SECCON Beginners CTF 2021 Web問Writeup ～全集中ExtensionでCTFでも全集中～ 

# 概要
[SECCON Beginners CTF 2021](https://www.seccon.jp/2021/seccon_beginners/_seccon_beginners_ctf_2021.html) のWeb問Writeup（全6問<del>中5問</del>）です。
全集中Burp Extensionこと [ISTE: Integrated Security Testing Environment](https://github.com/okuken/integrated-security-testing-environment/blob/master/README.ja.md)[^1] を携えて参戦し、全集中効果(?)により3時間で5問クリア！（6問目はお察し）

追記：6問目の事後Writeupを追加しました。

[^1]: [ISTE: Integrated Security Testing Environment](https://github.com/okuken/integrated-security-testing-environment/blob/master/README.ja.md) ：Webアプリケーションの脆弱性診断をトータルサポートする Burp extension（Burp Suiteの拡張機能）です。診断員を煩雑な作業から解放し、全集中へと導きます。なお、Writeup中の画面キャプチャはISTEの画面です。良かったらGitHubスター付けつつ使ってみてください。

# osoba（想定難易度: Beginner）
* Directory Traversal
![1-1.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/b7d1e553-e9b1-bc57-0070-cd83f3d659d3.png)
![1-2.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/b0db8171-4e3f-5ab3-50ed-00fabf08db71.png)
![1-3.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/aec6c22f-75f4-2e52-5cbf-22e4727f8e20.png)

# Werewolf（想定難易度: Easy）
* Mass Assignment
![2-1.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/e079fefd-ab20-cd00-1de0-a21e6c8949da.png)
![2-2.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/067617e3-55d1-81a7-63bf-297fcb1dae10.png)
![2-3.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/45c4be7d-88f0-d9c1-23bf-93c9a8f69884.png)

# check_url（想定難易度: Easy）
* SSRF(Server Side Request Forgery)
![3-1.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/710571ab-a362-ec76-d859-388b48c6ad13.png)
![3-2.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/2a07fa5c-f42c-e963-d9c0-6cf65eff067d.png)
![3-3.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/bcdc80c8-d3b4-b5ad-f990-707f625997ed.png)

# json（想定難易度: Medium）
![4-1.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/4ee33c8c-7e28-3c1a-ff21-74e1cc3ba4ff.png)
![4-2.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/ed501adc-b782-5e4a-83de-0203786c0e86.png)
![4-3.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/944dc18d-b451-beef-394c-98d52ecb0e62.png)

# cant_use_db（想定難易度: Medium）
* Race Condition
![5-1.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/4caecf4a-c451-4b5f-f3a6-e44d48af50ab.png)
![5-2.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/cd704362-288c-4bc8-6f89-997fce2320f9.png)
![5-3.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/39b9f640-0413-0912-c6d1-712b3be0f448.png)

# magic（想定難易度: Hard）
※競技終了後に実施した内容です。[作問者様のWriteup](https://hi120ki.github.io/blog/posts/20210523-3/) を参考にしつつ、adminにFlagをMemo登録させる方法でやってみました。

* XSS(Cross-Site Scripting)
![6-1.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/6715709c-3bda-e361-ec30-11d058b43c8d.png)
![6-2.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/27c3e91c-8e6c-91a0-0e71-cabd54deef8e.png)
![6-3.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/e1d9ba17-16d0-7588-0065-f3d7e9f2fc6d.png)
![6-4.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/4f32ac8c-198b-482b-ef7b-b35ecd4d485f.png)
![6-5.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/970283e8-951b-9118-d49a-2b126ba6ff49.png)
![6-6.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/63b1ce3d-e6a6-b31f-3ea1-fb205e5757ae.png)
![6-7.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/5a8d23a7-d484-9fe3-5ac5-15927977028d.png)
![6-8.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/1541396/a6f3a2b3-c21b-3d84-ebdc-0205ff23dc72.png)