Re,
>...
>If you want some indepth on polymorphis I recomend you the 29a papers:
>http://vx.netlux.org/29a/
I'm not a master in this branch however let me citate one of the
aritcles found on the server you sent me (i also recomend you to read it):
----- CUT --------------------------------------------------------------
" There exists a system of division of polymorphic viruses into levels
according to complexity of code in decryptors of those viruses. Such a
system was introduced by Dr. Alan Solomon and then enhanced by Vesselin
Bontchev.
Level 1: Viruses having a set of decryptors with constant code,
choosing one while infecting. Such viruses are called "semi-polymorphic"
or "oligomor phic".
Examples: "Cheeba", "Slovakia", "Whale".
Level 2: Virus decryptor contains one or several constant
instructions, the rest of it is changeable.
Level 3: decryptor contains unused functions - "junk" like NOP,
CLI, STI,etc
Level 4: decryptor uses interchangeable instructions and changes
their order (instructions mixing). Decryption algorithm remains unchanged.
Level 5: all the above mentioned techniques are used, decryption
algorithm is changeable, repeated encryption of virus code and even
partial encryption of the decryptor code is possible. "
----- CUT --------------------------------------------------------------
So appending to this source i got a level 3 or level 4, unless you fully
understand the source. I'm not saying it is perfect, is was written in 5
days.
Hope this helps you.
best regards,
Piotr Bania
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