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FireShell CTF 2020 Writeups

FireShell CTF had been held from March 22th JST for 24 hours. I played this CTF in zer0pts and we reached 3rd place. I solved only two pwn tasks and one easy crypto/rev, but the pwn tasks are tough and I'm going to write the solutions for …

SuSeC CTF 2020 Pwn Writeups

SuSeC CTF 2020 had been held from 15th March 06:30 UTC for 36 hours. I wrote 3 pwn tasks for this CTF. (I don't know of any other tasks.) The tasks and solvers are available here: bitbucket.org I hope you enjoyed my pwn challenges :) [182p…

CONFidence CTF 2020 Teaser Writeups

I played CONFidence CTF 2020 in zer0pts. We got 786pts in total and reached 19th place. It was pretty hard but a fun CTF. Other members' writeups: st98.github.io Files and solvers for some challenges: bitbucket.org [misc 37pts] Hidden Flag…

Codegate CTF 2020 Preliminary Writeup

I played Codegate CTF 2020 in shibad0gs. I was busy for another upcoming event and couldn't work on it full time but I solved some challenges and we reached 30th place. As the challenge doesn't have category, I randomly picked up tasks. [3…

HackTM CTF Quals 2020 Writeup

HackTM CTF was held from February 1st to 3rd for 48 hours. I played it in zer0pts and we reached to 8th place. Thank you @WreckTheLine for hosting the CTF! The tasks and solvers for some challenges I solved are available here: bitbucket.or…

NITAC miniCTF 3rd 作問writeup

こんなCTFがあったんで参加しようと思ったのですが、こんなツイートを見て作問お手伝いすることにしました。 作問に参加した時点では割と自明問が多く、某氏とか某氏に即全完されそうな感じだったので、私は若干難しめのものを作りました。 といっても初心者…

Insomni'hack teaser 2020 Writeup

I played Insomni'hack teaser 2020 in shibad0gs. There're only 1 misc, 1 rev, 1 forensics, 3 crypto and 4 web. We solved 4 tasks in the first 4 hours and that's it lol. As the web tasks are too guessy, I just solved the misc, forensics and …

Gomium BrowserのWriteup【Google CTF 2019 Finals】

はじめに 今日サイバーセキュリティ系LT会というのに参加したのですが、そこでhamaさんが発表されていたgoの処理系がunsafeな話が面白かったので、解説されていた問題を解こうと思います。 内容はgoには標準でdata raceが存在し、任意のgoコードが実行出来る…

Contrail CTF 2019のWriteup

Contrail CTFが12月30日から1月4日まで開催され、zer0ptsで参加しました。 全体で4786点を獲得して1位でした。 解いた問題のwriteupを簡単に書きます。 [pwn 100pts] welcomechain [pwn 304pts] instant_httpserver [pwn 356pts] babyheap [pwn 100pts] poke…

BambooFox CTF 2019-2020 Writeup

BambooFox CTF had been held from December 31th to January 1st. I played it a bit in zer0pts and we stood 5th place. All of the pwn-related tasks were very fun! Thank you for hosting the CTF and happy new year :) [Pwn 323pts] note [Pwn 357p…

Christmas CTF 2019 Writeup

XMAS CTF was held in Christmas for those who are lone! We zer0pts played this CTF and I worked on pwn tasks which are well-designed. I couldn't work on it full-time because I had school but still enjoyed the CTF :) [rev 919pts] welcome rev…

2019年のpwn問を全部解くチャレンジ【後半戦】

この記事はCTF Advent Calendar 2019の23日目の記事です。 はじめに この記事は「2019年のpwn問を全部解くチャレンジ【前半戦】」の続きで、解く対象の問題も前の記事と基本同じです。 が、ちょっと条件を追加します。 javascriptや独自vm、コンパイラ、イン…

SECCON CTF 2019 FinalのWriteup

2019年もSECCONが秋葉原で開催されました。 今回はNaruseJunで国際決勝に参加し、最終的には4323点を獲得して1位でした。 SECCONについて 国内チームも参加しやすい敷居の低い競技を毎年開催していただき感謝です。 ただ年々セキュリティコンテストからプロ…

watevrCTF 2019 Writeup

I played watevrCTF, a Swedish CTF held from December 13th to 15th, in zer0pts. We got 4869pts and stood 3rd place. Most of tasks are well-designed and I really enjoyed the CTF. Thank you to watevr for hosting the CTF! [pwn 33pts] Voting Ma…

CTFZone 2019 Quals Writeup

I played CTFZone 2019 Quals in zer0pts. Our team got 879pts and kept 37th place. Thank you for organizing the CTF. Here's the tasks and solvers for some challenges I solved. https://bitbucket.org/ptr-yudai/writeups/src/master/2019/CTFZone_…

