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Protecting your PC

This note provides some guidelines on what you might wish to do to protect your desktop PC from the various threats to which a networked system is exposed. The intention is to provide some common-sense advice about what can be done to avoid the disruption of having to fix a system where security has been breached. The document makes extensive use, by way of hyperlinks, of documentation already produced by others.

These notes assume your PC is running a version of Microsoft Windows. There are several versions of Windows running on machines in the University and, unless otherwise stated, the default version in this note is Windows 7. Furthermore the advice is for single-user desktop machines rather than server systems. The latter, as the name implies, are computers used to provide services such as a web server or a database system and which typically will have a number of potential users.

The threats

Why protect your system: The consequences of intrusion into your PC can be minor or they can be more serious:

  • strangers may read your email and have access to other personal information
  • your computer may be used to "attack" other computers
  • some of your personal information such as passwords and financial details may be compromised
  • your computer could be made unusable

Virus: the Computer and IT Support web pages already include advice about Viruses. There are literally thousands of computer viruses which cause a range of problems from the minor irritant to the severe disruption of working PCs. They need some means of hopping from one computer to another and can be spread through files on floppy disks, email and its attachments, from web pages and by programs downloaded from the Internet. Some viruses have more sophisticated propagation techniques i.e. once they infect one machine they can use information on that machine as a "springboard" to other systems.

Trojan horse: Trojan horse programs are those which masquerade as something else and often attempt to set up a "back door" that will allow intruders into your system. Typically it is an apparently useful program which contains hidden functions which present a security threat. Once into your system it may be used to monitor or to disrupt that machine or as a starting point to compromise other machines.

Remote access: remote administration of your machine can be achieved in other ways, one being to exploit a security loophole in the operating system or one of its applications. Once installed these programs allow users from elsewhere to access and control your computer.

Denial of service: these are attacks which cause the computer to crash or to freeze because it is overloaded.

Backing up the system and data

Securing the operating aystem

All operating systems are updated after their releases in the form of updates of patches. Some of these address known problems with the software while others deal with security issues. Modern versions of Windows include an update function. This can be set up to run automatically or you can choose to run it periodically. Look for the program Windows Update in the Start menu (bottom left of desktop screen). Patches are often categorised as critical, security or recommended. Note that some updates may be for programs which are not installed on your computer and therefore may not be needed.

[Beware of emails which purport to come from software suppliers and which offer a necessary update. One recent exploit was such an email, supposedly from]

Anti-virus software

Many viruses are spread through email.  ITS, on behalf of the University, manages a site licence for F-Secure which is one of the leading anti-virus products. You are strongly advised to install F-Secure on your PC and it can be downloads from here: Software downloads. It is crucial that the signature files are kept up to date. This can be set up to be done automatically or you can do it manually.

Protecting against intrusions

The risk of unwanted intrusions can only be reduced by sensible settings in the systems configuration.  It is important that you have a secure password set on your PC.  Secondly, Windows offers "file and print sharing" capabilities which enable you to share with others some of the resources on your computer. Unless the use of this facility is absolutely required please ensure that file and print sharing attributes are switched off.

Quick answers

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