It sounds like something out of a sci-fi movie: your computer is infected with a virus and “conscripted” into a larger army of compromised devices. However, botnets are a very real tool that cybercriminals use every day to carry out their activities.

So, what is a botnet, and how can you tell if your computer is part of one?

What Is a Botnet?

A botnet is a collection of devices “recruited” by cybercriminals, infecting each one with malware. This malware runs silently in the background, so the owners of these devices don’t even know their device is part of a larger network used to attack others.

A botnet’s strength correlates to the number of devices infected and added to the network. The more devices in a botnet, the more power the owner has when performing attacks.

How Hackers “Recruit” Devices to the Botnet

Devices are infected with a specific type of malware and added to the network. Each device is typically infected with the same malware, usually in infected email attachments or files downloaded from shady sources.

Once the malware gets onto your PC, it keeps a low profile to avoid detection. It only springs to action when the person running the botnet commands it.

How Hackers Use a Botnet

Once a bad actor builds up a huge botnet, they can use it to perform tasks that would usually require a lot of PCs. The more well-known task is aDirect Denial of Service(DDoS) attack that uses every member of the botnet to swarm a single server with requests and force it offline.

Cybercriminals can also use botnets to send out lots of spam. If they set up each PC in the botnet to begin churning out emails, the sheer numbers can cause a deluge of mail to hit people’s inboxes. The email contents can vary depending on what the cybercriminal wants to achieve; they may sendfraud or phishing emailsor send infected attachments to recruit even more devices into the botnet.

The Different Kinds of Botnet

When a cybercriminal wants to send commands to their botnet, they can choose between a centralized and a decentralized model.

In a centralized model, the botnet owner has command servers that each computer connects to. When the cybercriminal wants their botnet to perform a specific task, they send a request via a command and control server. The zombie devices receive the message via this server and execute the command. Cybercriminals can use apps like IRC or Discord to send commands to their bots, constantly checking their channels for new entries. In fact, theDISGOMOJI malware uses emojis sent in a Discord channelto execute commands.

In a decentralized model, each botnet member is connected. The cybercriminal sends a command, which passes from one device to another. It’s trickier for a cybercriminal to create a decentralized botnet, but it does mean they don’t have to rely on a server to send out commands, making it difficult for law enforcement to disassemble the network.

How to Tell If Your PC is Part of a Botnet

If you’re worried about botnets, the good news is that you can prevent or reclaim your PC from a cybercriminal’s botnet.

1. Install a Good Antivirus

The best way to prevent your PC from becoming part of a botnet is toinstall a good antivirus program. These should identify botnet malware before it can infect your PC and prevent it from becoming a “zombie” in a cybercriminal’s plans.

2. Keep an Eye Out for Suspicious Activity

Failing that, it can be hard to identify that your computer is part of a botnet. After all, cybercriminals want their activities to go under the radar, so you shouldn’t notice any issues right away. However, if you notice that your PC’s resources are being sent into overdrive without you doing or opening anything, it may be because it’s busy working away on a malicious app’s commands. Similarly, if your internet feels slower than usual, it may be because your computer is sending out requests as part of a botnet.

If the above problems occur with your PC, try disconnecting it from the internet. If this fixes the issue, there’s a good chance it’s receiving commands from an external source. Download an antivirus app and scan your PC to catch any nasty malware lurking on your device.

3. Factory Reset Your PC

If push comes to shove, you canfactory reset your PCto scrub the malware from your PC. It’s a little overkill, but it’s the best way to eliminate malware that has gone undetected by an antivirus program. By starting again with a clean slate, you can be sure that no malicious apps are running in the background.

While botnets sound scary, there are ways to keep your device from being recruited into one. Even if you suspect your device is part of one, it’s still not too late to break the cybercriminal’s grip on it.