Problem
Table of Content
- 1. Capture the flag!
- 2. cheap cipher
- 3. cheap cipher (revenge)
- 4. directories
- 5. The flag is a lie.
- 6. Game #1
- 7. alphabet?
- 8. Horizontal line
- 9. encode-encode
- 10. easy crackme
- 11. hiragana
- 12. ASCII Art
- 13. Yet Another G00913
- 14. from login form
- 15. ZIP is zip
- 16. medium crackme
- 17. Fragments of gzip
- 18. Which is the flag?
- 19. stairs
- 20. searcher
- 21. loop
- 22. hidden 1
- 23. Picross
- 24. Gyazo
- 25. HEYYEYAAEYAAAEYAEYAA
- 26. retro crackme
- 27. Online banking
- 28. feel the rhythm
- 29. jpeglitch
- 30. tell me a message
- 31. hidden 2
- 32. simple sqli
- 33. from secure login form
- 34. CAPTCHA the Flag
- 35. console
- 36. iRC
- 37. steg noobs
- 38. super secret notes
- 39. giveme_shellcode
- 40. sudden_death
- 41. Pokemon battle
- 42. unreadable message
1. Capture the flag!
Category: misc
Point: 10
Solved: 1682 / 2216
Writeup
Description
Q1RGCg==
Flag
CTF
2. cheap cipher
Category: crypto
Point: 50
Solved: 1357 / 2216
Writeup
Source code
Description
==AVoVGImxWYnBSazByUzMkUzQ1XLNTW
Flag
S3CR3T_K3Y
3. cheap cipher (revenge)
Category: crypto
Point: 80
Solved: 294 / 2216
Writeup
Source code
Description
rKrUl+/clKHb4u/sm6sgnaPfnO/XkO=ewqPU45bRjp4gwa7NntoM467Onu/enqPRlakgj6Egjp0e1gAA
Flag
All your Base64 are belong to us
4. directories
Category: for
Point: 60
Solved: 671 / 2216
Writeup
Description
directories.zip-22a823d589b0c0b6560cfbae6f6f89c1
Flag
snakebites
5. The flag is a lie.
Category: misc+guessing
Point: 200
Solved: 18 / 2216
Writeup
Description
TheFlagIsALie-8f3cce5cc4d27fcd822437c53f7c8e6b
Hint
Someone broke the beginning of the file.
Flag
HELLO 6502
6. Game #1
Category: web
Point: 70
Solved: 463 / 2216
Writeup
Source code
Description
Flag
YIPPEE
7. alphabet?
Category: crypto
Point: 80
Solved: 123 / 2216
Writeup
Source code
Description
This message is a certain game's monologue. The flag is name of the game in capital letters.
ΥΔΗΖΙΝΔJΙ-ΧJΙΟΜJGGΔΙΒ ΑJΜΟ "ΥJΓ" ΓΥΝ ΙJΡ WΖΖΙ ΥΖΗJGΔΝΓΖΥ, ΥΙΥ ΟΔΗΖ ΝΟΥΜΟΖΥ ΑGJΡΔΙΒ ΜΖQΖΜΝΖGΤ. "QΥΠΝ" ΗΥΙΥΒΖΥ ΟJ ΖΝΧΥΚΖ ΑΜJΗ ΟΓΖ ΥΔΝΟJΜΟΖΥ ΝΚΥΧΖ. WΠΟ ΟΓΖ ΜΖΥG QJΤΥΒΖ JΑ "ΥΜFΥΙJΔΥ" ΔΙ ΟΓΖ ΒΥGΥΣΤ ΓΥΝ JΙGΤ ΝΟΥΜΟΖΥ......
Flag
ARKANOID
8. Horizontal line
Category: misc
Point: 70
Solved: 313 / 2216
Writeup
Source code
Description
hline.gif-74d643f5f6a94f4efba37b2d12c6af30
Flag
PIXEL
9. encode-encode
Category: misc
Point: 90
Solved: 193 / 2216
Writeup
Description
Do not encode byte strings twice, you know. In UTF-8, double encoded bytes (bytes encoded twice) makes me sick.
