NeverLAN CTF 2_2020

Github

Reverse Engineering

Description: This program seems to get stuck while running... Can you get it to continue past the broken function?

• Quickly, I ran script under IDA, saw a broken is SIGSEGV.

• This error exist went script accessed in unexisted address.
• After 2 hour attempt to pass an error by editting value and findding an address. I got hint from my friend: "read the description carefully".
• Ah sh!t, I don't have to pass the error if i don't get the error.
• Then, i read the script line by line and saw the strange function.

• Set breakpoint and use F2 to editting '0 -> 7A' in hex, i got access in print and saw the flag.

adobe payroll

Description: We've forgotten the password to our payroll machine. Can you extract it?

• Knowing this is a .NET exe, i use dnSpy to decrypt

• As I saw, if checkUsername() and checkPassword() is true, I got stringBuilder, it's flag.

• Not thing to do more.

DasPrime

Description: fix and find the 10,497th prime number

• Actually, I just search the 10,497th prime number.
• This is the correct script:

Password_crack

Description:

• I found all the name of this ctf author and basic color, changed the password to md5 and compare with given information.

• pass: orange-1984-zestyfe

pigsfly

• Use Piggen Cape Cipher to decode.

It is like an onion of secrets

Discription:

• First thought went I saw that pic is steganography, i used online tool to decode and had Base64 code, decode Base64 twice and got message:

• Next, use Vigenère to get flag.

Open backpack

• Just change the file name extension to .zip and get the flag.

PCAP

• For all challenge: Just open all file and find the flag.
• This is a script to find flag.