Malicious Code: Types, Dangers, and Defenses

Learn how Adaptive Multi-Factor Authentication combats data breaches, weak passwords, and phishing attacks.

The term “malcious code” applies to any type of code that’s made to harm your system, company, or both. Viruses, worms, backdoors, and scripts all fall into this category.

What can malicious code do?

Code makes digital tools work. Malicious code, on the other hand, can make almost anything break.

Once malicious code is deployed within your system, it can spread to other devices, slow down your servers, send data back to a hacker, delete critical information, and more.

A hacker might use code like this to:

  • Steal. Sensitive information, such as bank account data or sensitive passwords, could be worth a lot to a hacker.
  • Harm. A hacker could use code like this to retaliate for some kind of perceived slight, such as an unexpected firing.
  • Play. Some hackers simply enjoy messing with companies and individuals.

Infection can be a serious issue. For example, the WannaCry ransomware worm is a form of malicious code. It spread rapidly in 2017, and victims were prompted to send hackers a fee to make the problem stop.

A few other examples of malicious code include:

Malicious code can also culminate in a backdoor. Essentially, the hacker leaves a spot open and unprotected. A secondary hacker could sneak into that gap and cause yet more harm. Or the original hacker could come back and use that vulnerability later.

Known malicious code infection vectors

No one wants to pick up something that could cause their company harm. But unfortunately, it's easy to get infected.

Malicious code infection methods include:

  • Social engineering. Hackers send messages that seem legitimate. They come from known companies, familiar names, or other reputable signals.
  • Hackers. Bad actors crawl through your code, looking for a way in.
  • Credential theft. Bad actors find an employee’s login data and use it again.
  • Website attacks. Hackers plant code in popup ads or images on reputable-seeming sites.

Engaging with any of these elements by clicking on them or otherwise touching them leads to code deployment.

Malicious code detection and prevention

Bad actors don't want you to know that your systems are infected. After all, the sooner you know there is a problem, the sooner you can remove it. But you can learn to spot signs of infection.

You could be dealing with malicious code if you experience:

  • Slow performance
  • Software running when you load up
  • Strange popups
  • Outside notifications
  • Locked or black screens

Report any of these problems to your IT manager. Traditional antivirus software may spot, isolate, and remove the problem. But sometimes, administrators need to take systems offline to scrub them completely.

Prevent malicious code infections through:

  • Smart clicking. Don't tap on email from sources you don't know. Similarly, don't click on links from people you've never heard of.
  • Software. Run antivirus software on all devices you use for work. Keep all software, including your operating systems, current.
  • Connection protection. Tap into VPNs to do your work if you're on the go, and avoid public servers.


What Is WannaCry Ransomware, How Does It Infect, and Who Was Responsible? (August 2018). CSO.

The Six Most Popular Cyberattack Methods Hackers Use to Attack Your Business. (October 2018). TechRepublic.

6 Tips to Detect Malware On Your Work Computer. (October 2018). Meta Compliance.