# regular UTF-8 encode 漢 -> \346\274\242 # encode twice in UTF-8 漢 -> \303\246\302\274\302\242
What is this?
c3:a3:c2:81:c2:8d:c3:a3:c2:82:c2:83:c3:a3:c2:81:c2:b7:c3:a3:c2:81:c2:a1:c3:a3:c2:82:c2:83:c3:a3:c2:83:c2:bc:c3:83:c2:a3:c3:82:c2:83:c3:82:c2:bb:c3:83:c2:a3:c3:82:c2:82:c3:82:c2:b6:c3:83:c2:a3:c3:82:c2:83:c3:82:c2:bb:e3:81:b5:e3:82:89:e3:81:a3:e3:81:90
Flag
きゃぷちゃー・ザ・ふらっぐ
10. easy crackme
Category: bin
Point: 70
Solved: 311 / 2216
Writeup
Source code
Description
easy_crackme-47c32e7cc8eae23d1d8ef5948b3dce4a
Flag
旗RM7RF4o2
11. hiragana
Category: trivia
Point: 90
Solved: 99 / 2216
Writeup
Description
あいうえおかきくけこさしすせそたちつてとなにぬねのはひふへほまみむめもらりるれろがぎぐげござじずぜぞばびぶべぼぱぴぷぺぽやゆよわん
りろみるむのしきむなきしぴぎいきむごばうばけしみむぐぼうざがしきむげじうぺがさぎむじまさぷぴしぜりたてうぜのさゆむげきうぞがしすむごもうがぎこしむごひうびのしほむずきうばこまろるきもうばこかこらじもうぞのさべむげぼいちがさずむじぐうぞぴしむもそぐつびけれゆむごばつてのぽがむげぺうぜのさゆむごばうぐのぺおむごぼうぷがさざりれぼうぺけしへむげれうやのかうらるさなとけしもむざばうばぴさぞむぐぐちねけさべむざばうざのさゆむぐぐそとぷいごむごぼうじぴしぐむごぼうじぴしぐむごぼそぜけしこるろじしちぴしすもぺそつもけしぜむげぬうぞけさもむげぼうびけさよむげじうぎけしかむげまいちがらぐりへばこずのしすもぺそつもけしぜむげぬうぞけさもむげぼうびけさぎむなきそめけしせらりよちふけさぐむごもうぷぴしぞむごぬうぐのさずむじれたもがしむらされうぱけさぷむずきうざのぎぱらにぐうびけぺそらしきうぞのらぐるせてとやはとならりよなべけしきむぐじうぱぴしろむじぐうずのさぞむごひうぴこぬぱむぐじうぱけさぷむずきいちがらぐりへばこずのしすもぺそつもけしぜむげぬうぞけさもむげぼうびけしかむげぬうぷのさりむなきてほよぬいむごぼそぺけしむりひじうぴこえなむぐぼうぞこさぱむぐぼいちのじぷむごれうびのかべむぼれえりぴせぷむねひうぞがよつむぐさうずはこぱぷのきにざがぺひむごばえみのかふむぶぺうやけしうむぐようぞけさもむざばうざのさゆむげぬうばけしみむぐぼうざがしせむぐさうぜがしむもよさうががしげむごばえなぴそあむごばすちぴさざむごさうやけしせむぐさうぞけさもむざばうざのさゆむなさぬるけしへむげぼててぴしせらぺぼうざのさぞむじぼうぺがしおむごぼうががしへむげぬうずのさぐもにぺとげがせぬむぴそえのがせやむずううぐのしなむごきうぞけさもむざばうざのさゆむなさうげぴしぐむごまうぴけしきむごれうぐのさざらりよちふけしきむじうそむけしこむざばうざのさゆむなさてほよぬいむごぼてほよぬいるよようげのしむむじぐうぐぴぷたりそまなぐぎにとるおぺうびけびへらけぺうばははぼむごもうげのしけむじもしぴぎいきむごばうばけしみむぐぼうざがさぐむげじうびけぺみむごばなとがかいりりじうぐぎひなむげじうびけぺみむごばなとがぺあむごれうぱけさべむげぼいちがぷたりきばうびこせむもぶばうやけさぱむげきうざのしれむぐぼてごがしねむごてすぐのしへむげぬうぷのさりむなけん
Flag
蜘蛛となめくじと狸
12. ASCII Art
Category: trivia
Point: 60
Solved: 258 / 2216
Writeup
Source code
Description
Who is this?
