[{"_1":2,"_3":-5,"_4":-5},"loaderData",{"_5":6,"_7":8,"_9":10,"_11":12,"_13":14},"actionData","errors","root",{"_151":152,"_153":146},"routes/_root/_root",{"_148":-7,"_39":149,"_120":-7,"_150":-7},"routes/_root.challenges",{"_35":144,"_145":146,"_147":16},"routes/_root.challenges.$challengeCanonical+/_root",{"_54":55,"_56":57,"_58":59},"routes/_root.challenges.$challengeCanonical+/writeups",{"_15":16,"_17":16,"_18":19,"_20":21,"_22":23},"solved",false,"hasWriteup","writeups",[24,25],"name","AlpacaForm","canonicalName","alpaca-form",{"_26":47,"_28":48,"_30":49,"_32":16,"_33":16,"_34":16,"_35":50,"_37":51,"_39":40,"_41":16,"_42":52},{"_26":27,"_28":29,"_30":31,"_32":16,"_33":16,"_34":16,"_35":36,"_37":38,"_39":40,"_41":16,"_42":43},"author",{"_20":44,"_45":46},"writeupElementId","1a62fcca","writeupId","1a62fcca-0bd2-44cc-a102-f76e42750796","canEdit","canLike","likedByViewer","title","Writeup for AlpacaForm","url","https://github.com/tadanobutubutu/alpaca-form-solve/blob/main/README.md","language","ja","isOfficial","createdAt",["D",1779981065798],"tadanobutubutu","gravatarHash","32d088d6e11be98c7280952c1fdfeb6a6ee1b5056555fe814e35720483c99e51",{"_20":53,"_45":-5},"a3097eb5","a3097eb5-9ee9-4812-bc0f-23bc508912ab","Daily AlpacaHackに挑戦するつくよみちゃん 05/28/AlpacaForm/shiragi","https://www.nicovideo.jp/watch/sm46367418",["D",1779983247125],"tsukuyomi-chan","challenge",{"_20":21,"_22":23,"_63":64,"_65":66,"_67":68,"_69":70,"_71":-7,"_72":73,"_74":75,"_76":16,"_77":-7,"_78":79,"_80":-7,"_81":-7,"_34":16,"_82":83,"_84":85,"_86":16,"_87":-7,"_88":16,"_89":-7,"_90":-7,"_91":92,"_93":-7,"_94":-7,"_95":-7,"_96":97,"_98":16,"_99":97,"_33":97,"_100":-7,"_101":102,"_103":104,"_105":106,"_107":108},"availablePages",[60,61,62],"canonicalUrl","https://alpacahack.com/challenges/alpaca-form","Description","Solves","Writeups","solves",73,"flagFormat","Alpaca{...}","categories",[141],"attachments",[137],"remote","description","\"This challenge can be solved on Linux alone.\"\n\n

Beginner Hint 1: Challenge Overview (AI-translated)

\n\n- The distributed files are a .NET application written in C# and a [flag checker](https://alpacahack.com/tags/flag-checker) that determines whether the entered string is the correct flag.\n- `AlpacaForm.exe` is the executable file used to launch the app on Windows. The C# code containing the actual validation logic is in `AlpacaForm.dll`.\n- `.dll` stands for Dynamic Link Library. In general, it is a file that contains code or data loaded and used by executable files or other programs.\n

\n\n

Beginner Hint 2: Reverse Engineering (AI-translated)

\n\n- `AlpacaForm.dll` can be decompiled and read in a form close to C# using a .NET decompiler such as ILSpy.\n- For example, try running `ilspycmd AlpacaForm.dll` to decompile it ([Ref](https://github.com/icsharpcode/ILSpy/tree/98ee6c3b8410e495b2fbbe9ca414090a962202c8/ICSharpCode.ILSpyCmd)).\n- After decompiling it, look for the function that validates the entered string.\n

\n","descriptionJa","\"この問題はLinux環境だけでも解けます。\"\n\n

初心者向けヒント1: 問題概要

\n\n- 配布ファイルは、C# で作られた .NET アプリケーションで、入力された文字列が正しいフラグかどうかを判定する[フラグチェッカー](https://alpacahack.com/tags/flag-checker)です。\n- `AlpacaForm.exe` は Windows でアプリを起動するための実行ファイルです。実際の判定処理を含む C# のコードは、`AlpacaForm.dll` に含まれています。\n- `.dll` は Dynamic Link Library の略で、一般には実行ファイルなどから読み込まれて使われるコードやデータを含むファイルです。\n

\n\n

初心者向けヒント2: リバースエンジニアリングの方法

\n\n- `AlpacaForm.dll` は ILSpy などの .NET デコンパイラで、C# に近い形へデコンパイルして読めます。\n- 例えば `ilspycmd AlpacaForm.dll` を実行してデコンパイルしてみましょう（[参考](https://github.com/icsharpcode/ILSpy/tree/98ee6c3b8410e495b2fbbe9ca414090a962202c8/ICSharpCode.ILSpyCmd)）。\n- デコンパイルしたら、入力された文字列を検証している関数を探してみましょう。\n

\n","descriptionRequiresSignIn","changeLog","authors",[134],"solvedAt","solvedAtInContext","ctfChallenges",[],"tags",[122,123,124,125],"submitAsCtfChallenge","ctfCanonical","ctfEnded","point","solvesCtfChallenge","classification","medium","isMirror","ctfParticipants","ctfMode","isDailyChallenge",true,"canCheckFlagWithoutSubmission","canCreateInstance","dailyProgramCanonicalForAction","previewProgramCanonicalForAction","daily-alpacahack","dailyChallengeSlot",{"_109":110,"_91":92,"_111":112,"_113":114,"_115":116,"_117":118},"nextDailyCanonical","decrypt-shop","httpsProxyHostname","alpaca-form.chal.alp4ca.com","program",{"_22":102,"_20":119,"_120":121},"scheduledDate",["D",1779894000000],"releaseAt",["D",1779894000000],"status","PUBLISHED","plannedTopic",".NET","Daily AlpacaHack","timeZone","Asia/Tokyo",{"_20":132,"_22":133},{"_20":130,"_22":131},{"_20":128,"_22":129},{"_20":126,"_22":127},"Csharp","csharp","Dotnet","dotnet","Windows","windows","Flag Checker","flag-checker",{"_20":135,"_45":136},"shiragi","c22e446c8c70b52ed5707e9939f191b7d2ee4d10fba60300b54ea68099cea638",{"_138":139,"_37":140},"fileName","alpaca-form.tar.gz","https://alpacahack-prod.s3.ap-northeast-1.amazonaws.com/bab9feb9-a5eb-4c06-9e30-e35227ac9673/alpaca-form.tar.gz",{"_20":142,"_22":143},"Rev","rev","Challenges","query","","isLoggedIn","user","en","timeZoneAbbr","clientConfig",{"_154":155,"_156":97,"_157":158,"_159":158,"_160":161,"_162":163,"_164":16,"_165":146},"cspNonce","firebaseOptions",{"_166":167,"_168":169,"_170":171,"_172":173,"_174":175,"_176":161},"isVercel","env","production","envName","gaTrackingId","G-FJX5L5Y9FE","turnstileSiteKey","0x4AAAAAAAfYTP7SUci3nVKW","isSpawnerUnderMaintenance","spawnerMaintenanceNotice","apiKey","AIzaSyDGInmUCFubPOqJWQCw3LBB-XZGj9LX4l4","appId","1:691353492123:web:4ae258ec8c620e63f0443e","projectId","alpacahack","authDomain","alpacahack.firebaseapp.com","messagingSenderId","691353492123","measurementId"]