Challenge Author: LT ‘SYREAL’ JONES

Category: General Skills

Difficulty: Easy

Description

Can you crack the password to get the flag? Download the password checker here and you’ll need the encrypted flag in the same directory too.

Process / Notes

1. wget the password checker and encrypted flag
2. cat both
3. In the decoder program it looks like if the password id 4 specific Unicode characters, you’ll pass and be able to decode the flag
4. The characters are 0x33 0x39 0x63 0x65
5. Or is this hex?
6. It looks like there’s an ASCII conversion

Selection of a Conversion Table
Hex	Decimal	ASCII
0x33	51	3
0x39	57	9
0x63	99	c
0x65	101	e

7. Running the program and trying the password ‘39ce’
8. The flag is revealed!
9. I figured it could be solved on the command line rather than with a table with $ echo '0x33 0x39 0x63 0x65' | xxd -rp

13 minutes 10 seconds to complete

Hints

1. Does the encoding look familiar?
2. The str_xor function does not need to be reverse-engineered for this challenge

Core Lessons

1. Recognize the encoding pattern
2. Understand how to convert the encoded text into plain text