What is malware?

Malware refers to malicious software that’s planted on someone else’s computer, often causing sig­ni­fic­ant issues. The most widely re­cog­nised types of malware include viruses, Trojan horses, and worms.

What is malware?

Malware is a general term for malicious programs that can be smuggled onto a computer and perform unwanted actions there. The term is a com­bin­a­tion of ‘MALicious’ and ‘softWARE’. It is distinct from faulty programs that may cause errors or crashes due to com­pat­ib­il­ity issues with an operating system. Malware is de­lib­er­ately designed to in­filt­rate devices or networks with the aim of causing harm, sometimes operating unnoticed for extended periods and in­flict­ing sub­stan­tial damage. Antivirus programs and firewalls are often effective in thwarting malware attacks.

What are the types of malware?

There are various types of malware, some of which differ massively from one another. It’s important to un­der­stand the pro­gram­ming and in­ten­tions of a malicious program, es­pe­cially when it comes to dealing with it properly. The best-known types include viruses, Trojans and worms. Some malware programs also combine different types. The best known are:

Computer viruses

The term ‘virus’ is often used in­ter­change­ably with malware, although it’s not always accurate. Computer viruses do con­sti­tute a sig­ni­fic­ant portion of malware, but there are dis­tinc­tions even among viruses. What all computer viruses share in common is their ability to replicate them­selves, spreading autonom­ously within a system or across a network. The ob­ject­ives of these viruses can vary. Some aim to com­prom­ise, overwhelm, or even disrupt a system, while others primarily operate covertly to spy on systems and capture sensitive data, for instance. Viruses represent the oldest form of malware.

Trojan horses

Another very well-known type of malware is the Trojan horse, which is often referred to as Trojan for the sake of sim­pli­city. This name draws from Greek mythology, where a wooden horse concealed soldiers who in­filt­rated the city of Troy unnoticed. This type of malware works in a very similar way as it pretends to be a harmless or perhaps even useful program. Once installed, Trojan horses covertly surveil the host system, replicate data, or create pathways for other types of malware. Some of these malicious programs even allow remote control of the com­prom­ised system.

Computer worms

Computer worms share sim­il­ar­it­ies with malware such as computer viruses but are even more self-reliant. Unlike viruses that attach to other files, worms don’t need a host file. They copy and spread on their own and can then cause great damage or copy data in a system. They spread via networks, external data media, emails or messaging services.

Ransom­ware

Ransom­ware gains access to a system and encrypts files. As a result, users can no longer access the data. A no­ti­fic­a­tion informs them that full access to their system will only be restored upon payment of a ransom. Con­sequently, the name of this malware is derived from ‘ransom’. However, it is strongly re­com­men­ded not to comply with these demands as there are no as­sur­ances that the cy­ber­crim­in­als will actually decrypt the data after payment. You can find in­struc­tions on how to remove Ransom­ware in our Digital Guide.

Spyware

Spyware is used to secretly spy on other people’s computers or systems. The data obtained in this way is then either used for their own purposes or passed on to third parties. This malware does not have a direct negative impact on the system; damage is rather caused by the fact that sensitive data can fall into the wrong hands.

Scareware

The term scareware is derived from the word ‘scare’. Users are shown fake warnings that are intended either to worry them or to encourage them to download a program against a supposed threat. Once down­loaded, it often installs further malware on the computer.

Examples of well-known malware

Malware is thus divided into different subtypes. It’s likely that you’ve already heard or read about specific malware programs. The best-known include:

ILOVEYOU

The precursor to many sub­sequent computer viruses was ILOVEYOU. In 2000, this malware was dis­trib­uted via email and opened by numerous un­sus­pect­ing users. Upon ac­tiv­a­tion, it rapidly rep­lic­ated itself, sending copies to other contacts and in­flict­ing sig­ni­fic­ant damage to systems. ILOVEYOU heightened awareness about the threat posed by computer viruses.

Emotet

Emotet, a Trojan horse initially dis­covered in 2014, operates by copying email addresses, sender names, and headers to craft deceptive emails. When re­cip­i­ents click on the at­tach­ments, ad­di­tion­al malware is installed, capable of either crippling systems or stealing sensitive in­form­a­tion such as bank details.

MyDoom

The MyDoom computer worm has been targeting Windows computers since 2004, causing an estimated $40 billion (around £33 billion) in damages. Its origins remain unclear, although a line of code within it reads, ‘andy; i’m just doing my job, nothing personal, sorry’. This worm rep­lic­ates and spreads copies via email. At its peak, MyDoom even managed to slow down the global internet by 10 percent. Initially, it primarily targeted Microsoft and the SCO Group.

WannaCry

WannaCry is the name of a malicious program that garnered worldwide attention in May 2017. This ransom­ware encrypted files on thousands of computers and demanded a $300 (around £250) Bitcoin ransom for each de­cryp­tion. It exploited a Windows security vul­ner­ab­il­ity. As a result, the British health­care or­gan­isa­tion NHS had to delay critical surgeries due to in­ac­cess­ible patient records. Global companies like Nissan, FedEx, and Deutsche Bahn also suffered from the malware, causing an estimated four billion dollars (just over three billions pounds).

Pegasus

The Pegasus spyware, developed by the Israeli NSO Group, is primarily employed for sur­veil­lance on iOS and Android smart­phones. NSO Group’s clients are pre­dom­in­antly states, and they claim to use the software solely for crime detection and coun­terter­ror­ism purposes. However, there has been sig­ni­fic­ant criticism of this spyware, as it is suspected that some countries may also use it to monitor op­pos­i­tion figures or in­di­vidu­als critical of the gov­ern­ment.

BKA Trojans

The BKA Trojan is a hybrid of scareware and ransom­ware. When users booted up their computers, they were greeted with a full-page ad­vert­ise­ment in place of the usual home screen. The ad falsely claimed that the Federal Criminal Police Office had dis­covered child por­no­graphy on the computer, among other things. It offered to forgo further in­vest­ig­a­tions in exchange for a one-time payment. Despite its am­a­teur­ish ap­pear­ance, this malware first emerged in 2011 and caused sig­ni­fic­ant harm.