TryHackMe(THM):c4ptur3-th3-fl4g

目次

Task 1 Translation & Shifting

暗号　：　c4n y0u c4p7u23 7h3 f149?

Universal Leetにアクセスして問題の文字列を「Input」エリアに貼り付けて[decode]ボタンを押下します。

いくつか変換に失敗しているが文章がわかるぐらいまで解析されます。

4 -> a、 0 -> o、 7 -> t、1 -> l、 9 -> g、2 -> r、3 -> eに変換してみると、答えが出てくる。

暗号　：　01101100 01100101 01110100 01110011 00100000 01110100 01110010 01111001 00100000 01110011 01101111 01101101 01100101 00100000 01100010 01101001 01101110 01100001 01110010 01111001 00100000 01101111 01110101 01110100 00100001

cyber chefを使って問題の2進数をinput領域に貼り付ける。

検索ボックスに「binary」と入力して「From binary」をrecipe欄にドラックすると答えが出てくる。

暗号　：　MJQXGZJTGIQGS4ZAON2XAZLSEBRW63LNN5XCA2LOEBBVIRRHOM======

問題文が英大文字と数字の組み合わせ、かつ文字列の後ろに=でパディングされているので「BASE32」とあたりをつける。

cyber chefを使って問題文をinput領域に貼り付ける。

検索ボックスに「BASE32」と入力して「From BASE32」をrecipe欄にドラックすると答えが出てくる。

BASE32とは

• バイナリ文字列とテキスト文字列の変換（エンコード or デコード）を行うアルゴリズム。
• エンコードされたテキスト文字列は、A-Z(26文字) と 2-7(6文字)、= の 33文字で構成される。
• 大文字小文字の区別がない環境でも利用可能。
• エンコードは、40ビット(5文字)単位を、8文字に変換していく。
• 40ビットに満たない場合は、= パティングする。

暗号　：　RWFjaCBCYXNlNjQgZGlnaXQgcmVwcmVzZW50cyBleGFjdGx5IDYgYml0cyBvZiBkYXRhLg==

今度は英小文字も含まれているので「Base64」とあたりをつける。

cyber chefを使って問題文をinput領域に貼り付ける。

検索ボックスに「BASE64」と入力して「From BASE64」をrecipe欄にドラックすると答えが出てくる。

暗号　：　68 65 78 61 64 65 63 69 6d 61 6c 20 6f 72 20 62 61 73 65 31 36 3f

cyber chefを使って問題文をinput領域に貼り付ける。

検索ボックスに「Hex」と入力して「From Hex」をrecipe欄にドラックすると答えが出てくる。

暗号　：　Ebgngr zr 13 cynprf!

cyber chefを使って問題文をinput領域に貼り付ける。

検索ボックスに「ROT13」と入力して「ROT13」をrecipe欄にドラックすると答えが出てくる。

暗号　：　*@F DA:? >6 C:89E C@F?5 323J C:89E C@F?5 Wcf E:>6DX

今度は記号が含まれているので「ROT47」にあたりをつける。

cyber chefを使って問題文をinput領域に貼り付ける。

検索ボックスに「ROT47」と入力して「ROT47」をrecipe欄にドラックすると答えが出てくる。

暗号　：　- . .-.. . -.-. --- -- -- ..- -. .. -.-. .- - .. --- -.
. -. -.-. --- -.. .. -. --.

モールス信号らしい。

cyber chefを使って問題文をinput領域に貼り付ける。

検索ボックスに「MORSE」と入力して「From Morse Code」をrecipe欄にドラックすると答えが出てくる。

暗号　：　85 110 112 97 99 107 32 116 104 105 115 32 66 67 68

HEXの問題に比べて、この暗号文には文字列がないことがわかる。

cyber chefを使って問題文をinput領域に貼り付ける。

検索ボックスに「decimal」と入力して「From Decimal」をrecipe欄にドラックすると答えが出てくる。

暗号　：　LS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLi0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLS0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLi0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLi0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLS0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLS0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLS0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLi0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLi0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLS0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLi0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLS0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLi0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLi0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLi0tLS0gLi0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLS0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0gLi0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLi0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0KLS0tLS0gLi0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLi0tLS0KLS0tLS0gLS0tLS0gLi0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0gLS0tLS0KLS0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暗号文がブラウザからはみ出ている。最後に=でパティングされているので「BASE64」であたりをつける。

cyber chefを使って問題文をinput領域に貼り付ける。

• 検索ボックスに「BASE64」と入力して「From BASE64」をrecipe欄にドラックすると、output欄に「モールス信号」の情報が表示された。
• 次に検索ボックスに「morse」と入力して「From Morse Code」をrecipe欄にドラックすると、output欄に「バイナリ」の情報が表示された。
• 次に検索ボックスに「binary」と入力して「From binary」をrecipe欄にドラックすると、output欄に記号を含む英字が表示された。
「ROT47」とあたりつける。
• 次に検索ボックスに「ROT47」と入力して「ROT47」をrecipe欄にドラックすると、output欄に3桁までの英字なしの数字が表示された。
「decimal」とあたりをつける。
• 次に検索ボックスに「decimal」と入力して「From decimal」をrecipe欄にドラックすると、答えが出てくる。

最後の問題は、Task1の問題のいくつかを複合したものでした。

CyberChefを使えばほとんどの問題を解くことができます。

Task 2 Spectrograms

スペクトログラムとは、信号の周波数スペクトルが時間とともに変化する様子を視覚的に表したものです。音声信号に適用される場合、スペクトログラムはソノグラフ、ボイスプリント、ボイスグラムと呼ばれることもある。また、データを3Dプロットで表現したものは、ウォーターフォールと呼ばれることもある。

[Download Task Files]ファイルボタンを押下すると、wavファイルがダウンロードできる。

先人の知恵を拝借すると、

WavePad - 無料ダウンロード

をダウンロードして解析するらしい。

ダウンロードしたwavファイルを開き、[ツール]－[TFFT]を選択すると、答えが表示される。

Task 3 Steganography

ステガノグラフィとは、ファイル、メッセージ、画像、またはビデオを、別のファイル、メッセージ、画像、またはビデオの中に隠すことです。

[Download Task Files]ファイルボタンを押下すると、jpgファイルがダウンロードできる。

stegosteg.jpg

これも先人の知恵を拝借すると、

futureboy.us

を使用するらしい。

[ファイルを選択]でダウンロードしたjpgファイルを選択、[送信]ボタンを押下すると、答えが出ます。

Task 4 Security through obscurity

[Download Task Files]ファイルボタンを押下すると、jpgファイルがダウンロードできる。

これも解き方がわからなかったので先人の知恵を拝借すると、ダウンロードしたファイルをテキストエディタで開くらしい。

最後の数行まで行くとそれらしいテキストが表示されていた。

これらの文字列を入力すると解答だったらしい。

完了！