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How Malware Types Differ: Trojans, Spyware, and Adware

Malware Stock Image: Hand holding a smartphone with a large warning sign in the background
Malware is a serious problem for many users in the age of the internet. Photo: Getty Images
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Adrian Mühlroth

December 7, 2023, 3:35 pm | Read time: 3 minutes

The term malware is familiar to everyone today, and we know to be cautious of it. But what exactly is behind it, and what types of malware are there?

In the digital age, malicious software–also known as malware–poses a serious threat to online security and privacy. TECHBOOK explains the differences between three common types of malicious software: spyware, trojans, and adware.

What is Malware?

The term malware is derived from the words “malicious software.” Synonyms often used include harmful software or malicious programs.

As the name suggests, malware is programmed with the intent to cause harm to the affected device. One goal might be to steal data or damage the software to the point that the device becomes unusable; this depends on the type of malware. TECHBOOK introduces the three most common types.

Spyware Secretly Collects Information

Spyware is designed to secretly gather information about a user or their activities without their knowledge or consent. It “spies” on the user in the truest sense of the word.

Spyware can record keystrokes, log browsing history, record conversations, take screenshots, and access personal information such as usernames, passwords, and credit card data. It typically operates unnoticed in the background, making it difficult for the user to detect.

Trojans–Disguised Malware

A trojan deceives users by masquerading as legitimate software or files. This allows the software to enable unauthorized access, steal data, destroy files, spy, or recruit infected computers into botnets, which can then be used for further attacks.

Trojans are disguised, operate covertly, and do not self-replicate–unlike traditional computer viruses. However, they can evolve to avoid detection. Incidentally, this type of malware is named after the Trojan Horse from mythology, where the Greeks gained access to the supposedly impregnable city of Troy by hiding warriors inside a large horse statue.

Related: 3 Quick Tips to Spot Phishing Emails at a Glance

Adware Generates Unwanted Ads

The portmanteau stands for “advertising-supported software.” Adware primarily aims to display unwanted advertisements to the user. The malicious software is often bundled with legitimate software or installed without the user’s knowledge. It generates pop-up ads or redirects web browsers to ad-laden websites.

The creators of adware attempt to generate revenue through advertising and marketing partnerships. While adware is also malware, it does not necessarily steal personal data or damage the system.

How to Protect Yourself from Malware

To protect against these threats, it is important to have reliable antivirus software. This should always be kept up to date–most providers automatically suggest updates. An outdated antivirus program may still offer some protection, but it is far less effective and may not respond to new malware.

Additionally, to generally avoid malware, practice safe internet browsing habits. For example, visit only reputable websites and do not click on links from unsecured sources, such as in emails. The same applies to downloads, such as new software.

This article is a machine translation of the original German version of TECHBOOK and has been reviewed for accuracy and quality by a native speaker. For feedback, please contact us at info@techbook.de.

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