N00bs CTF writeup

This CTF challenge is a bit of a point, let's take a look

The homepage looks pretty good.

Level1

The flag can be seen directly F12.

Flag:infosec_flagis_welcome

Level2

"This picture looks broken, can you check it?"

If I had played Linux, it would have been simple. A Curl command will be able to view the content (as sure as Linux Dafa is good). But I am windows, a little trouble? Download down with UE open to see? Don't do that!

Directly right-click is not able to view the source code, then add View-source: Bar. Good.

It looks like base64 encryption ... (I just see the string at the end, I think it's base64 ....) ）

It is base64, it is solved by Firefox's Hackbar plugin.

Flag:infosec_flagis_wearejuststarting

Level3

Have a QR code? Sweep may have a surprise ...

Because there is no cell phone, I chose the online QR code parser. The results of the parsing are:

Often see the detective movie inside See this telegraph code (Morse code), with their own writing a small tool to be done. (Squint Smile)

Flag:infosecflagismorsing

Level4

This intervention HTTP is a hypertext protocol, and then the pop-up window (but I ordered the forbidden popup, why and soft ...) ）

In fact, this is a tip, can be analyzed under the response header, found inside a parameter is very suspicious.

Could it be flag here .... I don't know.. Guess the next. The flags in the previous flag have some sort of rule (which is correctly followed by the format), and are all prefaced with infosec (case insensitive).

So inside the VASBFRP is ciphertext, InfoSec is clear. This derivation is ROT13, which is a common encryption method used in foreign forums.

Action, with the Firefox Hackbar plugin to verify that you know.

Sure enough, the next step is to reverse the introduction of plaintext. The so-called ROT13 actually feels like a kind of Caesar's code (shift 13). My python is starving.

It's no use getting SHFEBQNU=INFOSEC_FLAGIS_WELOVECOOKIES,SHFEBQNU estimates. So Flag:infosec_flagis_welovecookies

Not to be continued ....

N00bs CTF writeup