission in what is called a 'denial of service' attack. Basically it clogs the internet traffic to that site so severely that no one can get through.
Spam, the scourge of email, often comes from botnets. By distributing the workload of sending so many emails between a number of computers, it becomes a trivial effort to send hundreds of thousands of messages.
If you want to get even more nefarious, you can capture and record people's keystrokes on their computers. This gets you access to all kinds of sensitive data -- passwords, bank account numbers, private communications, and the like.
If you're especially invested in the outcome of an internet poll, your botnet can go in and vote en masse for your desired outcome. This is especially useful for contests or polls with any real-world outcome.
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