BITS CTF 2017

RE20: Mission improbable

This was a hexdump file. It was an easy challenge.

I used xxd tool to  convert the file back to binary form.

    xxd -r -p MissionImprobable.TEENSY31.hex  out

Then I tried strings command on the out file.

There were only a few strings, so I looked at those, and there I saw a string:

BITCTF{B4d_bad_U5B0

I then just replaced the 0 with a '}'.

That's it, it's the flag.

    BITCTF{B4d_bad_U5B}

RE80: Riskv and Reward

First of all I used the file command.

    riskv_and_reward: ELF 64-bit LSB executable, UCB RISC-V, version 1 (SYSV), statically linked, stripped

The file command says it is in RISC-V arch.

So we need to use an emulator.

I  googled for it and found this:

    

    https://github.com/riscv/riscv-qemu

So I installed it as per the instructions mentioned in it's git repository.

After installing I tried to debug it , and it started to gives me many errors. I tried to fix those and it took a lot of time. Then I thought that I haven't run it till now, so why not give it a try.

I must say, I was shocked, the bin printed out the flag.

I didn't expect a 80 point challenge to be this simple.

The flag was:

    BITSCTF{s0m3_r1sc5_4r3_w0rth_1t}