Linux Privilege Escalation Write-ups Guides & Notes

  1. https://blog.g0tmi1k.com/2011/08/basic-linux-privilege-escalation/

  2. https://www.securitysift.com/download/linuxprivchecker.py

  3. http://pentestmonkey.net/tools/audit/unix-privesc-check

  4. http://www.darknet.org.uk/2015/06/unix-privesc-check-unixlinux-user-privilege-escalation-scanner/

  5. https://www.youtube.com/watch?v=dk2wsyFiosg

  6. http://resources.infosecinstitute.com/privilege-escalation-linux-live-examples/\#gref

  7. https://www.rebootuser.com/?p=1758

  8. http://blog.g0tmi1k.com/2011/08/basic-linux-privilege-escalation/

Linux Privilege Escalation Check

  1. https://github.com/reider-roque/linpostexp -- All in one checker

  2. http://www.rebootuser.com/?p=1758

  3. https://github.com/1N3/PrivEsc/tree/master/windows

  4. http://www.securitysift.com/download/linuxprivchecker.py

  5. https://gist.github.com/1N3/376f17d87b2da190ca5f31e880bd6c08

  6. https://github.com/rebootuser/LinEnum -- MY FAVOURITE

  7. https://github.com/s0nk3y/php-kernel-exploit/ very good

Linux Privilege Escalation - Tools

  1. https://github.com/ngalongc/AutoLocalPrivilegeEscalation

  2. https://github.com/PenturaLabs/Linux\_Exploit\_Suggester

  3. https://github.com/mzet-/linux-exploit-suggester

  4. https://github.com/spencerdodd/kernelpop --- Automated unix Privilege excalation framework

  5. https://github.com/m4lv0id/LARE

  6. https://github.com/semyon-san/getsploits

  7. https://github.com/SecWiki/linux-kernel-exploits

  8. https://github.com/b3rito/yodo -- Automated

Introduction

Privilege escalation is driven by information gathering.

Straight-forward vectors include vulnerable kernels, vulnerable services running as root and setuid programs, but often escalation is achieved through the manipulation of file permissions, paths and other subtle mis-configurations.

Methodology

  1. Information Gathering
  2. Process
  3. Exploit
  4. Repeat - (extensive trial and error is often required)

Information Gathering

Operating System Enumeration

The distribution and kernel versions will be key pieces of information in attempting to locate a viable local privilege escalation attack. Often a particular kernel version or linux distribution will be vulnerable to a well known specific exploit or avenue for privilege escalation.

Determine linux distribution and version

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

Applications and Services Enumeration

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/
yum list | grep installed
Solaris: pkginfo
Arch Linux: pacman -Q

Determine versions of important applications

gcc -v
mysql --version
java -version
python --version
ruby -v
perl -v

Review installed configurations

Syslog Configuration

cat /etc/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 Configuration

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

Communications and Networking Enumeration

Identify connected NICs and other networks

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

Identify connected users and hosts

lsof -nPi
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 -n
/sbin/route -nee
ip ro show

Identify network configuration Settings (DHCP, DNS, Gateway)

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

User and Confidential Information Enumeration

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

**Dump all Local, LDAP, NIS, etc password hashes

getent passwd

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 mail aliases or all aliases

cat /etc/aliases
getent aliases

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

File System Enumeration

The following commands are helpful when looking to exploit local applications for privilege escalation

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

Exploitation

##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

One method to overcome library dependency problems is to compile the exploit statically locally and upload. The trade-off is that the file will be quite large.

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