What is a computer worm?

When it comes to computer malware, what is a worm? What is the difference to Virus and for Trojan horse? And what are the dangers of this malware, which has been around since 1988? I will answer these and other questions in the following paragraphs. In the end, you not only know the answer to the question What is a computer worm?, but also have enough background information to understand the topic a little more deeply. Do you have any questions or comments? Then please leave a comment.

What is a computer worm, how does it work and how can you delete it? These and other questions about worms in computers are answered here.
What is a computer worm, how does it work and how can you delete it? These and other questions about worms in computers are answered here.

Where does the name worm / computer worm come from?

The name for this type of malware comes from the way it works and spreads. A computer worm is capable of replicating and sending itself. This requires a network or appropriate removable media - such as a USB stick or an external hard drive - but both are part of everyday life today. 

The first of its kind was the Morris Internet worm, written and distributed by Robert T. Morris in 1988. Although the Morris worm did not contain any directly harmful elements, it was able to spread over the then existing Internet and local networks, thus consuming quite a lot of resources. Some systems are said to have been completely paralyzed as a result.

How does a computer worm work?

A worm for computers, smartphones and other devices where it can spread arrives through emails, downloads, questionable websites, USB sticks or devices, and possibly other sources. The software can duplicate itself and attach or nest on specific digital hosts. E-mail clients such as Outlook, Mail, Thunderbird and apps from e-mail providers (GMX, Web.de, Yahoo, etc.) are popular for rapid distribution.

In these programs, an e-mail is then sent to all contacts or addresses in the Sent mailbox. These may contain a copy of the worm as an attachment or a link to a website where the worm and/or other malware is downloaded. In addition to spreading itself, the computer worm itself can damage the system or inject other harmful programs or scripts. This results in overlaps with the computer virus and the Trojan horse.

Other ways of spreading computer worms

Email and client programs for managing email have been around for a long time and will be around for a very long time. Accordingly, they are a stable means of spreading not only computer worms but also numerous other malware. The often mistaken "I Love You"Virus The aforementioned chain letter from the year 2000 with ILOVEYOU in the subject and Loveletter as an attachment was, for example, a Worm. Onel de Guzmán's malicious code was written in Visual Basic Script and measured just 10 kilobytes.

However, worms can also be circulated in other ways or spread themselves. Also via messenger apps like WhatsApp, Telegram, Signal, Skype, iMessage, Threema and Co., links, files and scripts can circulate independently. The situation is similar with IRC worms for Internet Relay Chats. Worms for peer-to-peer connections, i.e. computers that communicate directly and without intermediate servers, are called P2P worms. There are also some for removable media and USB devices or small devices. However, the fact that there are so many ways of spreading does not automatically mean that worms are lurking around every corner.

How do I recognize a worm on the computer?

Depending on the type and how it spreads, there can be various signs of a computer worm. You can recognize an e-mail worm, for example, by the fact that you suddenly have numerous e-mails with questionable attachments or links in the text in the outbox or in the sent folder. Other programs, such as chat software, can also contain messages that you did not write yourself and that spread the worm further.

An indication of malware is always a higher consumption of resources. So if the computer runs slower than usual with a certain program, runs hot, makes the fans rotate faster and so on, then this can be an indication. Depending on the program and the exploited vulnerability / security gap, it is also possible that the infection with a worm is not discovered. Perhaps it only reveals itself through other software that has been smuggled in.

A computer worm can fulfill other functions in addition to spreading itself. From deleting user folders or the entire hard drive (virus function) to injecting additional malware (Trojan function) – e.g. B. to spy on passwords or to record keystrokes, audio, video and Co. (spyware and stalkerware) – there can be a lot. Also encrypting the hard drive as Ransomware or creating a backdoor as Rootkit for further attacks can theoretically be enabled.

How do I get rid of a computer worm?

If there are signs that the system or individual apps have been infected by a computer worm, then the greatest damage has probably already been done. However, the worm itself will not stop its activities once it has spread. Rather, depending on the type and scope of his code, he will repeatedly use the exploitable distribution option to send himself to other systems and users. That's why you have to be active.

Common anti-virus and anti-malware programs contain the corresponding signatures for known malware. Before Kaspersky was warned, and also Avast as well as CCleaner should not be trusted. However, there are other protection software, such as Malwarebytes, Intego Mac Internet Security, G Data and Co. What can also help: delete the hard drive and reinstall the operating system. Programs and executable files should not be dragged to an external hard drive or the cloud for replay.

How can I protect myself from computer worms?

At Sir Apfelot, we're not big fans of antivirus programs on the Apple Mac. Because macOS already offers numerous protective mechanisms. In addition, we rely on reasonable use of the Internet and its numerous possibilities. If you avoid attachments and links from unknown e-mail addresses or messenger contacts, no dubious websites and software only from reliable sources then you are already doing a lot of things right. Here's more on the topic: Find an app's official download page.

Sources: 1, 2, 3

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