Comment 0 for bug 578922

Binary package hint: apparmor

I have reported this to the CERT/Bugtraq system so you may have been contacted by them. It was a large bug report so something may have fallen though the cracks.

The problem is AppArmor rule sets do not antiquity protect a LAMP environment from attacks. Exploit code has been written which bypasses AppAmoror rule sets to obtain remote code execution. The exploit can be obtained here (https://sitewat.ch/Exploits/nuke_exploit.txt).

The attack scenario:
Back before AppArmor it was common to see sql injection attacks against PHP/MySQL like this:
Vulnerable code:
<?php
mysql_query("select name from user where id=".$_GET[id]);
?>
Exploit:
http://localhost/sql_inj.php?id=0 union select "<?php eval($_GET[e]);?>" into outfile "/var/www/backdoor.php"

AppArmor stops this attack, which is impressive. However, there is a flaw in this security system. In my exploit i am dropping the file in "/tmp/theme.php" then i use a Local File Include vulnerability (LFI) to execute this php file. The problem is that BOTH MySQL and Apache have access to /tmp/. The line "#include <abstractions/user-tmp>" in the usr.sbin.mysqld is the source of the vulnerability. The patch is very simple, mysql should have its own tmp folder that only the mysqld process has access to.

This whole concept of process separation to prevent attacks is completely undermined by creating "unions" between processes in the form of these header files. In fact every time you see an #include in an app armor rule set, its a point of weakness. I hope to give a another killer blackhat/defcon talk, this time i am talking about about my exploit and these abuses against apparmor.

Thanks,
Michael Brooks.