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HTB Cyber Apocalypse CTF 2024

Posted Mar 20, 2024
By zzre
39 min read

Introduction

저번 주에 Friendly Maltese Citizens 연합팀으로 HTB Cyber Apocalypse CTF에 참여해서 1등했다!

봤던 문제들을 정리해봤다.

Metagaming - 325pts

main.cpp가 주어진다.

CTF 시작할 때 로그인이 안 돼서 늦게 봤는데 운 좋게 first blood했다.

main.cpp 

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// Use MSVC or `g++ -std=c++20`

#include <cstdint>
#include <array>
#include <iostream>
#include <numeric>
#include <type_traits>
#include <algorithm>
#include <variant>

#ifndef __noop
#define __noop
#endif

constexpr uint32_t rotr(const uint32_t value, const int shift) {
    return std::rotr(value, shift);
}

constexpr uint32_t rotl(const uint32_t value, const int shift) {
    return std::rotl(value, shift);
}

template<class, class>
constexpr bool is_same_v = false;

template<class Ty>
constexpr bool is_same_v<Ty, Ty> = true;

struct true_t {};
struct false_t {};

template<class Ty>
concept bool_t = is_same_v<Ty, true_t> || is_same_v<Ty, false_t>;

template<bool Val>
struct to_bool {
    using T = false_t;
};
template<>
struct to_bool<true> {
    using T = true_t;
};
template<bool Val>
using to_bool_t = typename to_bool<Val>::T;
template<bool_t Ty>
constexpr bool from_bool_v = is_same_v<Ty, true_t>;

template<char C>
struct char_value_t {
    [[nodiscard]] constexpr static char value() {
        return C;
    }
};

struct a : char_value_t<'a'> {};
struct b : char_value_t<'b'> {};
struct c : char_value_t<'c'> {};
struct d : char_value_t<'d'> {};
struct e : char_value_t<'e'> {};
struct f : char_value_t<'f'> {};
struct g : char_value_t<'g'> {};
struct h : char_value_t<'h'> {};
struct i : char_value_t<'i'> {};
struct j : char_value_t<'j'> {};
struct k : char_value_t<'k'> {};
struct l : char_value_t<'l'> {};
struct m : char_value_t<'m'> {};
struct n : char_value_t<'n'> {};
struct o : char_value_t<'o'> {};
struct p : char_value_t<'p'> {};
struct q : char_value_t<'q'> {};
struct r : char_value_t<'r'> {};
struct s : char_value_t<'s'> {};
struct t : char_value_t<'t'> {};
struct u : char_value_t<'u'> {};
struct v : char_value_t<'v'> {};
struct w : char_value_t<'w'> {};
struct x : char_value_t<'x'> {};
struct y : char_value_t<'y'> {};
struct z : char_value_t<'z'> {};
struct A : char_value_t<'A'> {};
struct B : char_value_t<'B'> {};
struct C : char_value_t<'C'> {};
struct D : char_value_t<'D'> {};
struct E : char_value_t<'E'> {};
struct F : char_value_t<'F'> {};
struct G : char_value_t<'G'> {};
struct H : char_value_t<'H'> {};
struct I : char_value_t<'I'> {};
struct J : char_value_t<'J'> {};
struct K : char_value_t<'K'> {};
struct L : char_value_t<'L'> {};
struct M : char_value_t<'M'> {};
struct N : char_value_t<'N'> {};
struct O : char_value_t<'O'> {};
struct P : char_value_t<'P'> {};
struct Q : char_value_t<'Q'> {};
struct R : char_value_t<'R'> {};
struct S : char_value_t<'S'> {};
struct T : char_value_t<'T'> {};
struct U : char_value_t<'U'> {};
struct V : char_value_t<'V'> {};
struct W : char_value_t<'W'> {};
struct X : char_value_t<'X'> {};
struct Y : char_value_t<'Y'> {};
struct Z : char_value_t<'Z'> {};
struct num_1 : char_value_t<'1'> {};
struct num_2 : char_value_t<'2'> {};
struct num_3 : char_value_t<'3'> {};
struct num_4 : char_value_t<'4'> {};
struct num_5 : char_value_t<'5'> {};
struct num_6 : char_value_t<'6'> {};
struct num_7 : char_value_t<'7'> {};
struct num_8 : char_value_t<'8'> {};
struct num_9 : char_value_t<'9'> {};
struct num_0 : char_value_t<'0'> {};
// SOMEWHAT SPECIAL CHARACTERS
struct bracket_open : char_value_t<'{'> {};
struct bracket_close : char_value_t<'}'> {};
struct underscore : char_value_t<'_'> {};

template<class Ty, class... Types>
concept is_any_of_t = std::disjunction_v<std::is_same<Ty, Types>...>;

template<typename Ty>
concept any_legit_char_t = is_any_of_t<Ty, a, b, c, d, e, f, g, h, i, j, k, l, m, n,
                                       o, p, q, r, s, t, u, v, w, x, y, z, A, B, C, D,
                                       E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T,
                                       U, V, W, X, Y, Z, num_1, num_2, num_3, num_4, num_5,
                                       num_6, num_7, num_8, num_9, num_0, bracket_open,
                                       bracket_close, underscore>;

template<class... values>
struct flag_t {
    [[nodiscard]] static constexpr size_t size() {
        return sizeof...(values);
    }

