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What the virus threat levels mean

The Microsoft Product Support and Services Security Team assigns a severity rating for viruses, worms, and other technological attacks according to their impact on Microsoft software and customers. The Microsoft Security Response Center uses this three-level severity rating system for Microsoft security bulletins.

A virus, worm, or other threat receives a severity level rating based on whether it has one or more of the listed conditions below.


Severity = Critical

Critical:

  • We have discovered a vulnerability related to Microsoft software that could allow a virus or other malicious program to harm your system or personal files, or steal personal information stored on your computer.
  • An update to fix or protect against the problem may not be available yet.
  • There are two or more known ways for the threat to infect people's computers, or a new (as yet unknown) path of infection is possible.
  • As a result, the risk of the infection spreading quickly from computer to computer is high. We advise you to be extra careful to keep your computer from becoming infected.
  • If your system becomes infected, your machine could quickly spread that infection to other computers (via e-mail or instant messaging or through a local network) without you even knowing it.
  • Important system and personal files on your computer could be irretrievably damaged.
  • Because of this threat, you might not be able to connect to the Internet at all, or important online services or Web sites might become unavailable.

Severity = moderate

Moderate:

  • We've discovered a potential vulnerability related to Microsoft software, which means a risk to users could develop, but has not occurred yet.
  • There are two or fewer known ways for the threat to infect people's computers, or a new (as yet unknown) path of infection is possible.
  • The risk of infection spreading quickly is medium to high. Again, we advise you to be extra careful to keep your computer from becoming infected.
  • We do not have indications that unique data destruction has happened or will happen because of this threat.
  • No significant disruption in local network or Internet service has occurred.

Severity = Low

Low:

  • No vulnerabilities related to Microsoft software have been found.
  • There is only one way known for the infection to spread, and the potential for the infection to find new ways to spread is low.
  • Therefore, the risk of this threat spreading far and wide is relatively low. Of course, we still suggest that you take precautions to keep your computer from becoming infected!
  • There's no sign that unique data destruction has happened or could happen.
  • No significant disruption of local network or Internet service has occurred.




 

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