TSG LIVE! CTF 4のwriteup

なんかtwitterで流れてたのでzer0ptsで参加しました。 75分という短時間で早解きが要求されるCTFです。 TSGの問題は良問が多いので好きです。75分なので問題数は少なかったですが、チームメンバーの様子を見ていても面白い問題が多かったようです。 私はpwn…

Newbie CTF 2019 Writeup

I played Newbie CTF which was held from November 2nd to 3rd in zer0pts. The CTF had some problems in their challenges, servers, and so on but I enjoyed it. We got 15849pts and reached 1st place. Here I'm going to write the solutions for pw…

hack.lu CTF 2019 Writeup

I played hack.lu CTF 2019 in zer0pts. Although I couldn't play it full-time as it was in weekdays, I managed to solve some challenges after school. We got 1709 points and reached 27th place. It was a fun CTF and I enjoyed it. Thank you for…

SECCON Online 2019 QualsのWriteup

SECCON Online 2019 Qualificationが10月19日の15:00(JST)から24時間開催されました。 今年はNaruseJunで参加し、全体で5位でした。 1時間程度しか寝ていないので疲れましたが、オンサイトでわいわい解くのは楽しかったです。通したフラグは合計で1736点でし…

SquareCTF 2019 Writeup

SquareCTF had been held from October 11th to 17th (in JST) and I played it in zer0pts. We got 6450 points and kept 7th place. There are many good challenges and I enjoyed them! Thank you for hosting the CTF :) [Reversing 700pts] Aesni [Cry…

Layer7 CTF writeup

Layer7 CTF had been held from October 6th to 7th. It's a sole-play CTF and I played it as ptr-yudai. There were so many challenges that I couldn't even check all of them, especially web challenges. I got 1711pts and kept 4th place. [Pwn 10…

SEC-T CTF 2019 Writeup

SEC-T CTF 2019 had been held from September 18th, 15:00 to 19th, 21:00 UTC. I played this CTF in zer0pts and we reached 6th place with 4485pts. It was a really nice CTF and I learned a lot. Thank you for hosting the CTF! [misc 79pts] sanit…

TokyoWesterns CTF 5th 2019 Writeup

TokyoWesterns CTF 5th 2019が日本時間で8/31 09:00から9/02 09:00まで開催されました。 私はチームHarekazeとして参加し、Harekazeは1481点を獲得して33位でした。 そのうち5問を私は解いたので、そのwriteupを書こうと思います。 [Pwn 78pts] nothing more…

RedpwnCTF 2019 Writeup

RedpwnCTF 2019 had been held from Aug 12th to 16th and I played this CTF in zer0pts. We got 4433pts and reached 29th place. I gained 3605pts, solving mostly pwn and some forensics, misc, crypto, rev challs. In this post I'll write only abo…

CyBRICS CTF 2019 Writeup

I played CyBRICS CTF 2019 in zer0pts. Our team got 386pts and reached 69th place. It's not a good result but I really enjoyed the CTF as there were many well-designed challenges. [Forensics 67pts] Disk Data [Cyber 50pts] QShell [Network 10…

ISITDTU CTF 2019 Quals Writeup

ISITDTU CTF 2019 took place from June 29th for 25 hours. I played this CTF in zer0pts and we reached the 10th place. Thank you for holding the CTF. I enjoyed it :-) [Pwn 395] iz_heap_lv1 [Pwn 908] Tokenizer [Pwn 738] babyshellcode [Cryptog…

HSCTF 6 Writeup

I played HSCTF 6 in yoshikingdom and our team reached 11th place. I didn't plan to play this CTF but @y05h1k1ng suggested us to play this one as a joke (not in ordinary team) because it was about to the end of the CTF. So, 11th place in ha…

Facebook CTF 2019 Writeup

Facebook CTF 2019 had been held from June 1st 00:00 UTC to June 2nd 00:00 UTC. I played this CTF as a member of zer0pts. We got 9372pts and reached 18th place. I solved several challs and gained 4718pts. The CTF was pretty hard but I reall…

SECCON Beginners CTF 2019のWriteup

5月25日(土)15:00から24時間開催されたSECCON Beginners CTF 2019にzer0ptsのメンバーで参加しました。 大会の存在をすっかり忘れていたので途中から参加しましたが、担当分野は無事全部解くことができました。 初心者向けながら典型とは外れたものもあり、…

Harekaze CTF 2019のWriteup

5月18日の15時から24時間Harekaze CTF 2019が開催されました。 私はチームYokosuka Hackersとして参加し、チーム全体で3060ptsを獲得して1位でした。 なんとフラグを通したのは2問だけという失態ですが、今回はみんなで情報共有して協力しながらという感じだ…