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I found some shell scripts which were executed by apache after being uploaded to a Wordpress plugin directory (plugin is reputable).

top -c

25821 www-data  20   0 99108 1268  996 S  779  0.1 105:27.72 ../mine.32 --url=http://vibehacks.net/ --userpass=HI:FRIEND

ps -aufx | grep mine.32

www-data 25819  0.0  0.0   2236   540 ?        S    22:01   0:00  |   \_ sh -c nohup ../mine.64 --url=http://vibehacks.net/ --userpass=HI:FRIEND >./mine.log 2>&1; nohup ../mine.32 --url=http://vibehacks.net/ --userpass=HI:FRIEND >./mine.log 2>&1
www-data 25821  490  0.1  99108  1268 ?        Sl   22:01 120:14  |       \_ ../mine.32 --url=http://vibehacks.net/ --userpass=HI:FRIEND
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2 Answers 2

up vote 1 down vote accepted

I assume, though you don't say it, that you've been hacked and are looking for ways to prevent it from happening again.

I don't think you can control what type of file apache will execute in this way, if you have your handlers set up in such a way that they see everything in a directory to be a CGI. If you change your handlers so that only files with a certain extension type are interpreted as CGI executables, the attacker could just change the filename. Linux will interpret any executable pretty much the same way, so as long as it has an ELF header or a shebang at the top, or is otherwise executable, it doesn't really matter what it's called (and apache doesn't need to care either). So, preventing apache from running shell scripts is not easily done (I don't think it's actually possible). Moreover, the real problem was that an attacker was able to put arbitrary files into trusted locations on your box.

What I would suggest you do is determine how this happened. With wordpress plugins, this could be a few ways. For instance, it certainly could have been uploaded using a stolen FTP account, or SSH account. It could also have been uploaded through a rootkit (which is why I rebuild any box which has been popped). However, since it is in wordpress, the most likely scenario is much sillier.

When wordpress is allowed to update itself and its plugins, and install content using its web UI, you open yourself up to this possibility. If anyone gets access to a privileged wordpress account, or spoofs a server from which this content can be downloaded, or just adds their payload to a plugin and waits for you to update, you have been owned. Although wordpress seems to like this feature, I and everyone I know in the infosec field recommend strongly that it be disabled; apache should never have write access to its own webroot, and that is especially true for CGI locations.

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Thank you for the extensive outline of potential issues. I believe you are right, it seems to be the later issue. –  Ryan Schumacher May 6 '13 at 19:18

If you have found the file/scripts in "Wordpress plugin directory" you should grep that from ftp logs or system logs that from which IP address and using which user authentication that has been uploaded,

Then change password of that user and disable these scripts. You can disable these by changing permissions 000 and ownship root.

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