picoCTF - General Skills - Hello, friend.

Obedient Cat

We will start with the first task which should not be to difficult ;).

cat flag

Python Wrangling

Download all 3 files what are necessary for the challenge and follow the syntax:

Wave a flag

./warm -h

Nice netcat…

In your terminal call nc mercury.picoctf.net 35652 > nice_netcat. Now with a little python script we will read the output, trim the white spaces, newlines and convert it into ASCII character.

temp = open('nice_netcat')
temp = temp.read().splitlines()
flag = ''

print(temp)
for e in temp:
    flag += chr(int(e))

print(flag)

Static ain’t always noise

Download the static binary and use the following command

strings static | grep pico

Tab, Tab, Attack

Straight forward

Magikarp Ground Mission

Lets Warm Up

0x70 Hex in ASCII – lets see the man files for ascii with – man ascii

Warmed Up

This can be solved with python

>>> int('0x3D', 16)

2Warm

Again python

>>> bin(42)

what’s a net cat?

nc jupiter.challenges.picoctf.org 25103

strings it

strings strings | grep pico

Bases

echo "bDNhcm5fdGgzX3IwcDM1" | base64 -d

First Grep

cat file | grep pico

Based

This can be done with CyberChef open in a separate window

plumbing

nc jupiter.challenges.picoctf.org 14291 > plumbing; cat plumbing | grep pico

mus1c

After a while you will recognize some words which are repeating over and over again. These are shout, put and knock. Just go to google with there 3 words and put on your search a esoteric behind you fill find the first search result very interesting – rockstar.

Just translate the decimal output into ASCII characters and you have the flag which to submit in the format picoCTF{}.

flag_shop

When you look into the source code you will see the part which we can exploit:

This integer can hold 4 Byte – a maximum value of -2 147 483 648 and 2 147 483 647.

To create the complement of the integer we can divide the maximum value of the integer through 899 (not 900 – because of the account balance) and give the result 2388747 as input to the flag volume. After this you can but the 1337 flag.