CTF Write-up : RESTCON{}

3 min readAug 29, 2020

Recently i participated in RESTCON CTF (28–08–2020). It was really good CTF. here is my way to solve different challenges.

BASIC

1. BASIC 1

At first look we can see that Flag is in front of us. So i tried to find different possible combination but after few minutes i figure out that we just need to reverse of the string.

Flag : RESTCON{RESTCON_FLAG}

2. BASIC 2

At first look we can see it’s Base64 string. so decoded it with Base64 and yes i found 2nd flag.

Flag : RESTCON{RESTCON_2ND_BASIC_FLAG}

3. BASIC 3

Chal File contain following string in it.

;FOM`6VgI(;FOM`6VgHa5u(3T84?E`6:”OA6XN;V5t?>

At first look it was hard to detect which encoding scheme is this. After few google search i found this is Base85 string.

Flag: RESTCON{RESTCON_ANOTHER_BASIC_FLAG}

4. Broken

As we can see image is not showing. So i tried inspect element and yupp i found another flag.

Flag : RESTCON{H1DD3N}

5. Garbage

We have one text file.

So i thought let me open it in HEX editor.

Yaas we found flag at end of file.

Flag: RESTCON{GR3P_7HE_FL4G}

It contain following thing in file

At first look i was like what is this!!!!!

After few google search i found that this is “Malbolge Language”. So i used following website to decode it. http://www.malbolge.doleczek.pl

Flag : RESTCON{Malb0lg3_is_cool}

Debugging

We got one python program.

We got some python program. So i try to execute it.

We got error “argument of type ‘type’ is not iterable.

So i started to do debugging. we got error at line 20 so i thought let me comment out that particular peace of code. and added one line print(character)