• A computer virus is a program that is not oriented towards the computer user and whose actions are not based on the interests of the computer user.
  The virus is designed to disrupt the operation of the computer, corrupt data stored on the disk, create access rights for other users/hackers, collect passwords and forward them, and do similar things.
  Viruses also paralyze the operation of the computer network, creating excess traffic on the network.
• Viruses spread by mail (e-mail) send virus-infected letters to any address with any sender name.
• A number of viruses using social networks are also common, spreading using different communication software (E-mail, Facebook, etc.).
• The bad guy spreads himself by sending links to contacts through the social network, giving the impression that a friend wants to send some interesting link or file.
• In fact, clicking on the link downloads a malware program that explores the back rooms of the computer and starts sending the virus from the infected computer to other contacts.

• Just as the mythical Trojan horse looked like a gift but contained Greek soldiers who conquered the city of Troy, today's Trojan horses are computer programs that look useful but actually threaten your security and can do a lot of damage.
• Trojan horses are, for example, e-mail messages with an attachment containing a Trojan. The letter may appear as a promotional offer or a letter from a friend, but in fact, the Trojan attached to the letter is trying to turn off the computer's anti-virus and firewall.
• NB! If the sender of the letter is unknown or if an acquaintance has for some reason started sending suspicious letters, the letter should either be deleted or asked about the letter before opening it.
  Maybe a friend's computer is infected and is sending infected emails without his knowledge.

Trojans spread by luring people to run programs that appear to come from a safe source. Trojan horses can also be attached to software that you download for free.
Never download software from a source you don't trust.

• Unlike the flu virus, computer viruses spread at any time of the year and in any weather. They spread along with files on USB sticks and CDs, as well as over a computer network by e-mail or by visiting infected web pages.
  Many computer users have at some point discovered that their files have been corrupted and cannot be recovered, or the computer is behaving strangely and preventing them from continuing their daily work. Computer viruses are often the cause of such situations.
• The main signs of a computer virus infection are as follows:
  • Spontaneous behavior of the computer, windows that pop up without the user's request, changes to the browser's home page.
  • Unprecedented appearance of suspicious files.
  • An increase in the operational memory in use compared to the normal operating mode.
  • The appearance of various unexpected video and/or audio effects.

We advise that you quickly examine your computer for infections if any of the aforementioned symptoms or other suspicious indications (such as erratic behaviour, frequent spontaneous restarts, etc.) arise.

• Verify your operating system's most recent updates.
• On your PC, always run antivirus software.
• Even if the sender is someone you know, be cautious when opening attachments in emails and files shared on social media. It might instead be a virus that nestled in his computer.
• It is preferable to call and enquire if the letter's content does not make it apparent why a file is attached and that the sender actually wants you to view it.
• To give others more confidence, when you add a file to an email, be sure to include a description of the file(s) and your reasoning in your own words.
• Use a personal firewall to shield your computer from hackers and internet users looking for security flaws, as well as to stop viruses from spreading to other computers.

If the above symptoms, as well as other suspicious manifestations (uncertain operation, frequent spontaneous restarts, etc.) appear in the computer, we recommend that you immediately check your computer for viruses.

Computers managed by the university's IT department have the necessary security measures automatically in use, and you don't have to worry about Windows updates or virus protection.

All personal computers running Windows 7, Windows 8 and Windows 10 should upgrade their computers to Microsoft Windows 11.

Machines installed by the University of Tartu already have virus protection installed by the University of Tartu.

The Windows 11 operating system comes with a free anti-malware engine called Microsoft Defender Antivirus. It provides real-time defence against every kind of malware imaginable, including viruses, spyware, and malware. The functioning of Windows Security will not be impacted by the installation of a third-party antivirus, however Microsoft Defender Antivirus will be automatically blocked.

Virus scan

To start a virus scan with Microsoft Defender, follow these steps:

1. Open start menu.
2. Select Settings.
3. Click on Update & Security.
4. Open Windows Security.
5. Click on Virus & threat protection.
6. Click on Quick scan.

Full virus scan

A full virus scan will take longer, but it will definitely check all files, folders and applications.
To start a full virus scan with Microsoft Defender, follow these steps.

1. Open start menu.
2. Select Settings.
3. Click on Update & Security.
4. Click on Virus & threat protection.
5. Click on Scan Options.
6. Click on Full Scan.
7. Click on Scan now.