Wednesday 19th August
Keeping the nasties at bay (Tim & Roger)

A look at how keep your computer and our school network safe from nasties like computer viruses. Ways of preventing, scanning and cleaning viruses to keep your precious work and computer from becoming a victim. We'll also cover considerations you'll need to make to manage situations when other people want to connect their computer to our network.



Ok - the first step is KNOWLEDGE

What are Viruses and Spyware?

Viruses generally are designed to INFECT multiple computers and cause harm in some way. They can spead via email, downloads, websites, USB and thumb drives, networks etc. Viruses are distinct from Trojans (which hide from view and generally try and do something in the background, for example allow access to your computer from other computers) and also from Worms, which don't have a "host" program they are attached to. But they are all designed to cause harm of differing kinds. Most viruses will not cause so much harm that you will lose all your files on the computer but you may lose some and the virus may stop yiour comopuyter from being able to boot without removal of the virus and repair of critical files. Generally a technician will be able to repair it without wiping your computer. In some cases though a reinstall of the operating system may be needed. (I've not had to do this yet).
Spyware is software that is installed (usually unwittingly) and which collects information about the user without their knowledge and usually sends it on somewhere. It may be passwords, keystrokes, or other less harmful activities like sites the user has visited. Not generally as dangerous as viruses (but if you lose your internet banking passwords it could be!)

About files on your computer

Understanding about what kinds of files exist on your computer (identified by a 3 character file extension) is important. I always turn on the option to display the types of file because they may be hidden by default. To display them open an explorer window and then choose from the menu Tools -> Folder Options -> View -> and then UNCHECK "Hide extensions for know file types". The typical extensions that can be infected or may be spyware etc. will end in .exe (EXEecutable program), .bat (BATch file), .com (COMmand), .dll (Dynamic Link Library), .vbs (Visual Basic Script), .scr (SCReen saver), .sys (SYStem driver). If you are downloading, installing, or receiving one of these as an attachment then be especially careful. Also files which end in .zip or .rar are special cases because they are Archives (compressed collections of other files) which may contain any of the above types.

OK so now PREVENTION.

Some of the most common ways of being infected are:
  • downloading and installing software when you don't know if it is clean - scan it first!!
  • opening an email attachment which turns out to be a virus etc.
  • clicking on a internet popup window that says your computer is infected!
  • mistakenly installing "fake" antivirus software eg antivirus pro
  • increasingly more common - "drive by infections" - you visit a site which runs a script to infect your machine.

To prevent this happening:
  • have antivirus and antispyware software installed on your computer, keep it up to date and scan your system regularly. All of the school machines should have CA Trust antivirus installed (see below).
    But if you don't have antivirus / antispyware installed, then some of the better free ones are: AVG , AVIRA for antivirus and Spybot for anti-spyware.
  • don't open email attachments from people you don't know
  • don't install software unless you know it is clean AND
  • If you download installable software, use a well-known, reputable site as your source, not some website you've never heard of before
  • scan any usb or thumb drives (especially those that aren't yours!) before you use them
  • don't open email attachments that end in the above types unless you know what they are. Better yet scan them before opening them. And beware of email spoofing (where an email looks like it comes from someone you know), but it doesn't really.
  • better yet - use web-based email (like gmail, hotmail etc.)
  • files of type JPG, MP3, MPG (pictures, music, movies) are generally a bit safer (harder to infect).

Other important things to know:
  • Realize that because any anti-virus software is not 100% effective, you cannot rely on it entirely and must always exercise caution, even if it says everything is okay
  • To minimise the impact of a virus attack, regularly back up all your important data to storage outside your computer (for example; documents, pictures etc.)

And last CURE.

So you think you have a Virus or you think an attachment may contain a virus. First scan your machine or the file.
Nelson Central School uses CA Trust which is the green (or blue) box with a heartbeat symbol on the bottom right of your taskbar. Screen02_Aug._12_12.11.jpg
It provides both Virus and Spyware scanning. You can scan files using CA Trust by choosing (from an explorer window) what you want to scan, then right clicking on it, choosing Scan for Viruses and then pressing the Green play button. You can scan individual items or whole drive (like a USB drive) this way. If a virus is found it will report it like this Screen03_Aug._12_12.21.jpg

Alternately, Jotti is an online site to which you can upload files you think might be infected and have them checked by multiple virus software programs - because surprisingly, not all viruses are picked up by any one program.

Screen01_Aug._12_11.48.jpg

Antivirus software (like CA Trust) will attempt to disinfect and / or quarantine infected files - which stops them harming your computer further, but Jotti will only tell you about whether a file is infected - it won't cure it! You need to run a complete local virus scan until your system passes as clean.

Some other useful sites:

From netsecurity.about.com Protect Yourself from Spyware


and from the same, Don't Close that Pop-up Window