''=~('('.('?').
'{'.('['^'+').("\["^
')').('`'|')').('`'|'.').
('[' ^'/'
).(( '"')
).+( '`'^
'$') .''.
('`' |'!'
).+( '`'|
'-') .''.
('`' |((
')') )).(
'`'| '!').( '`'|
'.') .''. ( '{'
^(( '[' ))).('`' ^ '#'
).( ( '`') |(( ( '/'
))) ) .('`'|'.'). ( '['
^(( ( ( ','
))) ) ) .+(
'`' | ( '!'
)). ( ( '['
)^+ ( ( '"'
)) ) . '"'
. (( ( ( ((
( (( ( ( ((
( '}') ))))))))) )))).+ ')'
) ;$: =(( '.' ))^ '~' ;$~
= (( (( '@'))))| '(';$^= ((
( ( (( (( ')') )) ) )) ))^+ (( (
( ( '[' )))));($/) = '`'|'.';$,= (
( ( (( ( (
( (( ( ((
( '(' ) ))
) ))) ) )))
)))^'}' ; $\=
"\`"| ( ( ( '!'
)));( ( ( ( $:)
)))=(( ')'))^'}';$~ ='*'
|"\`"; ($^)
=('+')^ '_';$/='&'|"\@";$,= '['&
"\~";$\= ','^'|';$:='.'^('~');$~= '@'|
"\(";$^= (( "\)"))^
'[';$/="\`"| '.';$,='('^'}';$\= ('`')|
'!';$:=')' ^'}';$~="\*"| "\`";
$^='+'^'_' ;($/)=
'&'|('@');$,= '['&"\~";
$\=','^'|';$:='.'^'~';$~='@'|'('
;$^=')'^'[';$/='`'|'.';$,=('(')^
'}';$\='`'|'!';$:=')'^('}');$~=
'*'|'`';$^='+'^'_';$/='&'|'@';
$,='['&'~';$\=','^'|';$:='.'
^'~';$~='@'|'(';$^=(')')^
'[';$/='`'|'.';$,="\("^
'}';$\='`'|('!');$:=
')'^'}';$~=('*')|
'`';$^='+';
Flag
Damian Conway
13. Yet Another G00913
Category: PPC
Point: 100
Solved: 119 / 2216
Writeup
Description
FLAG_Q13_{first 200-digit prime found in consecutive digits of π}
Flag
FLAG_Q13_54882046652138414695194151160943305727036575959195309218611738193261179310511854807446237996274956735188575272489122793818301194912983367336244065664308602139494639522473719070217986094370277053921717
14. from login form
Category: web
Point: 120
Solved: 114 / 2216
Writeup
Source code
Description
Update: I fixed q14, and it was broken since Apr 26. Sorry ;(
Flag
FLAG_hogee_fuga_piyopiyopiyo
15. ZIP is zip
Category: misc
Point: 110
Solved: 44 / 2216
Writeup
Source code
Description
You can capture the flag by sorting.
zip.zip-ded3b0a45d60b9d834025daab478e1a1Flag
BDVNCpguUQSjsZJ
16. medium crackme
Category: bin
Point: 130
Solved: 70 / 2216
Writeup
Source code
Description
The flag is **********.
