Most of you already use an antivirus solution but do you really know what it does and what makes a solution better than another one?

I'll try to spot some very important points to make your choice.

Antivirus works in two different ways:

-Static Mode
 
     AV is active upon user request/action
 
-Dynamic Mode:

     AV is always active(resident software) and performs action without any user interaction.
 
Antivirus Technics:

1. Shape analysis
   
   This solution relies on analyzing a file content out of an execution context.
   Unfortunately this is an unsolvable problem, and this is not a very accurate solution.
2. Databases/Signatures
   
   The goal of this, is to find out a/some revelant bits coming from a well known virus.
   But this solution relies on a database and it's an utopy to think that every virii can be identify.
   On the other hand this solution does not allow polymorphic detection, and suppose that you keep your software up to date with the very last virus definition.
3. Spectrum Analysis
   
   Beyond this cryptic name, Spectrum Analysis looks for running instructions and try to found out any non common instructions that may be due to virus
   
   
4. Heuristics
   
   Heuristics is a math model applied to computer industry.
   The hidden goal of this is to detect potential harmful threat by assigning a score to it.
   This as well as spectrum analysis has a limited scope and can generate some false-positive.
5. Integrity checks
   
   Or how to use a sandbox.
   When installing your antivirus it will assign a checksum to executables or files you trust.
   If a threat, malware or virus try to modify those trusted files, your software will automatically detect it because the checksum will be different.

 Most of current anti-virus use a mix of all those technics to have the better detection ratio they can.

 

 Hereunder a choice of pretty good antivirus software:
 
Avast -> http://www.avast.com
AVG -> http://www.grisoft.com
Kaspersky -> http://www.kaspersky.com
NOD32 -> http://www.nod32.com
     
 
Hope this article will help you to understand a bit more how your antivirus works.

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