when I right click on avast icon, i find an option " set/change password" what does avast need a password?
I think it prevents the settings etc. from being changed without the password.
But, some programs may be able to crack the password?
Depends on the strengh of the password or the program I suppose…
Why would a malware try to do so?
There are other (unfortunately effective) ways to destroy avast installation.
Is a password of 21 digits crackable?
Does that mean that avast cannot protect itself?
As I said before, it depends on the strength of the password, just making it longer is not really long enough. A strong password has different things (e.g. UPPER case, lower case, numbers, symbols…)
avast! does have the self-defense module but, as Tech said, there are other ways that malware has comprimised the avast! installation.
but, if the password of 21 characters is made as strong as possible, can it be cracked?
I’m not sure but, I’d imagine that it is possible,although you’d need a LOT of computing resources and/or a LOT of time
So, its practically impossible right?
I’d leave it at:
Practically - yes
Theoretically - no
Not exactly. Means that there are malware running with admin privileges that could destroy any antivirus installation.
Why the villian always clever than the police nowaday ? ???
the police seems much less interested in fighting “internet crimes”… Spending more of their time fighting " real crimes"
I mean Virus makers are far tech advance than the Antivirus makers. 
@Conogo…^^
Possible explanation^^
*Virus makers are antivirus makers themselves^^
-AnimeLover^^
Really :o Is avast! … :-X
avast! has a good reputation through this forum. ;D
Hehehe^^
Im not saying its avast! though^^ ;D
Avast! cant do such a horrible thing^^
Maybe some big antivirus companies are the culprit^^ ;D
-AnimeLover^^