    template<typename Ty = char>
    [[nodiscard]] static constexpr Ty at(const std::size_t i) {
        constexpr char values_values[] = {values::value()...};
        return static_cast<Ty>(values_values[i]);
    }
};

template<size_t Footprint>
struct cxstring {
    char data[Footprint]{};
    [[nodiscard]] constexpr size_t size() const {
        return Footprint - 1;
    }
    constexpr /* implicit */ cxstring(const char (&init)[Footprint]) {// NOLINT
        std::copy_n(init, Footprint, data);
    }
};

template<auto str>
struct type_string {
    [[nodiscard]] static constexpr const char *data() {
        return str.data;
    }
    [[nodiscard]] static constexpr size_t size() {
        return str.size();
    }
};

template<class P>
auto parse_flag(P) -> P { return {}; }

template<char Chr, char... Rest, class... Bs>
auto parse_flag(flag_t<Bs...>) -> decltype(parse_flag<Rest...>(flag_t<Bs..., char_value_t<Chr>>{})) { return {}; }

template<class lambda_t, size_t... I>
constexpr auto make_flag(lambda_t lambda [[maybe_unused]], std::index_sequence<I...>) {
    return decltype(parse_flag<lambda()[I]...>(flag_t<>{})){};
}

template<cxstring str>
constexpr auto operator"" _flag() noexcept {
    constexpr auto s = type_string<str>{};
    return make_flag([&]() constexpr { return (s.data()); }, std::make_index_sequence<s.size()>{});
}

struct insn_t {
    uint32_t opcode = 0;
    uint32_t op0 = 0;
    uint32_t op1 = 0;
};

template<typename = std::monostate>
concept always_false_v = false;

template<insn_t>
concept always_false_insn_v = false;

template<flag_t Flag, insn_t... Instructions>
struct program_t {
    using R = std::array<uint32_t, 15>;

    template<insn_t Insn>
    static constexpr void execute_one(R &regs) {
        if constexpr (Insn.opcode == 0) {
            regs[Insn.op0] = Flag.at(Insn.op1);
        } else if constexpr (Insn.opcode == 1) {
            regs[Insn.op0] = Insn.op1;
        } else if constexpr (Insn.opcode == 2) {
            regs[Insn.op0] ^= Insn.op1;
        } else if constexpr (Insn.opcode == 3) {
            regs[Insn.op0] ^= regs[Insn.op1];
        } else if constexpr (Insn.opcode == 4) {
            regs[Insn.op0] |= Insn.op1;
        } else if constexpr (Insn.opcode == 5) {
            regs[Insn.op0] |= regs[Insn.op1];
        } else if constexpr (Insn.opcode == 6) {
            regs[Insn.op0] &= Insn.op1;
        } else if constexpr (Insn.opcode == 7) {
            regs[Insn.op0] &= regs[Insn.op1];
        } else if constexpr (Insn.opcode == 8) {
            regs[Insn.op0] += Insn.op1;
        } else if constexpr (Insn.opcode == 9) {
            regs[Insn.op0] += regs[Insn.op1];
        } else if constexpr (Insn.opcode == 10) {
            regs[Insn.op0] -= Insn.op1;
        } else if constexpr (Insn.opcode == 11) {
            regs[Insn.op0] -= regs[Insn.op1];
        } else if constexpr (Insn.opcode == 12) {
            regs[Insn.op0] *= Insn.op1;
        } else if constexpr (Insn.opcode == 13) {
            regs[Insn.op0] *= regs[Insn.op1];
        } else if constexpr (Insn.opcode == 14) {
            __noop;
        } else if constexpr (Insn.opcode == 15) {
            __noop;
            __noop;
        } else if constexpr (Insn.opcode == 16) {
            regs[Insn.op0] = rotr(regs[Insn.op0], Insn.op1);
        } else if constexpr (Insn.opcode == 17) {
            regs[Insn.op0] = rotr(regs[Insn.op0], regs[Insn.op1]);
        } else if constexpr (Insn.opcode == 18) {
            regs[Insn.op0] = rotl(regs[Insn.op0], Insn.op1);
        } else if constexpr (Insn.opcode == 19) {
            regs[Insn.op0] = rotl(regs[Insn.op0], regs[Insn.op1]);
        } else if constexpr (Insn.opcode == 20) {
            regs[Insn.op0] = regs[Insn.op1];
        } else if constexpr (Insn.opcode == 21) {
            regs[Insn.op0] = 0;
        } else if constexpr (Insn.opcode == 22) {
            regs[Insn.op0] >>= Insn.op1;
        } else if constexpr (Insn.opcode == 23) {
            regs[Insn.op0] >>= regs[Insn.op1];
        } else if constexpr (Insn.opcode == 24) {
            regs[Insn.op0] <<= Insn.op1;
        } else if constexpr (Insn.opcode == 25) {
            regs[Insn.op0] <<= regs[Insn.op1];
        } else {
            static_assert(always_false_insn_v<Insn>);
        }
    }

    template<std::size_t... Is>
    static constexpr void execute_impl(R &regs, std::index_sequence<Is...>) {
        (execute_one<Instructions>(regs), ...);
    }

    static constexpr void execute(R &regs) {
        execute_impl(regs, std::make_index_sequence<sizeof...(Instructions)>{});
    }

    static constexpr R registers = []() -> R {
        R arr = {};
        execute(arr);
        return arr;
    }();
};

int main() {
    /// Modify this text              vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
    [[maybe_unused]] auto flag = "HTB{___________________________________}"_flag;
    /// Modify this text              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    static_assert(decltype(flag)::size() == 40);