Flag
gD0Fbs3642
17. Fragments of gzip
Category: misc
Point: 80
Solved: 133 / 2216
Writeup
Description
I'm missing gzip header. But there is only compressed data:
d3:2d:03:03:85:dc:fc:7c:2e:00:22:4a:78:e2:0c:00:00:00:0a
Flag
-vvvvvv moo
18. Which is the flag?
Category: web
Point: 90
Solved: 130 / 2216
Writeup
Source code
Description
Flag
RegularExpression
19. stairs
Category: crypto
Point: 80
Solved: 69 / 2216
Writeup
Source code
Description
G NrD NdeyM muNaHnh ZDpJtRSLp vypFhPXzxLB wVBISmyIhtMTQ XeLOfAFrVjAESSf lIzxxAnyangFlzLAQ VESahvDXtmnKNBRpIkf pSMRLNFnHViPJhqvuhrrp fymLjhBJlZFdNlYswhNlImR lKzWwzjlpigqOHVSnNxxgpScc wyoHPACOBPTGZfmXDBAHdWDHrcV pXIZwFMTQuWdSgGHgtUtiBXcGEDGh gMaGyanBffyKcGFiQjRnqSrvOrlJYFb vHCWLsqPRiUcCwMuzioVrOmEjQwffudND wnkDeijzqzRHzNVwZaWsZvMrhlsLjRGUFbe
Flag
GreatPyramidOfGiza
20. searcher
Category: web
Point: 180
Solved: 36 / 2216
Writeup
Source code
Description
Hint
CREATE TABLE IF NOT EXISTS user (
user_id INTEGER NOT NULL PRIMARY KEY,
name VARCHAR(255) NOT NULL,
password VARCHAR(255) NOT NULL,
UNIQUE (name)
);
Flag
ADMINIMDA
21. loop
Category: web
Point: 70
Solved: 182 / 2216
Writeup
Source code
Description
Do not attack :)
Flag
6890c6f34d3c3ad95cfa13ab321943d7
22. hidden 1
Category: web
Point: 100
Solved: 63 / 2216
Writeup
Description
:)
Flag
xcomglobal
23. Picross
Category: PPC
Point: 250
Solved: 11 / 2216
Writeup
Source code
Description
nc ctf.katsudon.org 17023
Flag
280fa17f505ccf7ee308cb5d021c5565
24. Gyazo
Category: web+guessing
Point: 210
Solved: 20 / 2216
Writeup
Source code
Description
Hint
- flag.png
- accesscode = md5(salted_filename)
Flag
Ninjas can't catch you if you're on fire.
25. HEYYEYAAEYAAAEYAEYAA
Category: steg
Point: 80
Solved: 87 / 2216
Writeup
Description
The sound can not be heard.
HEYYEYAAEYAAAEYAEYAA.wav-a7cb9e1dc56ef5597a9535ae353dcb13Flag
HEYSPECTROGRAM
26. retro crackme
Category: bin
Point: 150
Solved: 13 / 2216
Writeup
Source code
Description
retro_crackme-96b844b59fbd6270ef03b510a3f21e3b
Flag
looking for l0ve s0ng
27. Online banking
Category: web
Point: 270
Solved: 18 / 2216
Writeup
Source code
Description
What is the initial amount of john?
Hint
- did you try to login as john?
- http://q27.ctf.katsudon.org/404
Flag
294307500
28. feel the rhythm
Category: misc
Point: 90
Solved: 46 / 2216
Writeup
Source code
Description
rhythm.wav-d08530ac6de2a8601cef1a7b2a0dc6fa
Flag
CAMEL2
29. jpeglitch
Category: misc
Point: 120
Solved: 71 / 2216
Writeup
Source code
Description
The glitch algorithm is simple, like this:
perl -i -pe's/a/b/g' flag.jpgglitch.zip-06718696c3e01de29d4d8f577004f537
Flag
glitch_5157cc4572
30. tell me a message
Category: bin+guessing
Point: 230
Solved: 4 / 2216
Writeup
Description
This program cannot print a character well... but it's simple :)
tellme-39079dcc9a39dfb72bc6f40842bdeac8
Update: This problem has a bug. You can solve it, but maybe unreasonable... I'm going to provide new binary, just a moment :)
Hint
you can get a message by brute-force attack. have you tried the input of all possible?
