How to "decode" some obfuscated JavaScript in HTML?

DocWiki picture DocWiki · Nov 11, 2011 · Viewed 11.6k times · Source

Here is one example:

eval(function(p,a,c,k,e,d){e=function(c){return(c<a?'':e(parseInt(c/a)))+((c=c%a)>35?String.fromCharCode(c+29):c.toString(36))};if(!''.replace(/^/,String)){while(c--){d[e(c)]=k[c]||e(c)}k=[function(e){return d[e]}];e=function(){return'\\w+'};c=1};while(c--){if(k[c]){p=p.replace(new RegExp('\\b'+e(c)+'\\b','g'),k[c])}}return p}('4.h={H:9(d){T 7.F(9(){g 1=7;1.3={8:4(d.8,7),i:4(d.i,7),m:4.z.J(7),5:d.5,t:d.t,j:d.j,K:d.K,b:d.b,A:d.A};4.h.s(1,0);4(S).v(\'W\',9(){1.3.m=4.z.J(1);4.h.s(1,0);4.h.E(1)});4.h.E(1);1.3.8.v(\'O\',9(){4(1.3.t,7).l(0).a.I=\'P\'}).v(\'R\',9(){4(1.3.t,7).l(0).a.I=\'11\'});4(Z).v(\'10\',9(e){g p=4.z.Y(e);g c=0;k(1.3.b&&1.3.b==\'L\')g r=p.x-1.3.m.x-(1.w-1.3.5*1.3.8.n())/2-1.3.5/2;u k(1.3.b&&1.3.b==\'N\')g r=p.x-1.3.m.x-1.w+1.3.5*1.3.8.n();u g r=p.x-1.3.m.x;g M=B.G(p.y-1.3.m.y-1.X/2,2);1.3.8.F(9(q){6=B.Q(B.G(r-q*1.3.5,2)+M);6-=1.3.5/2;6=6<0?0:6;6=6>1.3.j?1.3.j:6;6=1.3.j-6;C=1.3.A*6/1.3.j;7.a.D=1.3.5+C+\'f\';7.a.o=1.3.5*q+c+\'f\';c+=C});4.h.s(1,c)})})},s:9(1,c){k(1.3.b)k(1.3.b==\'L\')1.3.i.l(0).a.o=(1.w-1.3.5*1.3.8.n())/2-c/2+\'f\';u k(1.3.b==\'o\')1.3.i.l(0).a.o=-c/1.3.8.n()+\'f\';u k(1.3.b==\'N\')1.3.i.l(0).a.o=(1.w-1.3.5*1.3.8.n())-c/2+\'f\';1.3.i.l(0).a.D=1.3.5*1.3.8.n()+c+\'f\'},E:9(1){1.3.8.F(9(q){7.a.D=1.3.5+\'f\';7.a.o=1.3.5*q+\'f\'})}};4.V.U=4.h.H;',62,64,'|el||fisheyeCfg|jQuery|itemWidth|distance|this|items|function|style|halign|toAdd|options||px|var|iFisheye|container|proximity|if|get|pos|size|left|pointer|nr|posx|positionContainer|itemsText|else|bind|offsetWidth|||iUtil|maxWidth|Math|extraWidth|width|positionItems|each|pow|build|display|getPosition|valign|center|posy|right|mouseover|block|sqrt|mouseout|window|return|Fisheye|fn|resize|offsetHeight|getPointer|document|mousemove|none'.split('|'),0,{}))

Obviously, this code is intentionally written to confuse other people. How can I understand it and rewrite it in simple code?

Is there some tool for this job? This is very common in HTML.

Answer

Brad picture Brad · Nov 12, 2011

This is not "encrypted", it is just obfuscated.

Yes, there are tools available to help, but it isn't a perfect process. All of the original variable names and comments and what not are gone, so a tool can't really add that stuff back in. You have to figure out the details yourself, but a tool can make it easier.