    using program = program_t<flag, insn_t(12, 13, 10), insn_t(21, 0, 0), insn_t(0, 13, 13), insn_t(0, 14, 0), insn_t(15, 11, 12), insn_t(24, 14, 0), insn_t(5, 0, 14), insn_t(0, 14, 1), insn_t(7, 11, 11), insn_t(24, 14, 8), insn_t(5, 0, 14), insn_t(0, 14, 2), insn_t(2, 10, 11), insn_t(24, 14, 16), insn_t(18, 12, 11), insn_t(5, 0, 14), insn_t(0, 14, 3), insn_t(0, 11, 11), insn_t(24, 14, 24), insn_t(13, 10, 10), insn_t(5, 0, 14), insn_t(2, 11, 13), insn_t(21, 1, 0), insn_t(0, 14, 4), insn_t(24, 14, 0), insn_t(5, 1, 14), insn_t(6, 11, 12), insn_t(0, 14, 5), insn_t(8, 10, 10), insn_t(24, 14, 8), insn_t(11, 12, 11), insn_t(5, 1, 14), insn_t(0, 14, 6), insn_t(0, 12, 10), insn_t(24, 14, 16), insn_t(9, 10, 13), insn_t(5, 1, 14), insn_t(0, 14, 7), insn_t(13, 12, 12), insn_t(24, 14, 24), insn_t(15, 10, 12), insn_t(5, 1, 14), insn_t(21, 2, 0), insn_t(20, 13, 13), insn_t(0, 14, 8), insn_t(24, 14, 0), insn_t(19, 10, 11), insn_t(5, 2, 14), insn_t(6, 12, 10), insn_t(0, 14, 9), insn_t(8, 11, 11), insn_t(24, 14, 8), insn_t(5, 2, 14), insn_t(0, 14, 10), insn_t(4, 11, 12), insn_t(24, 14, 16), insn_t(5, 2, 14), insn_t(0, 14, 11), insn_t(24, 14, 24), insn_t(4, 13, 12), insn_t(5, 2, 14), insn_t(21, 3, 0), insn_t(14, 10, 12), insn_t(0, 14, 12), insn_t(13, 10, 11), insn_t(24, 14, 0), insn_t(16, 10, 10), insn_t(5, 3, 14), insn_t(5, 11, 12), insn_t(0, 14, 13), insn_t(12, 10, 13), insn_t(24, 14, 8), insn_t(2, 10, 13), insn_t(5, 3, 14), insn_t(20, 11, 11), insn_t(0, 14, 14), insn_t(24, 14, 16), insn_t(18, 13, 11), insn_t(5, 3, 14), insn_t(6, 11, 13), insn_t(0, 14, 15), insn_t(24, 14, 24), insn_t(4, 11, 10), insn_t(5, 3, 14), insn_t(21, 4, 0), insn_t(15, 13, 11), insn_t(0, 14, 16), insn_t(6, 10, 10), insn_t(24, 14, 0), insn_t(14, 10, 12), insn_t(5, 4, 14), insn_t(0, 14, 17), insn_t(12, 13, 13), insn_t(24, 14, 8), insn_t(19, 11, 10), insn_t(5, 4, 14), insn_t(0, 14, 18), insn_t(17, 13, 12), insn_t(24, 14, 16), insn_t(5, 4, 14), insn_t(0, 14, 19), insn_t(24, 14, 24), insn_t(21, 12, 10), insn_t(5, 4, 14), insn_t(13, 13, 10), insn_t(21, 5, 0), insn_t(0, 14, 20), insn_t(19, 10, 13), insn_t(24, 14, 0), insn_t(5, 5, 14), insn_t(0, 14, 21), insn_t(24, 14, 8), insn_t(8, 13, 13), insn_t(5, 5, 14), insn_t(0, 14, 22), insn_t(16, 13, 11), insn_t(24, 14, 16), insn_t(10, 10, 13), insn_t(5, 5, 14), insn_t(7, 10, 12), insn_t(0, 14, 23), insn_t(19, 13, 10), insn_t(24, 14, 24), insn_t(5, 5, 14), insn_t(17, 12, 10), insn_t(21, 6, 0), insn_t(16, 11, 10), insn_t(0, 14, 24), insn_t(24, 14, 0), insn_t(10, 11, 10), insn_t(5, 6, 14), insn_t(0, 14, 25), insn_t(24, 14, 8), insn_t(7, 10, 12), insn_t(5, 6, 14), insn_t(0, 14, 26), insn_t(16, 12, 11), insn_t(24, 14, 16), insn_t(3, 11, 10), insn_t(5, 6, 14), insn_t(15, 11, 13), insn_t(0, 14, 27), insn_t(4, 12, 13), insn_t(24, 14, 24), insn_t(5, 6, 14), insn_t(14, 11, 13), insn_t(21, 7, 0), insn_t(0, 14, 28), insn_t(21, 13, 11), insn_t(24, 14, 0), insn_t(7, 12, 11), insn_t(5, 7, 14), insn_t(17, 11, 10), insn_t(0, 14, 29), insn_t(24, 14, 8), insn_t(5, 7, 14), insn_t(0, 14, 30), insn_t(12, 10, 10), insn_t(24, 14, 16), insn_t(5, 7, 14), insn_t(0, 14, 31), insn_t(20, 10, 10), insn_t(24, 14, 24), insn_t(5, 7, 14), insn_t(21, 8, 0), insn_t(18, 10, 12), insn_t(0, 14, 32), insn_t(9, 11, 11), insn_t(24, 14, 0), insn_t(21, 12, 11), insn_t(5, 8, 14), insn_t(0, 14, 33), insn_t(24, 14, 8), insn_t(19, 10, 13), insn_t(5, 8, 14), insn_t(8, 12, 13), insn_t(0, 14, 34), insn_t(24, 14, 16), insn_t(5, 8, 14), insn_t(8, 10, 10), insn_t(0, 14, 35), insn_t(24, 14, 24), insn_t(21, 13, 10), insn_t(5, 8, 14), insn_t(0, 12, 10), insn_t(21, 9, 