Flag
ﾐﾝﾅﾆﾊﾅｲｼｮﾀﾞﾖ
31. hidden 2
Category: guessing
Point: 120
Solved: 13 / 2216
Writeup
Description
find the "flag" :)
Hint
not A
Flag
dead::beef
32. simple sqli
Category: web
Point: 160
Solved: 19 / 2216
Writeup
Source code
Description
Hint
- I thought this validates 'id' as a number...
- and I'm using regexp.
Flag
700_51mpl3_27307d6c315d96bb5ea96b5830ca1e6a
33. from secure login form
Category: web
Point: 180
Solved: 17 / 2216
Writeup
Source code
Description
Flag
r1v357
34. CAPTCHA the Flag
Category: PPC
Point: 150
Solved: 31 / 2216
Writeup
Source code
Description
Flag
CcaaAPpTTTCccHhA
35. console
Category: web
Point: 240
Solved: 29 / 2216
Writeup
Source code
Description
available commands: login, register, ...
Flag
p4zzw0rd_m0n573r_willin9ly_347z_saltimbocca
36. iRC
Category: web
Point: 150
Solved: 6 / 2216
Writeup
Source code
Description
<akiym> I'm thinking about Q36... <evilhacker> how about irc bot? <akiym> evilhacker: good idea. why don't you make a irc bot with me? <evilhacker> sounds good <akiym> :) <akiym> have you ever made a irc bot? <evilhacker> no <akiym> okay. I'll give you source code <akiym> but you don't discover the flag, right? <evilhacker> of course ;) <akiym> I sent <evilhacker> akiym++ akiym has left #akictf-meeting <evilhacker> his source code is perfect <evilhacker> so I made a vulnerability, hahaha
akictf-q36 is in irc.freenode.net.
Note: You DO NOT access/attack ctf.katsudon.org:6669. This is unrelated. (my personal IRC bouncer :-)
Update: akictf-q36 is unstable. It replies to such message: akiym++ If it doesn't reply, please send an email or just a moment.
Flag
I <3 SQLite!
37. steg noobs
Category: steg
Point: 180
Solved: 18 / 2216
Writeup
Description
steg_noobs.zip-5d05a159662f59e65b1f9c3113832f7c
Flag
d0_y0u_like_stegan0__i_hate~~
38. super secret notes
Category: web
Point: 300
Solved: 6 / 2216
Writeup
Source code
Description
find the flag.
Hint
1) 1st flag in source
2) 
Flag
7rAv3r5AL_w17H_8yPA55_f0R_1nJ3c710n
39. giveme_shellcode
Category: pwn
Point: 200
Solved: 35 / 2216
Writeup
Source code
Description
nc pwnable.katsudon.org 17039giveme_shellcode-eebca4141478c0dc649459a2d897bc2a
Flag
5H3LLC0D3_G0Lf_15_345Y
40. sudden_death
Category: web+pwn
Point: 320
Solved: 13 / 2216
Writeup
Source code
Description
http://pwnable.katsudon.org:17040/
Flag
5UDD3n_539M3N74710N_f4ul7~
41. Pokemon battle
Category: web
Point: 250
Solved: 12 / 2216
Writeup
Source code
Description
pokemon!
http://q41.ctf.katsudon.org/
DO NOT BRUTE FORCE!
Update: Sorry, I fixed a mistake. see source again :P
Update: So sorry, Marumain and Mewtwo was too weak. see source again again ;(
Flag
w4NN483_p0k3MON_M4573R
42. unreadable message
Category: misc
Point: 180
Solved: 9 / 2216
Writeup
Description
Here is unreadable message. Could you try to restore my message?
download unreadable_message.zip-a2bed73cbd988469a22cde41320bbcf4
Flag
brute_it_if_you_could_not_read