Bots & Botnets

From Computing and Software Wiki

A Botnet is a collection of infected computers that can be used to attack organizations and distribute illegal information due to the sheer number of computers that is contained within them. Botnets are hard to prevent as the computers that become bots usually bear no resemblance in their locations in the physical world.

They are a major threat to computing, due to the sheer amount of computers that can be controlled. In 2005 the Dutch police shut down a botnet that controlled 1.5 million computers. 1.5 million computers could shut down any website in the world if they all attempted to access its services at the same time.

Contents 1 Definitions 1.1 Bot 1.2 Herder 1.3 Zombie 1.4 Scrumping 2 How it works 3 Attacks 3.1 DDoS 3.2 Spamming 3.3 Phishing 4 Life Cycle 5 Bot Management 6 How to Fight Botnets 6.1 Norton Anti-Bot 6.2 General Tips 7 References 8 See Also 9 External Links

Definitions

• Bot
• Herder
• Zombie
• Scrumping

Bot

A Bot is short for robot. In the context of this wiki page a bot is a malicious program that installs itself unbeknownest to the owner of the pc, sets up an IRC or HTTP server and is ready to perform illegal activities.

Herder

A person who controls all the bots in the botnet.

Zombie

An infected computer.

Scrumping

A bot stealing CPU cycles from the host computer. This can be used as a positive means if the botnet is configured to not automatically propagate into systems that do not want it. This is not commonly the case. This could be done on a school's network.

How it works

A Botnet basically uses a command and control schema, the same as a military. Each bot has a chain of command that is part of. It distributes orders down the line that it receives from up top. This is beneficial in the fact that it can grow exponentially. This is the opposite of the cell schema that some malware uses, which is to split apart and never communicate once they become big enough.

A bot installs itself onto a PC. It has various vectors to enter that PC that the Herder can set. It does this autonomously. It receives orders from a server that tell it what to do. An individual bot by itself is not that powerful. However an exponential number of bots performing the same action has a much more profound effect.

The bot once installed camouflages itself from the system view. It installs a hidden IRC client. It tries to mask itself by maintaining a low profile by using as little system resources as possible until it receives orders.

Due to the inherent weakness of a command and control scheme, once the higher level bots are compromised the effectiveness of the botnet can be severally reduced. If the main server is taken down, the entire botnet fails.

Attacks

• DDoS
• Spamming
• Phishing

DDoS

A Distributed denial of Service attack. The bots flood a web server with ICMP requests causing the server to crash. This can be used as a method of extortion from various websites. The herder demonstrates the power of his botnet by taking down the website, then he/she contacts the site in question and extorts them for money.

Spamming

A Herder can sell his botnet as a service to a spammer. This is beneficial to the spammer as he can have anonymous distribution of his messages.

Due to the size of some botnets, a spammer will also be able to send much more messages via the bots then he normally could. This is another example of the exponential power of a botnet.

Phishing

Works the same way as the spamming method. However, instead of trying to sell a service such as "P3N15 3NLARGEMENT PILLS" the phisher is trying to con you out of your paypal or bank account.

Life Cycle

• Initial setup of configuration settings of the bot
• Register a Dynamic DNS
• Infect a PC with a bot
  • Bot propagates according to the configuration settings
  • Scans for vulnerabilities
  • Idle
  • Performs actions as received by other bots above it in the chain of command
  • Bot dies:
    • Bot may be taken over by another botnet
    • The bot's owner's PC realizes the PC is a zombie, kills the bot.
    • The chain of command may be compromised above the level.

Bot Management

Bots commonly have hidden removal commands, to completely clean the host computer. On the larger IRC networks such as EFnet channel activity is logged in order to learn the commands, and then automated systems are setup to prevent the owner of the botnet from accessing them and at the same time perform the removal command when a bot comes online to it's control channel.

How to Fight Botnets

Norton Anti-Bot

Norton Anti-Bot is commercial software that scans your system to see if it has become a zombie. It is behavioral based, versus the usual signature based. What this means is unless the bot software actually does something, Norton will leave it alone. It has all the benefits of a commercial software, meaning it will be updated constantly as new bot definitions are found.

General Tips

Use common malware prevention techniques. On Windows XP this includes monitoring the process manager and registry for unknown applications.

A better user could also monitor network traffic and see what ports are in use. A good indication is TCP port 6667 open when an IRC client is not running.

References

"Botnet"

See Also

"Alternative Technologies for Ethernet"
"Phishing"

External Links

"Norton AntiBot"
"Dutch Botnet Suspects Ran 1.5 Million Machines"
--SJakubowski 23:17, 13 April 2008 (EDT)