0), insn_t(0, 14, 36), insn_t(24, 14, 0), insn_t(5, 9, 14), insn_t(17, 11, 11), insn_t(0, 14, 37), insn_t(14, 10, 13), insn_t(24, 14, 8), insn_t(5, 9, 14), insn_t(4, 10, 11), insn_t(0, 14, 38), insn_t(13, 11, 13), insn_t(24, 14, 16), insn_t(5, 9, 14), insn_t(0, 14, 39), insn_t(10, 11, 10), insn_t(24, 14, 24), insn_t(20, 13, 13), insn_t(5, 9, 14), insn_t(6, 12, 11), insn_t(21, 14, 0), insn_t(8, 0, 2769503260), insn_t(10, 0, 997841014), insn_t(19, 12, 11), insn_t(2, 0, 4065997671), insn_t(5, 13, 11), insn_t(8, 0, 690011675), insn_t(15, 11, 11), insn_t(8, 0, 540576667), insn_t(2, 0, 1618285201), insn_t(8, 0, 1123989331), insn_t(8, 0, 1914950564), insn_t(8, 0, 4213669998), insn_t(21, 13, 11), insn_t(8, 0, 1529621790), insn_t(10, 0, 865446746), insn_t(2, 10, 11), insn_t(8, 0, 449019059), insn_t(16, 13, 11), insn_t(8, 0, 906976959), insn_t(6, 10, 10), insn_t(8, 0, 892028723), insn_t(10, 0, 1040131328), insn_t(2, 0, 3854135066), insn_t(2, 0, 4133925041), insn_t(2, 0, 1738396966), insn_t(2, 12, 12), insn_t(8, 0, 550277338), insn_t(10, 0, 1043160697), insn_t(2, 1, 1176768057), insn_t(10, 1, 2368952475), insn_t(8, 12, 11), insn_t(2, 1, 2826144967), insn_t(8, 1, 1275301297), insn_t(10, 1, 2955899422), insn_t(2, 1, 2241699318), insn_t(12, 11, 10), insn_t(8, 1, 537794314), insn_t(11, 13, 10), insn_t(8, 1, 473021534), insn_t(17, 12, 13), insn_t(8, 1, 2381227371), insn_t(10, 1, 3973380876), insn_t(10, 1, 1728990628), insn_t(6, 11, 13), insn_t(8, 1, 2974252696), insn_t(0, 11, 11), insn_t(8, 1, 1912236055), insn_t(2, 1, 3620744853), insn_t(3, 10, 13), insn_t(2, 1, 2628426447), insn_t(11, 13, 12), insn_t(10, 1, 486914414), insn_t(16, 11, 12), insn_t(10, 1, 1187047173), insn_t(14, 12, 11), insn_t(2, 2, 3103274804), insn_t(13, 10, 10), insn_t(8, 2, 3320200805), insn_t(8, 2, 3846589389), insn_t(1, 13, 13), insn_t(2, 2, 2724573159), insn_t(10, 2, 1483327425), insn_t(2, 2, 1957985324), insn_t(14, 13, 12), insn_t(10, 2, 1467602691), insn_t(8, 2, 3142557962), insn_t(2, 13, 12), insn_t(2, 2, 2525769395), insn_t(8, 2, 3681119483), insn_t(8, 12, 11), insn_t(10, 2, 1041439413), insn_t(10, 2, 1042206298), insn_t(2, 2, 527001246), insn_t(20, 10, 13), insn_t(10, 2, 855860613), insn_t(8, 10, 10), insn_t(8, 2, 1865979270), insn_t(1, 13, 10), insn_t(8, 2, 2752636085), insn_t(2, 2, 1389650363), insn_t(10, 2, 2721642985), insn_t(18, 10, 11), insn_t(8, 2, 3276518041), insn_t(15, 10, 10), insn_t(2, 2, 1965130376), insn_t(2, 3, 3557111558), insn_t(2, 3, 3031574352), insn_t(16, 12, 10), insn_t(10, 3, 4226755821), insn_t(8, 3, 2624879637), insn_t(8, 3, 1381275708), insn_t(2, 3, 3310620882), insn_t(2, 3, 2475591380), insn_t(8, 3, 405408383), insn_t(2, 3, 2291319543), insn_t(0, 12, 12), insn_t(8, 3, 4144538489), insn_t(2, 3, 3878256896), insn_t(6, 11, 10), insn_t(10, 3, 2243529248), insn_t(10, 3, 561931268), insn_t(11, 11, 12), insn_t(10, 3, 3076955709), insn_t(18, 12, 13), insn_t(8, 3, 2019584073), insn_t(10, 13, 12), insn_t(8, 3, 1712479912), insn_t(18, 11, 11), insn_t(2, 3, 2804447380), insn_t(17, 10, 10), insn_t(10, 3, 2957126100), insn_t(18, 13, 13), insn_t(8, 3, 1368187437), insn_t(17, 10, 12), insn_t(8, 3, 3586129298), insn_t(10, 4, 1229526732), insn_t(19, 11, 11), insn_t(10, 4, 2759768797), insn_t(1, 10, 13), insn_t(2, 4, 2112449396), insn_t(10, 4, 1212917601), insn_t(2, 4, 1524771736), insn_t(8, 4, 3146530277), insn_t(2, 4, 2997906889), insn_t(16, 12, 10), insn_t(8, 4, 4135691751), insn_t(8, 4, 1960868242), insn_t(6, 12, 12), insn_t(10, 4, 2775657353), insn_t(16, 10, 13), insn_t(8, 4, 1451259226), insn_t(8, 4, 607382171), insn_t(13, 