# Backdoor CTF 2017

## Dead-PNG-2 - ?? \[300 pts] \[Not Solved]

> n00b accidentally found a corrupted zlib/png file, help him to recover the secret code from the file.

{% file src="<https://980792987-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Md9Bzo_DCKomMglV10a%2F-MdYv_NJrviWOajIhPxR%2F-MdYy01ynx4OhDWubRfI%2Fcorrupt.zip?alt=media&token=170f4531-4dcd-4342-b48c-da6110e658a7>" %}
Corrupt
{% endfile %}

Solution:

Flag:

## Complex RSA - Crypto \[200 pts] \[Not Solved]

> n00b heard that single RSA encryption can be cracked sometimes due to bad implementation, so he encrypted the message twice.\
> See if you can break it.

{% file src="<https://980792987-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Md9Bzo_DCKomMglV10a%2F-MdYyF0AMlU-9z4xcteN%2F-MdYypXCXIbH9Mj-5JRx%2FComplex%20RSA%20200.zip?alt=media&token=6b57025b-27b8-4b62-b762-765efec811ae>" %}
Complex RSA
{% endfile %}

Solution

Flag:

## ECB - Steg \[150 pts] \[Not Solved]

> n00b learnt about ECB and has encrypted some images with it.\
> Can you find the flag?

{% file src="<https://980792987-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Md9Bzo_DCKomMglV10a%2F-MdYv_NJrviWOajIhPxR%2F-MdYwnIavp9i0Z6k_jXN%2Fimg1.png?alt=media&token=bd4a9615-0946-4040-930d-8497a35b797e>" %}
img1
{% endfile %}

{% file src="<https://980792987-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Md9Bzo_DCKomMglV10a%2F-MdYv_NJrviWOajIhPxR%2F-MdYwqFPjLbP-kn2db6f%2Fimg2.png?alt=media&token=448adc16-ed2d-4b34-a06e-2f7538b4ba00>" %}
img2
{% endfile %}

Solution

Flag:

## ImageRev - Crypto \[200 pts] \[Not Solved]

> Reverse the encrypted file and recover the flag

{% file src="<https://980792987-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Md9Bzo_DCKomMglV10a%2F-MdYyF0AMlU-9z4xcteN%2F-MdYyxroayZRH8CGnRkE%2FImagerev%20200.zip?alt=media&token=2c21c92e-7a85-4906-ae49-3da4eab8df7c>" %}
Encrypted
{% endfile %}

Solution

Flag:

## NoCalm - Rev \[350 pts] \[Not Solved]

> h3rcul35 and starlord were having a heated conversation and to c00l down the furious starlord, h3rcul35 gave him a binary and said "The binary takes each 'character' byte of the flag as argument. Given this info, grab the flag. I hope you dont get angry :P". \
> Show h3rcul35 that you stayed c00l by finding the flag.

{% file src="<https://980792987-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Md9Bzo_DCKomMglV10a%2F-MdYyF0AMlU-9z4xcteN%2F-MdYz3fbbILA2PpahsPU%2Fchallenge.zip?alt=media&token=c8b813a9-7b21-4f96-b5d5-c1301b22721c>" %}
Challenge
{% endfile %}

Solution

Flag:

## Stereotype - Crypto \[300 pts] \[Not Solved]

> n00b is so sure that no one can crack his message and in this foolishness he even provided a part of plaintext. \
> You know what you have to show him

{% file src="<https://980792987-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Md9Bzo_DCKomMglV10a%2F-MdYyF0AMlU-9z4xcteN%2F-MdYzAAnW-ztXWIh7pc0%2FStereotypes%20300.zip?alt=media&token=ad1cf591-7f80-4c6c-9d7b-95d1769f8768>" %}
Text Files
{% endfile %}

Solution

Flag: