Malware: presentation of the different malicious programs

The term “malware” brings together different malicious programs installed on third-party computers and causing big problems. Viruses, Trojans and worms are some of the most common types of malware.

What is malware?¶

Malware is the generic term used to refer to malware that can be installed on a computer to perform unwanted functions. It comes from the contraction of the English terms “ wrongicious” (“malicious” in French) and “software » (“software” in French). In this way, malware is completely different from faulty programs which may, for example, not be compatible with certain operating systems, and which are therefore likely to cause errors or crashes. On the contrary, malware is programmed to infiltrate devices or networks and cause damage. In many cases, they go unnoticed for a long time, and the damage can then be very significant. Antivirus programs and firewalls often block malware.

What types of malware exist?¶

There are different types of malware, and sometimes they can be very different from each other. It is essential that cybercriminals have programming knowledge and understand the intentions of a malware program if they wish to achieve their goals. Viruses, Trojan horses or worms are among the most well-known types of malware. Some malware even combines different types of malware. Below you will find the best known of them:

Computer viruses¶

The term “virus” is often used as a synonym for the word “malware”. This shortcut is not always correct, but computer viruses do indeed represent a significant portion of malware. However, there are differences from one virus to another. All computer viruses share one thing in common: they create copies of themselves in order to self-broadcast on a system or in a network. All of these malware, however, can have different objectives. Some viruses are indeed used to harm a system, to overload it, or even to destroy it, but others have the main mission of secretly spying on systems to steal, for example, their sensitive data. Viruses are the oldest form of malware.

Trojan horses¶

Trojan horses are another of the most well-known types of malware. This name comes from Greek mythology: soldiers hid in the hollow belly of a large wooden horse, and were thus able to infiltrate the ancient city of Troy without being noticed. Malware of this type works like this: under the cover of a harmless, or even useful, program, Trojan horsesonce installed, secretly monitor their host system, copy data or allow other types of malware to access the targeted system. It is even possible to control some of these malicious programs remotely.

Computer worms¶

Computer worms are malware comparable to computer viruses, but they enjoy greater independence from the latter. Viruses must indeed be attached to files, while worms do not require no host file. They are capable of copying and spreading themselves, to cause significant damage within a system or even copy its data. They can use networks, external data carriers, emails or messaging services to spread.

Ransomware¶

Ransomware fraudulently gains access to a system and encrypts the files it contains. So users can no longer reach them. They receive a message informing them that they will be able to access their system again once they pay a “ransom”. The name of this malware therefore comes from the English term “ransom” (which, in French, means “ransom”). However, it is not recommended to comply with cybercriminals' requests, as there is no guarantee that they will allow victims to regain access to their data once payment is received. Check out our digital guide to learn how to get rid of ransomware.

Spyware¶

Spyware is used to spy in secret computers or other third-party systems. The data thus collected can then be used for personal purposes, or even communicated to other third parties. While this malware has no direct negative influence on the system, it can still place sensitive data in the hands of malicious people.

Scareware¶

The term “scareware” comes from the English “scare”, which means “to scare”. Affected users receive false warning messages intended to worry them, or to push them to download a program to protect themselves from an alleged threat. If the latter is not downloaded, it often allows the installation of other malware on the affected computer.

Examples of known malware¶

So there are different varieties of malware. You have probably already heard about malware attacks, or read articles about them. Discover with us some of the best-known examples:

ILOVEYOU¶

ILOVEYOU was a precursor for many other computer viruses. This malware was often sent by email during 2000; these messages were opened by thousands of unsuspecting users. This malware then immediately « replicated », that is, it was sent to the victims' contacts; he was thus able to cause serious damage to all systems. ILOVEYOU, however, made it possible to raise public awareness of the dangers of computer viruses.

Emotet¶

Emotet is a Trojan horse first identified in 2014. This malware copies email addresses, sender names and subject lines to in turn send falsely authentic emails. If recipients click on the attachment, other malware is installed on their devices; they can in turn paralyze systemsor copy sensitive data, such as banking information.

MyDoom¶

The MyDoom computer worm has been targeting Windows computers since 2004. The damage caused by this malware is already estimated at nearly 40 billion US dollars. To this day, its origins remain unclear, despite the presence of the line “Andy; I'm just doing my job, nothing personal, sorry » in the code. This worm reproduces, and copies are sent by email At the height of his glory, MyDoom managed to slow down the speed of the global Internet by 10%. Initially, the malware primarily targeted Microsoft and the SCO group.

WannaCry¶

WannaCry is a malware program that made headlines in 2017 around the world. This ransomware managed to encrypt files on several thousand computers, each time demanding a “ransom” of 300 US dollars (to be paid in Bitcoin). This malware exploited one of Windows' security vulnerabilities to achieve its ends. Because of WannaCry, the NHS (National Health Service, in French “national health system”) was forced to postpone important operations because it was no longer possible to access patient records. Other international companies, including Nissan, FedEx and Deutsche Bahn AG, have also been targeted by this malware. The damage caused would amount to nearly 4 billion US dollars.

Pegasus¶

Pegasus is spyware created by the Israeli company NSO Group. It is mainly used to spy on smartphones running iOS and Android. This company's customers would primarily be States seeking only to use this software to conduct criminal investigations and fight terrorism. However, this spyware today finds itself under fire, because certain countries are also suspected of using it to monitor their opponents or other people deemed “troublesome”.

BKA-Trojaner¶

BKA-Trojaner is a German Trojan hybrid, halfway between scareware and ransomware. When victims turn on their computer, a message is displayed in full screen instead of the home page; he tells them that the BKA (“Bundeskriminalamt”, or the “Federal Criminal Police Office”) has, for example, found child pornography on their computer, but that he is prepared not to pursue the investigation in exchange for a one-time payment. Appearing for the first time in 2011, this malware caused significant damage, despite a presentation that was clearly amateur work.