13, 13), insn_t(10, 4, 357643050), insn_t(2, 4, 2020402776), insn_t(8, 5, 2408165152), insn_t(13, 12, 10), insn_t(2, 5, 806913563), insn_t(10, 5, 772591592), insn_t(20, 13, 11), insn_t(2, 5, 2211018781), insn_t(10, 5, 2523354879), insn_t(8, 5, 2549720391), insn_t(2, 5, 3908178996), insn_t(2, 5, 1299171929), insn_t(8, 5, 512513885), insn_t(10, 5, 2617924552), insn_t(1, 12, 13), insn_t(8, 5, 390960442), insn_t(12, 11, 13), insn_t(8, 5, 1248271133), insn_t(8, 5, 2114382155), insn_t(1, 10, 13), insn_t(10, 5, 2078863299), insn_t(20, 12, 12), insn_t(8, 5, 2857504053), insn_t(10, 5, 4271947727), insn_t(2, 6, 2238126367), insn_t(2, 6, 1544827193), insn_t(8, 6, 4094800187), insn_t(2, 6, 3461906189), insn_t(10, 6, 1812592759), insn_t(2, 6, 1506702473), insn_t(8, 6, 536175198), insn_t(2, 6, 1303821297), insn_t(8, 6, 715409343), insn_t(2, 6, 4094566992), insn_t(14, 10, 11), insn_t(2, 6, 1890141105), insn_t(0, 13, 13), insn_t(2, 6, 3143319360), insn_t(10, 7, 696930856), insn_t(2, 7, 926450200), insn_t(8, 7, 352056373), insn_t(20, 13, 11), insn_t(10, 7, 3857703071), insn_t(8, 7, 3212660135), insn_t(5, 12, 10), insn_t(10, 7, 3854876250), insn_t(21, 12, 11), insn_t(8, 7, 3648688720), insn_t(2, 7, 2732629817), insn_t(4, 10, 12), insn_t(10, 7, 2285138643), insn_t(18, 10, 13), insn_t(2, 7, 2255852466), insn_t(2, 7, 2537336944), insn_t(3, 10, 13), insn_t(2, 7, 4257606405), insn_t(10, 8, 3703184638), insn_t(7, 11, 10), insn_t(10, 8, 2165056562), insn_t(8, 8, 2217220568), insn_t(19, 10, 12), insn_t(8, 8, 2088084496), insn_t(15, 13, 10), insn_t(8, 8, 443074220), insn_t(16, 13, 12), insn_t(10, 8, 1298336973), insn_t(2, 13, 11), insn_t(8, 8, 822378456), insn_t(19, 11, 12), insn_t(8, 8, 2154711985), insn_t(0, 11, 12), insn_t(10, 8, 430757325), insn_t(2, 12, 10), insn_t(2, 8, 2521672196), insn_t(10, 9, 532704100), insn_t(10, 9, 2519542932), insn_t(2, 9, 2451309277), insn_t(2, 9, 3957445476), insn_t(5, 10, 10), insn_t(8, 9, 2583554449), insn_t(10, 9, 1149665327), insn_t(12, 13, 12), insn_t(8, 9, 3053959226), insn_t(0, 10, 10), insn_t(8, 9, 3693780276), insn_t(15, 11, 10), insn_t(2, 9, 609918789), insn_t(2, 9, 2778221635), insn_t(16, 13, 10), insn_t(8, 9, 3133754553), insn_t(8, 11, 13), insn_t(8, 9, 3961507338), insn_t(2, 9, 1829237263), insn_t(16, 11, 13), insn_t(2, 9, 2472519933), insn_t(6, 12, 12), insn_t(8, 9, 4061630846), insn_t(10, 9, 1181684786), insn_t(13, 10, 11), insn_t(10, 9, 390349075), insn_t(8, 9, 2883917626), insn_t(10, 9, 3733394420), insn_t(10, 12, 12), insn_t(2, 9, 3895283827), insn_t(20, 10, 11), insn_t(2, 9, 2257053750), insn_t(10, 9, 2770821931), insn_t(18, 10, 13), insn_t(2, 9, 477834410), insn_t(19, 13, 12), insn_t(3, 0, 1), insn_t(12, 12, 12), insn_t(3, 1, 2), insn_t(11, 13, 11), insn_t(3, 2, 3), insn_t(3, 3, 4), insn_t(3, 4, 5), insn_t(1, 13, 13), insn_t(3, 5, 6), insn_t(7, 11, 11), insn_t(3, 6, 7), insn_t(4, 10, 12), insn_t(3, 7, 8), insn_t(18, 12, 12), insn_t(3, 8, 9), insn_t(21, 12, 10), insn_t(3, 9, 10)>;
    static_assert(program::registers[0] == 0x3ee88722 && program::registers[1] == 0xecbdbe2 && program::registers[2] == 0x60b843c4 && program::registers[3] == 0x5da67c7 && program::registers[4] == 0x171ef1e9 && program::registers[5] == 0x52d5b3f7 && program::registers[6] == 0x3ae718c0 && program::registers[7] == 0x8b4aacc2 && program::registers[8] == 0xe5cf78dd && program::registers[9] == 0x4a848edf && program::registers[10] == 0x8f && program::registers[11] == 0x4180000 && program::registers[12] == 0x0 && program::registers[13] == 0xd && program::registers[14] == 0x0, "Ah! Your flag is invalid.");
}

