About Viruses

A computer virus is a program designed to replicate itself by infecting files and spreading from one computer to another. Viruses can be harmless but are normally designed with malicious intent and can prevent programs from functioning or even destroy data on a disk.

Worms are the most common type of virus which people encounter. Worms are designed to spread automatically via networks (often in email messages) with the owner of the infected machine often completely unaware there is anything wrong.

Trojans (named after the Trojan horse) are programs which pretend to be one thing but are in fact something else. They are usually distributed by viruses and worms to unsuspecting users. A trojan can install Spyware on a machine which will log keystrokes and send details of usernames and passwords to locations specified by the author. Some trojans can perform malicious activities to compromise the security of a machine and can then spread to other systems that it connects to.

How can my PC become infected?

Email attachments and exploits of operating systems or browser vulnerabilities are the most common ways to get a virus on your computer. The infamous Blaster virus spread quickly to unprotected computers when they connected to the Internet by exploiting a security vulnerability in Windows. You should also be cautious when copying files from USB memory sticks or even floppy disks.

How can I tell if my PC has a virus?

Symptoms that your PC may be infected with a virus can include:

• Poor performance
• Applications crashing unexpectedly
• Unusual pop-up windows appearing
• Web pages opening at random

Anti-virus software

IT Services has installed Sophos anti-virus software on all University computers that are managed centrally in order to help protect them from the threat of viruses, see Protection on staff and student PCs.

If you use a PC at home to access University information it is important that you also have adequate protection installed - otherwise you may be putting your University computer and files at risk indirectly; see Protecting your own PC for advice about how you can obtain and install Sophos anti-virus software.

Use of the University's computing services are subject to the University of Leicester Information Security Policy.

Avoiding viruses - Good practice

To help prevent infection and damage caused by viruses you should ensure that you have anti-virus software installed and adopt the following 'good practice' precautions:

1. Avoid opening email received from an unknown sender. If you cannot do this, then be very careful about any attachments to such messages - do not open them until they have been scanned for viruses.
2. Be careful what links you follow on external websites - if you intend to download software, ensure the site you are using is reputable and that it scans anything uploaded to it for viruses.
3. Run Sophos, or any other anti-virus software, before opening files on external storage devices (such as USB pen drives, external HDD or floppy disks)  to check that the files are safe to open.