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Friday, July 15, 2011

Tips for computer security and to prevent viruses

 

You must run quality security software on your computers to protect your work and private data from viruses, spyware, and other security threats. When it comes to security, there is no substitute for quality. See below our recommended quality solutions. If any of the following is difficult for you, get an IT Expert to do it for you. You must do the following or risk all of your work/data being compromised (think of it as locking your front door):

  1. Get good anti virus software e.g. one of the below.
    Recommended anti virus software:
    - AVG - Our most recommended Antiv Virus software.
    - Norton Anti virus
    - McAffee Anti Virus
    - Sophos Anti Virus

    Be sure to regularly update your 'virus definitions' e.g. once per week
  2. Install a quality Firewall
    There are many firewalls available, some good, some bad. Our recommendation is the FREE ZoneAlarm. They provide a paid version with extra tools (of course), but we think the free firewall-only option is fine. Its getting harder on their site to see the free one (so look carefully!). At time of writing, go here, scroll down and click the free option. If the above link doesn't work, start looking from the Zone Alarm front page.
  3. Install an anti-spyware application
    There are many available, some good, some bad. Our recommendation is the FREE: Spybot - Search & Destroy. Download here, and find Spybot info here.
  4. Email Attachments: BEWARE OF ATTACHMENTS. Do not open email attachments you are not expecting. Viruses come with some very nasty messages to trick you into opening the attachement e.g. "Your email account has been cancelled, see attachment for details". Even worse, the virus looks like it comes from an email address you recognise e.g. from admin@yourDomain.com (where 'your domain' is the domain name that you use). Virus attachments can have the following 'file extension': .exe, .pif. If you receive a .zip attachment and open it - make sure it doesn't contain a file with one of those extensions. Do not open attachments you haven't requested, even if they appear to be from people you know.

Why do I receive, notices that emails from me could not be delivered - when I didn't send the email?

  • How did someone else send an email that looked like it was from me?
  • Why do such emails seem to be from someone who is not in my organisation?
This is usually caused by a virus on someone elses computer sending the emails, but making it look like the emails are from you, or to put it another way: A virus that spoofs the 'from address'. The important (and annoying) thing to note is that the virus is probably not on your computer, it is on someone elses. So even if you have quality anti-virus software that keeps your computer clean, there is someone else out there who's computer is infected and sending these emails out.

How viruses spoof the from-address in emails

  • You have effective anti-virus software, so your computer is clean,
  • You send an email to Fred,
  • Now your email address is in Freds address book in his email software,
  • Fred does not have effective anti-virus software, and his computer has a virus,
  • The virus on Freds computer scans his address book for all of the email addresses on it,
  • The virus sends email to every address on Freds address book,
  • The virus emails do not say they are from Fred!, The virus pics another addresse from Fred's address book and puts it in the 'From field' in the outgoing email. The virus may combine the name from one address and the domain from another, creating a 'from address' that does not exist.
  • These emails are received by other computers, which detect the virus (because they have good anti virus software) and reject the email,
  • When the receiving computer rejects the virused email it sends an 'Undeliverable' to the sender e.g. something like 'Subject: /Delivery Notification: Delivery has failed'.
  • But! the 'Undeliverable' note goes to the spoofed from address (not to Fred) e.g. the 'Undeliverable' note could be sent to you.
  • Often there is no trace of Freds real address in the virus email or the 'Undeliverable' note, so you can not tell who's infected computer is sending these emails.
The solution: Make sure you have good anti-virus software and tell everyone you know to do the same.

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