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$ g++ -std=c++20 -o main main.cpp
main.cpp: In function ‘int main()’:
main.cpp:284:41: error: static assertion failed: Ah! Your flag is invalid.
  284 |     static_assert(program::registers[0] == 0x3ee88722 && program::registers[1] == 0xecbdbe2 && program::registers[2] == 0x60b843c4 && program::registers[3] == 0x5da67c7 && program::registers[4] == 0x171ef1e9 && program::registers[5] == 0x52d5b3f7 && program::registers[6] == 0x3ae718c0 && program::registers[7] == 0x8b4aacc2 && program::registers[8] == 0xe5cf78dd && program::registers[9] == 0x4a848edf && program::registers[10] == 0x8f && program::registers[11] == 0x4180000 && program::registers[12] == 0x0 && program::registers[13] == 0xd && program::registers[14] == 0x0, "Ah! Your flag is invalid.");

컴파일해보면 static_assert에서 에러가 난다.

program::registers 값이 각 hex값과 같아지는 flag를 찾아야 한다.

solution

코드에 VM연산이 보기 쉽게 적혀있다.

emulator를 짜고 z3연산으로 바꿔줘서 플래그를 획득했다.

sol.py 

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from z3 import *

def parse(opcode, op0, op1):
    if opcode == 0:
        R[op0] = flag[op1]
    elif opcode == 1:
        R[op0] = BitVecVal(op1, 32)
    elif opcode == 2:
        R[op0] ^= op1
    elif opcode == 3:
        R[op0] ^= R[op1]
    elif opcode == 4:
        R[op0] |= op1
    elif opcode == 5:
        R[op0] |= R[op1]
    elif opcode == 6:
        R[op0] &= op1
    elif opcode == 7:
        R[op0] &= R[op1]
    elif opcode == 8:
        R[op0] += op1
    elif opcode == 9:
        R[op0] += R[op1]
    elif opcode == 10:
        R[op0] -= op1
    elif opcode == 11:
        R[op0] -= R[op1]
    elif opcode == 12:
        R[op0] *= op1
    elif opcode == 13:
        R[op0] *= R[op1]
    elif opcode == 16:
        R[op0] = RotateRight(R[op0], op1)
    elif opcode == 17:
        R[op0] = RotateRight(R[op0], R[op1])
    elif opcode == 18:
        R[op0] = RotateLeft(R[op0], op1)
    elif opcode == 19:
        R[op0] = RotateLeft(R[op0], R[op1])
    elif opcode == 20:
        R[op0] = R[op1]
    elif opcode == 21:
        R[op0] = BitVecVal(0, 32)
    elif opcode == 22:
        R[op0] = LShR(R[op0], op1)
    elif opcode == 23:
        R[op0] = LShR(R[op0], R[op1])
    elif opcode == 24:
        R[op0] = (R[op0] << op1) & 0xffffffff
    elif opcode == 25:
        R[op0] = (R[op0] << R[op1]) & 0xffffffff        

