Malicious(?) PHP / BASH Script. What is it?

Question

I'm not sure if this is against the rules of the site. If it is, please let me know and I'll delete the question.

I've seen variations of this script floating around recently. What the heck is it, and what does it do? http://pastebin.com/1XcMTsiL

You can see a list of sites that have been hit with it here: (For the love of god, DON'T click these links unless sandboxed).

https://www.google.com/#q=%22**+*++Use+this+function+for+update+scripts+*++the+output+of+Update%28%29+*%2F+function+Update%28%29%22&hl=en&prmd=imvns&filter=0&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.,cf.osb&fp=bb242dc4ab43ba95&biw=1920&bih=1043

There is a discussion here as well: http://www.webhostingtalk.com/showthread.php?t=1033395

Answer 1

It looks like a set of different malicious things to do when a system is compromised. The script is no more dangerous than the security issue that allowed it to be inserted in the first place. Consider it to be a remote controlling toolkit once the hacker got in.

Once installed it can rewrite itself or other files on the server to be this script, modified to it's current environment. Then tricks the visitor that triggered this script to be redirected to a different website. This script could be used for defacing or (considering it contains stats tracking) trying to generate income by tricking the user into viewing or opening ads and possibly more uses.