What Are Malware Bots: Malicious Spiders, Crawlers and Web Bots

What Are Malware Bots: Malicious Spiders, Crawlers and Web Bots
Graphic: Nathaniel Blum

What Are Malware Bots: Malicious Spiders, Crawlers and Web Bots

Emily Long
Updated July 1, 2020

If your computer is running slower than normal, your browsing speed has dropped or you’re getting an abnormal amount of pop-up spam, you may be a victim of a malicious bot.

Bots aren’t always bad, but these sneaky crawlers can move quickly to crack codes, steal information and impact your devices without your knowledge. Here’s how to identify, fight and prevent malicious bots.

What are internet bots and how do they work?

“Bot” is short for “internet robot.” You can think of a bot as a spider that crawls around the web of the internet gathering information, making connections and relaying messages. They’re programmed to perform specific tasks automatically and much faster than any human could.

Internet bots were originally intended to do good. For example, you interact with bots when you go through an automated customer service chat or instant message. Good bots also ensure you find what you’re looking for on the internet by powering internet search engines such as Google and Bing.

There are bad bots, however. Malicious internet bots may spread spam, commit cybercrimes, collect private information without consent, attack computer systems and more. According to a 2019 report from Distil Networks, bad bots account for 20.4% of all internet traffic. Good bots account for 17.5%, and human activity makes up the remaining 62.1%.

The same data shows that the financial industry is the hardest hit by bad bots, which are generally trying to obtain user account information. Other bots perform similarly dangerous functions: Election bots may interfere with voter registration accounts, while e-commerce bots commit credit card fraud and steal user credentials.

Related: Identity theft check: _Uncover if your data may have been compromised _

What do malicious bots do?

As we’ve mentioned, bad bots can do everything from slow your internet browsing experience to collect data that’s used to steal your identity. Plus, bad bots can multiply on their own.

Here are a few types of attacks malicious bots perform.

Credential stuffing

This is a type of cyberattack in which bots take usernames and passwords obtained from a data breach and use them en masse in an attempt to log into another service (like a bank). The hope is that at least some of those credentials will open doors elsewhere.

Web/content scraping

In this process, bots download (or scrape) a website’s content, which may be used to violate copyrights or steal internet traffic.

Email address and data harvesting

Bots use a variety of methods to collect large numbers of email addresses, which can be used by spammers to send bulk (unsolicited) emails.

DoS attacks

In a denial-of-service attack, bots use their speed and automation to flood a website with so much traffic that it crashes—meaning legitimate users aren’t able to access the page or service they need.

Brute force password cracking

Bots may also try to brute force their way into secure data, trying different password combinations at blistering speeds until they find one that works.

“Bots are not necessarily targeting an individual per se,” said Matt Keil, director of product marketing at Cequence Security. “They are targeting a wide swath of users from the billions of stolen credentials, counting on weak or reused passwords.”

Bots are able to collect bulk data quickly and quietly. In addition to the attacks listed above, malicious bots may also log keystrokes or exploit existing vulnerabilities in computers caused by viruses.

How do I know if my computer is infected by bots?

There are a few signs to watch for to determine if malicious bots have infected your device.

  • Your computer or internet browser runs slowly or crashes often and for no reason.
  • You get pop-ups when you’re not using your browser.
  • Device settings change mysteriously.
  • The device’s fan runs even when you aren’t using it.
  • Your contacts receive emails from you that you didn’t send.

If you believe your machine has been infected, you have a few options. The most severe is to do a factory reset, which will get rid of everything on your computer. There are also scans you can do to identify a botnet. However, security experts also say that many infections last less than a day, so you may not have much to worry about.


To avoid the consequences of malicious bots, follow the same digital hygiene practices you would to protect your personal information from any other security attack.

First, never click on links received via email or on social media, and don’t fall for scary messages or pop-ups that tell you to do so. Spam links may force you to download malware or spyware, which could infect your computer and give bad actors access to your data. If you’re unsure whether a message is legit, use a reverse email search lookup service to potentially identify the sender.

Next, use different login credentials for every single account. If your username and password are compromised in a data breach, a bot can use credential stuffing to access an account that uses the same information. Update your accounts with strong passwords, and store your logins in a password manager.

Finally, use firewalls and antivirus software on your devices, and always enable software updates, which help patch security vulnerabilities.

While you can’t eliminate the risks bots pose, you can minimize them.

Disclaimer: The above is solely intended for informational purposes and in no way constitutes legal advice or specific recommendations.