    R[op0] &= 0xffffffff

opcodes = [[12, 13, 10], [21, 0, 0], [0, 13, 13], [0, 14, 0], [15, 11, 12], [24, 14, 0], [5, 0, 14], [0, 14, 1], [7, 11, 11], [24, 14, 8], [5, 0, 14], [0, 14, 2], [2, 10, 11], [24, 14, 16], [18, 12, 11], [5, 0, 14], [0, 14, 3], [0, 11, 11], [24, 14, 24], [13, 10, 10], [5, 0, 14], [2, 11, 13], [21, 1, 0], [0, 14, 4], [24, 14, 0], [5, 1, 14], [6, 11, 12], [0, 14, 5], [8, 10, 10], [24, 14, 8], [11, 12, 11], [5, 1, 14], [0, 14, 6], [0, 12, 10], [24, 14, 16], [9, 10, 13], [5, 1, 14], [0, 14, 7], [13, 12, 12], [24, 14, 24], [15, 10, 12], [5, 1, 14], [21, 2, 0], [20, 13, 13], [0, 14, 8], [24, 14, 0], [19, 10, 11], [5, 2, 14], [6, 12, 10], [0, 14, 9], [8, 11, 11], [24, 14, 8], [5, 2, 14], [0, 14, 10], [4, 11, 12], [24, 14, 16], [5, 2, 14], [0, 14, 11], [24, 14, 24], [4, 13, 12], [5, 2, 14], [21, 3, 0], [14, 10, 12], [0, 14, 12], [13, 10, 11], [24, 14, 0], [16, 10, 10], [5, 3, 14], [5, 11, 12], [0, 14, 13], [12, 10, 13], [24, 14, 8], [2, 10, 13], [5, 3, 14], [20, 11, 11], [0, 14, 14], [24, 14, 16], [18, 13, 11], [5, 3, 14], [6, 11, 13], [0, 14, 15], [24, 14, 24], [4, 11, 10], [5, 3, 14], [21, 4, 0], [15, 13, 11], [0, 14, 16], [6, 10, 10], [24, 14, 0], [14, 10, 12], [5, 4, 14], [0, 14, 17], [12, 13, 13], [24, 14, 8], [19, 11, 10], [5, 4, 14], [0, 14, 18], [17, 13, 12], [24, 14, 16], [5, 4, 14], [0, 14, 19], [24, 14, 24], [21, 12, 10], [5, 4, 14], [13, 13, 10], [21, 5, 0], [0, 14, 20], [19, 10, 13], [24, 14, 0], [5, 5, 14], [0, 14, 21], [24, 14, 8], [8, 13, 13], [5, 5, 14], [0, 14, 22], [16, 13, 11], [24, 14, 16], [10, 10, 13], [5, 5, 14], [7, 10, 12], [0, 14, 23], [19, 13, 10], [24, 14, 24], [5, 5, 14], [17, 12, 10], [21, 6, 0], [16, 11, 10], [0, 14, 24], [24, 14, 0], [10, 11, 10], [5, 6, 14], [0, 14, 25], [24, 14, 8], [7, 10, 12], [5, 6, 14], [0, 14, 26], [16, 12, 11], [24, 14, 16], [3, 11, 10], [5, 6, 14], [15, 11, 13], [0, 14, 27], [4, 12, 13], [24, 14, 24], [5, 6, 14], [14, 11, 13], [21, 7, 0], [0, 14, 28], [21, 13, 11], [24, 14, 0], [7, 12, 11], [5, 7, 14], [17, 11, 10], [0, 14, 29], [24, 14, 8], [5, 7, 14], [0, 14, 30], [12, 10, 10], [24, 14, 16], [5, 7, 14], [0, 14, 31], [20, 10, 10], [24, 14, 24], [5, 7, 14], [21, 8, 0], [18, 10, 12], [0, 14, 32], [9, 11, 11], [24, 14, 0], [21, 12, 11], [5, 8, 14], [0, 14, 33], [24, 14, 8], [19, 10, 13], [5, 8, 14], [8, 12, 13], [0, 14, 34], [24, 14, 16], [5, 8, 14], [8, 10, 10], [0, 14, 35], [24, 14, 24], [21, 13, 10], [5, 8, 14], [0, 12, 10], [21, 9, 0], [0, 14, 36], [24, 14, 0], [5, 9, 14], [17, 11, 11], [0, 14, 37], [14, 10, 13], [24, 14, 8], [5, 9, 14], [4, 10, 11], [0, 14, 38], [13, 11, 13], [24, 14, 16], [5, 9, 14], [0, 14, 39], [10, 11, 10], [24, 14, 24], [20, 13, 13], [5, 9, 14], [6, 12, 11], [21, 14, 0], [8, 0, 2769503260], [10, 0, 997841014], [19, 12, 11], [2, 0, 4065997671], [5, 13, 11], [8, 0, 690011675], [15, 11, 11], [8, 0, 540576667], [2, 0, 1618285201], [8, 0, 1123989331], [8, 0, 1914950564], [8, 0, 4213669998], [21, 13, 11], [8, 0, 1529621790], [10, 0, 865446746], [2, 10, 11], [8, 0, 449019059], [16, 13, 11], [8, 0, 906976959], [6, 10, 10], [8, 0, 892028723], [10, 0, 1040131328], [2, 0, 3854135066], [2, 0, 4133925041], [2, 0, 1738396966], [2, 12, 12], [8, 0, 550277338], [10, 0, 1043160697], [2, 1, 1176768057], [10, 1, 2368952475], [8, 12, 11], [2, 1, 2826144967], [8, 1, 1275301297], [10, 1, 2955899422], [2, 1, 2241699318], [12, 11, 10], [8, 1, 537794314], [11, 13, 10], [8, 1, 473021534], [17, 12, 13], [8, 1, 2381227371], [10, 1, 3973380876], [10, 1, 1728990628], [6, 11, 13], [8, 1, 2974252696], [0, 11, 11], [8, 1, 1912236055], [2, 1, 3620744853], [3, 10, 13], [2, 1, 2628426447], [11, 13, 12], [10, 1, 486914414], [16, 11, 12], [10, 1, 1187047173], [14, 12, 11], [2, 2, 3103274804], [13, 10, 10], [8, 2, 3320200805], [8, 2, 3846589389], [1, 13, 13], [2, 2, 2724573159], [10, 2, 1483327425], [2, 2, 1957985324], [14, 