Zeromutarts - Serial verifier

Website :  http://zeromutarts.de/

Question :
Try to validate the nice little piece of code. You will get your flag here: Serial verifier

As i tried on windows i would like to share only windows

File : Windows

Solution : 
Click on Serial verifier link.You would get this

I used ida-pro.
Basic approach : view->open subviews->strings , you would land up something like this :-)

Now double clicking on the string "I would like to know your serial now" ,you would landup to ida-view.switch to graph-view and again go to view->open subviews->pseudocode

Zeromutarts - the magic of rsa

Website : http://zeromutarts.de/

Question :
You were able to hear some whispering on the last crypto party! *whisper* d is 35181901. Keep it secret or we are doomed!

There are 2 files namely rsa.py and rsa.txt,you can download it from here..

the-magic-of-rsa

Answer:

I would suggest to read about RSA here in wiki
RSA_(algorithm)

the parameters we know is n,e and d
oh wait!! what is d? look at the question.. d is 35181901

plain-text = (cipher-text)^d mod n

This is the formula.we know all the parameters.Ciphertext is the one in rsa.txt. I would suggest you to write it in a script because trust me you will learn a lot.

Anyway you could use this website as well :
RSA Calculator

substituting d,n and the ciphertext we would get
flag{you_got_the_basics_my_padawan}

FLAG : you_got_the_basics_my_padawan

Zeromutarts Challenge-5 (encodings)

Website :http://zeromutarts.de/

Question :
I believe a flag is hidden in this encoding. Can you find it?:

TWF5YmUgeW91IHNob3VsZCB0aGluayB0aGUgb3RoZXIgd2F5OiBbKSJ9cmdoZW9faGdfZ3J7dG55cyIgOnJmbnBlcmpieSBhdiB0bnlzIHJ1ZyBnYnQgaGJMIC9iXCAhcnB2QSggOj90aSB0ZmlocyBuZXZlIHVveSBuYWMgLHJhZW4gc2kgZG5FIG5BXQ==

Fine , First thing to observe is "==" in the message ..Its a base-64 encoding is what can be concluded..

Base-64 online tool

we get :
Maybe you should think the other way: [)"}rgheo_hg_gr{tnys" :rfnperjby av tnys rug gbt hbL /b\ !rpvA( :?ti tfihs neve uoy nac ,raen si dnE nA]

After reversing we get : 
An End is near, can you even shift it?: (Avpr! \\b/ Lbh tbg gur synt va ybjrepnfr: "synt{rg_gh_oehgr}")

After shifting 13 times that is 'M' is the key..
we get :
Na raq vf arne, pna lbh rira fuvsg vg? : )Nice! \o/ You got the flag lowercase: "flag{et_tu_brute}")]

Flag : et_tu_brute

Zeromutarts Challenge-4 (chbs)

Website : http://zeromutarts.de/

Question :
Tr0ub4dor&3

Answer :
Looks like trivia question and yes it is  :-)

Google "Tr0ub4dor&3"...

third website says this :
This comic is saying that the password in the top frames "Tr0ub4dor&3" is easier for password cracking software to guess than "correcthorsebatterystaple"

Challenge is chbs and the string is "correcthorsebatterystaple".hence it matches..But remember the format ?

Flag : correct_horse_battery_staple

Zeromutarts Challenge-3 (Caeser's Last Wish)

Website : http://zeromutarts.de/

Question :
Caesar left a message for me. Can you decrypt it?

message :
zh zrxog qhyhu pdnh lw wkdw hdvb.. rxu hqfubswlrq lv rqh vwhs dkhdg!livi mw er mrgvihmfpi xlsyklx sj geiwevr alex ai amwl, ai viehmpc fipmizi, erh alex ai syvwipziw xlmro, ai mqekmri sxlivw xlmro epws. ai amwl xli jpek mw jpek{xairxc_xlvii_wxefw_evi_aec_xss_qerc}

Caeser online tool

Simple caesar decryption would give us a hint :
we would never make it that easy.. our encryption is one step ahead!ifsf jt bo jodsfejcmf uipvhiu pg dbftbso xibu xf xjti, xf sfbejmz cfmjfwf, boe xibu xf pvstfmwft uijol, xf jnbhjof puifst uijol bmtp. xf xjti uif gmbh jt gmbh{uxfouz_uisff_tubct_bsf_xbz_upp_nboz}

Now we need to try Shift Caeser: Lets check from key 1,2,3,4 woajh got it :-)

In the same online tool you see this ?
"Number of letters to shift to the right:" In the box put 4 and click decipher.

We get :
vd vntkc mdudq lzjd hs sgzs dzrx.. ntq dmbqxoshnm hr nmd rsdo zgdzc!here is an incredible thought of caesarn what we wish, we readily believe, and what we ourselves think, we imagine others think also. we wish the flag is flag{twenty_three_stabs_are_way_too_many}

Flag : twenty_three_stabs_are_way_too_many

Zeromutarts Challenge-2 (antonin)

website : http://zeromutarts.de/

Question :
antonin

I got a letter from my friend Antonín. However, it's all Czech to me, maybe you can read it.

Message :
E.ap ipc.bew
C dgoy ,aby yt n.y ötg rbt, yh. o.jp.y itp yh. .bjpözy.e ojptnn C o.by ötgv Go. cy ,co.nö abe et bty uck. cy yt abötb.v

Yh. o.jp.y coV inau{i..n'ot'xth.mcab'ncr.'ötg}


Well now the question is clear so how do we proceed ?
Lets have some google search..Who is antonin? is there a encoding method blah blah..

wiki says that the guy in the picture is antonin dvorak and there is a dvorak encoding..
Antonin Dvorak  Dvorak Encoding

Lets search for a online tool.
dvorak cipher decoder

After we convert it to QWERTY we get this :
Dear griend,
I hust want tk let öku onkw tje secret gkr tje encrö/ted scrkll I sent öku. Use it wiselö and dk nkt five it tk anökne.
Tje secret is> glaf_geelqskqbkjemianqlioeqöku+

So now its easier..so which alphabets is replaced from normal english

g replaced with f
h replaced with j
o replaced with k
ö replaced with y
/ replaced with p
q replaced with _

Now how do you think i got to know that q is _ ? Uh , simple what does the zeromutarts home page say? it says the format for flag is x_x_x_x  right? :-)

After replacing you will get this :
Dear friend,
I just want to let you know the secret for the encrypted scroll I sent you. Use it wisely and do not give it to anyone.

The secret is> flag_feel_so_bohemian_like_you

Flag : feel_so_bohemian_like_you

Zeromutarts Challenge-1 (404)

Well this is the write up regarding the beginners CTF which was held recently..Got over yesterday but still you can solve the challenges as the site is live..

Website : http://zeromutarts.de

Question :
HTTP codes are kinda fun
Link

The challenge is about Http error codes.So  lets dig in deep what is error 404 from our friend wikipedia.
http://en.wikipedia.org/wiki/HTTP_404

well it tells us that "It is the webpage when user tries to access dead link or broken link".
So just try some random page like login.php..

http://zeromutarts.de:8080/login.php

this would result in :

404 - Not Found

414 is so much better...

so now search what is 414 error,its nothing but a huge link.try randomly giving something and you would land up in flag..

something like this :  http://zeromutarts.de:8080/loginajsdnjsakndakjsdnaskjdnsadniweeuwihnwefjsdnsjdnvjkdsniuwksdnvkjsnvrkjsdvn.php

Now you will see the flag : 
flag{sometimes_error_codes_are_just_a_teapot}