Botnet Zombie Apocalypse: How to Protect Your Computer

Botnet Zombie Apocalypse: How to Protect Your Computer

The list of internet baddies is long. There are countless iterations and permutations of malicious software, whether in script or code form, which fall under the all-encompassing designation  malware.  Under that designation, there are many subcategories, such as viruses, worms, spyware, keyloggers, adware, rootkits, backdoors, Trojans and botnets. While most, if not all, computer users are familiar with viruses and the necessity of using antivirus software and antimalware applications to protect their computers, not everyone understands the distinctions between other types of malware, like rootkits and botnets, for example. For further information, read our reviews of the best Mac internet security software.

What is a Botnet?

Simply put, a bot   which is short for robot   is an automated computer program that allows outside sources to control computers remotely without the users' knowledge. A botnet is a network of hundreds or thousands of computers infected with botnet malware that communicates covertly with a command-and-control (CnC) server run by a type of cybercriminal called a botmaster. Unbeknownst to the individual users, their computers are linked in a rogue network, which the botmaster can utilize for a variety of nefarious purposes. Hackers primarily use botnets to accomplish one or more of the following three main objectives, listed here in no particular order.

The first is something you've doubtless encountered, whether your computer is part of a botnet or not: email spam. Spammers pay botmasters to send an enormous number of spam email messages with their botnets. The messages' origins are difficult to detect, and therefore prevent, because each computer within the botnet may send only 100 messages, which doesn't raise any red flags. All it takes to send one million messages, for example, is a botnet of 10,000 zombie computers.

The second utilization is to steal identity information and user credentials like bank account and credit card numbers, usernames and passwords from the computers on the botnet. Depending on the type of malware used to create the botnet, the botmaster can monitor your keystrokes, harvest your personal information and hijack your internet browser, among other things.

The third is launching massive distributed denial-of-service (DDoS) attacks to cripple websites and deny legitimate users access to the targeted sites, which the botmaster can use to hold the site owner hostage and make demands. In a DDoS attack, the botmaster harnesses the computers in the botnet to inundate a website with an overwhelming amount of simultaneous traffic that the targeted site's servers cannot process, crashing the servers and rendering the site inaccessible to everyone. The botmaster then makes ransom demands, and maintains the DDoS attack until the site owner agrees to the hacker's demands or figures out how to block traffic from the botnet. Usually, the former happens before the latter.

How Did My Computer Become a Botnet Zombie?

For your computer to become an infected botnet zombie, it must be exposed to zombie-making malware. The ways in which your computer can become infected are common to most malicious software. Without even realizing what is happening, you can inadvertently download a botnet Trojan by visiting unsecure or malicious websites, downloading unverified files or software, clicking on links in email messages, opening infected email attachments or simply by connecting to an infected network.

Trojan botnet code is often hidden in email attachments disguised as innocuous Excel, Word or JPG files. Hackers can disguise bot malware using a number of tactics, the simplest of which is merely changing the file extension to hide executable (EXE) files. You may think you're opening a picture of a cute kitten, but in fact, it's much worse than that. Sometimes the malicious code is a script or a macro within a document file. If you open the infected file, it will secretly run the botnet installation file without informing you. Once this happens, the bot will hide itself deep inside your system and begin communicating with the botmaster's CnC server.

How Do I Detect a Botnet Infection?

Although antivirus software will often miss bot incursions and infections, there are a few telltale signs to watch for that indicate your computer has been co-opted by a botnet.

  • Your computer is unusually slow, crashes or frequently stops responding to commands
  • Your network or internet connection is unusually slow
  • There is unknown network activity when you're not using the internet
  • Your computer cannot access some or any websites
  • The amount of spam you receive dramatically increases
  • Your firewall alerts you to unknown programs or processes trying to access the internet

If your computer regularly exhibits several of these symptoms, it is most likely infected with malware and could be part of a botnet. At this point, you should download and run a malicious-software detection tool to scan your system for malware. The Windows Malicious Software Removal Tool is a free way to scan for botnet infections.

How Do I Remove a Botnet Infection?

Once you've determined your computer has been hijacked by a botnet, you should immediately take action to rid your system of the dangerous infection. You might want to enlist the help of a computer security expert skilled in malware detection and removal. If you prefer to tackle the problem yourself, here are the steps to follow:

  • Download and install antivirus and antimalware  software, or update your existing software
  • Download and run a specialized removal tool such as RUBotted or AntiBot
  • Remove any malware these applications detect
  • Repeat the scans until your system no longer exhibits symptoms of a botnet infection

How Do I Prevent a Botnet Infection?

Once you've rooted out and removed the bot malware, you won't want to go through the ordeal again. After removing the malware   or if you discover that your computer is not infected   take the following precautions to protect your computer from future attacks:

  • Make sure your operating system is up to date, and enable automatic updates
  • Update your security software and enable it to run constantly in the background
  • Make sure all your software applications are up to date
  • Set up a strong firewall and configure it to alert you whenever a program or process attempts to access the internet
  • Change all your login credentials and create strong passwords that are difficult to guess
  • Avoid all suspicious or unverified websites and don't click on unknown links
  • Don't download unverified software or files
  • Be suspicious of all email messages and do not open any from senders you don't recognize
  • Use intrusion-detection and intrusion-prevention systems
  • Subscribe to a web-filtering service to monitor your internet activity in real time
  • Don't leave your computer on and connected to the internet 24 hours a day
  • If you use Internet Explorer or Firefox, switch browsers, because the majority of malware is written for these applications

Unfortunately, between five million and 10 million computers are currently entrenched in botnets, so it's a prevalent problem and significant security concern. However, if you follow these suggestions, pay attention to your system's running processes and exercise caution and good judgment while you're online, you should be able to inoculate your computer system and avoid a future botnet infection.

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