Level
medium
Type
Misc
Trapped inside this shell .... your commands are locked tight .... Can you break free from the jail .... and find the hidden light?
connect: nc < ip_address > < port >
example: nc 192.168.1.10 4444
nc xxx.xxx.xxx.xxx 9876
sam: Uh oh... Im FFFFF... cant think straight!
azz: Shiiiiiuuuuuuush... relax, just run the commands here at Brainer.
sam: Wait, really? This is where I reboot and level up?
azz: Exactly! When your brains stuck
sam: time to run and conquer!
/ [BF]$- Connects to challenge service at port 9876
- trying to execute any command won't work, BUT The question includes strings related to
Brainfuck(FFFFF,Brainerand,brains) the shell prompt indicatorBF, which are clearly connected toBrainfuck. - Decodes
cd ../directory name: nothing new - Confirms directory
cd ../../../again: nothing new - Decodes
lscommand: see homedir - Decodes
cd homedirectory: seeEcho dir - Decode
cd Echo: - Decode
ls: seeREADME.txtandstuff dir - Decodes
cat README.txtfile: seeDecode the chaos, navigate the loops, and reveal the treasure buried in the code. - Decode command
cd stuff: seeNeuroNexus - Decode
cd NeuroNexusfile in/home/Echo/stuff/NeuroNexus: seeAlertFlag.txt - We will check each folder by displaying the flag with cat, and if it’s fake, move to the next folder using
cd ../until we find the correct flag (each step we decoded) - Decodes fake
flag1:/NeuroNexus/AlertFlag.txt: seeYUCTF{Dummy_fake_flag_123_Dummy_fake_flag_123} - Decodes fake
flag2:/MindMatrix/AlertFlag.txt: seeYUCTF{Not_the_real_flag_456_Not_the_real_flag_456} - Decodes
real flag:/BrainFuel/.hidden/AlertFlag.txtseeYUCTF{Ghost_in_the_shell_Ghost_in_the_shell} - Decodes exit command : see Final message
GoodbyeGoodbyeGoodbye. - Flag:
YUCTF{Ghost_in_the_shell_Ghost_in_the_shell}
nc ipaddress 6969++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.++++++++++++++..+.++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.++++++++++++++..+.-..+.-..+. ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>++++++++.+++++++.++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.>>++++.+++++++.--.--------.++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.>-.>-.+++++.+++++++.++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>++++++++.+++++++.++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.--.+++++++++++++++++++.<<++.>++++++++++++.-------------.----.+++.+++++++++.--------.<++++++++++++++.>>.++++.----.++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.>>+++++++++++++++.+.+.---------------..++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.>++++++++.>+.++++++++++++++++.---.---.<.>----------.+++++++++++++++++++.---.--.++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.--.+++++++++++++++++++.<<++.>-----.>--------.-------.+++++++++++++.++.<+++++.>--------.-----------.++++++.<<++++++++++++++.>>+++++++++++++.++++.----.++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.--.+++++++++++++++++++.<<++.>.>--------.-----------.++++++++++++++++++.-----------.<++++++.>+++++++.--------.++++++++++++.<<++++++++++++++.>>+.++++.----.++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.--.+++++++++++++++++++.<<++.>-----.>--------.-------.+++++++++++++.++.<+++++.>--------.-----------.++++++.<<++++++++++++++.>>+++++++++++++.++++.----.++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>+.+++++++++++++++++++.---------------.+++++++++++. ┌──(semopurple㉿SemoPurple)-[~/Desktop/YUCTFv1/YUMISC/Bashcape]
└─$ nc xxx.xxx.xxx.xxx 9876
sam: Uh oh... Im FFFFF... cant think straight!
azz: Shiiiiiuuuuuuush... relax, just run the commands here at Brainer.
sam: Wait, really? This is where I reboot and level up?
azz: Exactly! When your brains stuck
sam: time to run and conquer!
/ [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>++++++++.+++++++.
home
/ [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.>>++++.+++++++.--.--------.
/home [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.>-.>-.+++++.+++++++.
/home/Echo [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>++++++++.+++++++.
README.txt
stuff
/home/Echo [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.--.+++++++++++++++++++.<<++.>++++++++++++.-------------.----.+++.+++++++++.--------.<++++++++++++++.>>.++++.----.
Decode the chaos, navigate the loops, and reveal the treasure buried in the code.
/home/Echo [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.>>+++++++++++++++.+.+.---------------..
/home/Echo/stuff [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>++++++++.+++++++.
NeuroNexus
MindMatrix
BrainFuel
/home/Echo/stuff [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.>++++++++.>+.++++++++++++++++.---.---.<.>----------.+++++++++++++++++++.---.--.
/home/Echo/stuff/NeuroNexus [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.--.+++++++++++++++++++.<<++.>-----.>--------.-------.+++++++++++++.++.<+++++.>--------.-----------.++++++.<<++++++++++++++.>>+++++++++++++.++++.----.
YUCTF{Dummy_fake_flag_123_Dummy_fake_flag_123}
/home/Echo/stuff/NeuroNexus [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.++++++++++++++..
/home/Echo/stuff [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.>----.>++++++++++++++.-----------------.++++++++.+++++.<++++.>+++++++.----------------.+++++++.
/home/Echo/stuff/BrainFuel [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>++++++++.+++++++.
.hidden
/home/Echo/stuff/BrainFuel [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.+.<<++.++++++++++++++.>>++++.+.-----..+.+++++++++.
/home/Echo/stuff/BrainFuel/.hidden [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>++++++++.+++++++.
AlertFlag.txt
/home/Echo/stuff/BrainFuel/.hidden [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>-.--.+++++++++++++++++++.<<++.>-----.>--------.-------.+++++++++++++.++.<+++++.>--------.-----------.++++++.<<++++++++++++++.>>+++++++++++++.++++.----.
YUCTF{Ghost_in_the_shell_Ghost_in_the_shell}
/home/Echo/stuff/BrainFuel/.hidden [BF]$ ++++++++++[>+>+++>+++++++>++++++++++<<<<-]>>>>+.+++++++++++++++++++.---------------.+++++++++++.
GoodbyeGoodbyeGoodbye.