Differences                   (Rev #3    vs    2):
<p>To avoid being detected by emulation? some    |  To avoid being detected by emulation? some vi
 <strong>viruses</strong> rewrite themselves     |  ruses rewrite themselves completely each time
completely each time they are to infect new e    |   they are to infect new executables. Viruses 
xecutables. <strong>Viruses</strong> that use    |  that use this technique are said to be metamo
 this technique are said to be metamorphic. T    |  rphic. To enable metamorphism? a metamorphic 
o enable <em>metamorphism</em>? a <em>metamor    |  engine is needed. A metamorphic virus is usua
phic engine</em> is needed. A <em>metamorphic    |  lly very large and complex. For example? W32/
 virus</em> is usually very large and complex    |  Simile consisted of over 14000 lines of assem
. For example? <strong>W32/Simile</strong> co    |  bly code? 90% of it part of the metamorphic e
nsisted of over 14000 lines of assembly code?    |  ngine.
 90% of it part of the <em>metamorphic engine    <
</em>.</p>                                       <