mauke

I thought it might be fun to write a "polymorphic virus", but that would involve learning executable file formats and machine code, which sounds like a lot of effort. So instead I went for the next best thing: Perl instead of machine code, and self-replicating code in the form of a quine rather than "infecting" other executables.

When you run this code, it will output a new version of itself, which you can run again to get another version, etc. Unlike a regular quine, which will produce an exact copy of its source code, this program is polymorphic: Its output is functionally identical to the original, but the code might look completely different. This is just a proof-of-concept, but it does try to introduce variations in all parts that a simple static scanner might use for detection (such as signatures in an antivirus). There are still fixed parts, but they're small and generic (such as ; or =) and can be found in most any perl script.

(my $Edw70Kp = "|ygn`hjs\nmo\\yjc]eyuy}YUl[h^y:YWyw\nmo\\ym`gnyu\nyyyygsy\"}mnl#y7y:Y5\nyyyyl_nolhymjlchn`\"{p~p^{&y}mnl#\nyyyyyyyyc`yl[h^\"#y6y*(,5\nyyyy}mnly7xymu\"UXy'xW#v\"U{V}V:VVW#wu\nyyyyyyyy^_`ch_^y},y9y{VV},{y4\nyyyyyyyy}+y_ky{Vh{y9y{VVh{y4\nyyyyyyyymjlchn`\"{VVr~*,r{&yil^y}+#\nyyyyw_a5\nyyyy!{!y(y}mnly(y!{!\nw\n\ngsy}p[ly7y!}!y(ydichy!!&yjc]e\"![!y((y!t!&y!;!y((y!T!&y!Y!#&yg[jyjc]e\"![!y((y!t!&y!;!y((y!T!&y!Y!&y!*!y((y!3!#&y'-y((yl[h^y++5\ngsy\"}ip[l#y7y}?^q1*Ejy7xy)7yV}\"Vq%#y7)5\n}?^q1*Ejy7xym)V}}ip[lV\\)}p[l)a5\n\ngsy}h_rny7yjc]e\"!!&y!gsy!&y!ioly!#y(y}p[ly(y!y!y(yjc]e\"!7!&y!(7!&y!vv7!#y(y!y!5\n\nc`y\"l[h^\"#y6y*(/#yu\nyyyygsy}ey7ydichy!!&yg[jyuy]blyl[h^y,/0ywy+y((yf_hanb\"}?^q1*Ej#5\nyyyy}h_rny(7ym`gn\"}e#y(y!yXy!y(ym`gn\"}eyXy}?^q1*Ej#5\nwy_fm_yu\nyyyygsy}lmy7yil^y{y{5\nyyyygsy}l_y7yil^y{x{5\nyyyygsy}lqy7y}l_y'y}lm5\nyyyygsy}^y7y+y%ychnyl[h^\"}lq#5\nyyyy\"gsy}^j_`y7y}?^q1*Ej#y7xym)\"Uy'xW#)]bl\"\"il^\"}+#y'y}lmy%y}lqy%y+y'y}^#y~y\"}lqy%y+#y%y}lm#)_a5\nyyyy}h_rny(7ym`gn\"}^j_`#5\nyyyygsy}hy7y]bl\"}lmy%y}^#5\nyyyy\"gsy}gy7y}h#y7xynl)z'xy)y'x)5\nyyyym)\"UV)V'VVW#)VV}+)ay`ily}g&y}h5\nyyyy}h_rny7y{\"}h_rn#y7xy{y(yjc]e\"!nl!&y!s!#y(y{)y'x)}h'xy'}g){5\nw\n}h_rny(7y!5y!5\n\n}h_rny(7yjc]e\"{_p[fy}p[l{&y{m)X)}p[l)__{#y(y{Vh{5\n\njlchny}h_rn5\n") =~ tr/ -~/&-~ -%/; eval $Edw70Kp