what is the smallest virus size

Just wondering whether anyone can tell me how small in bytes a virus can be? Is there any generally accepted minimum level, so that any unknown files of less than that can be considered safe ?
I am asking because I received an alert from mailwasher of a possible virus. I am pretty sure it's a false alert and NOD does not show any concerns. The attachments are only between 151 bytes and 900 bytes.

 

hi! 151-900 bytes are enough for an virus (com file). the smallest virus i have was 13 bytes - the smallest nod32 could identify from my collection was 128 bytes (material).

 

Interesting - thanks for that

 

Functional threats in attachments must be much larger - the old COM viruses could not propagate via email ;-)

 

Smalest virus is 4 bytes long

 

Yep It's a DOS trojan
One of the most complex Trojan who was ever written

F0|0F|C7|C8 <--- thats it (Doesn't do any harm to newer cpu's and does only lock some special older cpu types)

Note: Thats only the Hexcode, so no danger by reading this post

 

forgot that old F00F pentium bug

 

err... just wanted to constructively reply "Lets Wait for Happy Bytes aka Cool Daddy" when I spotted his post... This reminded me though... I never took the time to read anything about the F00F bug, but always wanted to Now's the time!

 

I was thinking of something like:

8B DE CD 26 or B7 01 CD 26 or 87 DE CD 26 or 87 F3 CD 26 or 56 B5 CD 26 or FE C7 CD 26

 

Refresh your memory here