13, 12], [10, 2, 1467602691], [8, 2, 3142557962], [2, 13, 12], [2, 2, 2525769395], [8, 2, 3681119483], [8, 12, 11], [10, 2, 1041439413], [10, 2, 1042206298], [2, 2, 527001246], [20, 10, 13], [10, 2, 855860613], [8, 10, 10], [8, 2, 1865979270], [1, 13, 10], [8, 2, 2752636085], [2, 2, 1389650363], [10, 2, 2721642985], [18, 10, 11], [8, 2, 3276518041], [15, 10, 10], [2, 2, 1965130376], [2, 3, 3557111558], [2, 3, 3031574352], [16, 12, 10], [10, 3, 4226755821], [8, 3, 2624879637], [8, 3, 1381275708], [2, 3, 3310620882], [2, 3, 2475591380], [8, 3, 405408383], [2, 3, 2291319543], [0, 12, 12], [8, 3, 4144538489], [2, 3, 3878256896], [6, 11, 10], [10, 3, 2243529248], [10, 3, 561931268], [11, 11, 12], [10, 3, 3076955709], [18, 12, 13], [8, 3, 2019584073], [10, 13, 12], [8, 3, 1712479912], [18, 11, 11], [2, 3, 2804447380], [17, 10, 10], [10, 3, 2957126100], [18, 13, 13], [8, 3, 1368187437], [17, 10, 12], [8, 3, 3586129298], [10, 4, 1229526732], [19, 11, 11], [10, 4, 2759768797], [1, 10, 13], [2, 4, 2112449396], [10, 4, 1212917601], [2, 4, 1524771736], [8, 4, 3146530277], [2, 4, 2997906889], [16, 12, 10], [8, 4, 4135691751], [8, 4, 1960868242], [6, 12, 12], [10, 4, 2775657353], [16, 10, 13], [8, 4, 1451259226], [8, 4, 607382171], [13, 13, 13], [10, 4, 357643050], [2, 4, 2020402776], [8, 5, 2408165152], [13, 12, 10], [2, 5, 806913563], [10, 5, 772591592], [20, 13, 11], [2, 5, 2211018781], [10, 5, 2523354879], [8, 5, 2549720391], [2, 5, 3908178996], [2, 5, 1299171929], [8, 5, 512513885], [10, 5, 2617924552], [1, 12, 13], [8, 5, 390960442], [12, 11, 13], [8, 5, 1248271133], [8, 5, 2114382155], [1, 10, 13], [10, 5, 2078863299], [20, 12, 12], [8, 5, 2857504053], [10, 5, 4271947727], [2, 6, 2238126367], [2, 6, 1544827193], [8, 6, 4094800187], [2, 6, 3461906189], [10, 6, 1812592759], [2, 6, 1506702473], [8, 6, 536175198], [2, 6, 1303821297], [8, 6, 715409343], [2, 6, 4094566992], [14, 10, 11], [2, 6, 1890141105], [0, 13, 13], [2, 6, 3143319360], [10, 7, 696930856], [2, 7, 926450200], [8, 7, 352056373], [20, 13, 11], [10, 7, 3857703071], [8, 7, 3212660135], [5, 12, 10], [10, 7, 3854876250], [21, 12, 11], [8, 7, 3648688720], [2, 7, 2732629817], [4, 10, 12], [10, 7, 2285138643], [18, 10, 13], [2, 7, 2255852466], [2, 7, 2537336944], [3, 10, 13], [2, 7, 4257606405], [10, 8, 3703184638], [7, 11, 10], [10, 8, 2165056562], [8, 8, 2217220568], [19, 10, 12], [8, 8, 2088084496], [15, 13, 10], [8, 8, 443074220], [16, 13, 12], [10, 8, 1298336973], [2, 13, 11], [8, 8, 822378456], [19, 11, 12], [8, 8, 2154711985], [0, 11, 12], [10, 8, 430757325], [2, 12, 10], [2, 8, 2521672196], [10, 9, 532704100], [10, 9, 2519542932], [2, 9, 2451309277], [2, 9, 3957445476], [5, 10, 10], [8, 9, 2583554449], [10, 9, 1149665327], [12, 13, 12], [8, 9, 3053959226], [0, 10, 10], [8, 9, 3693780276], [15, 11, 10], [2, 9, 609918789], [2, 9, 2778221635], [16, 13, 10], [8, 9, 3133754553], [8, 11, 13], [8, 9, 3961507338], [2, 9, 1829237263], [16, 11, 13], [2, 9, 2472519933], [6, 12, 12], [8, 9, 4061630846], [10, 9, 1181684786], [13, 10, 11], [10, 9, 390349075], [8, 9, 2883917626], [10, 9, 3733394420], [10, 12, 12], [2, 9, 3895283827], [20, 10, 11], [2, 9, 2257053750], [10, 9, 2770821931], [18, 10, 13], [2, 9, 477834410], [19, 13, 12], [3, 0, 1], [12, 12, 12], [3, 1, 2], [11, 13, 11], [3, 2, 3], [3, 3, 4], [3, 4, 5], [1, 13, 13], [3, 5, 6], [7, 11, 11], [3, 6, 7], [4, 10, 12], [3, 7, 8], [18, 12, 12], [3, 8, 9], [21, 12, 10], [3, 9, 10]]

s = Solver()

R = [BitVec(f'REG{i}', 32) for i in range(15)]
target = [0x3ee88722, 0xecbdbe2, 0x60b843c4, 0x5da67c7, 0x171ef1e9, 0x52d5b3f7, 0x3ae718c0, 0x8b4aacc2, 0xe5cf78dd, 0x4a848edf, 0x8f, 0x4180000, 0x0, 0xd, 0x0]
flag = [BitVec(f'flag{i}', 32) for i in range(40)]
orig_flag = [c for c in flag]

for c in orig_flag:
    s.add(And(0x20 <= c,c <= 0x7f))

for opcode in opcodes:
    parse(*opcode)

for i in range(15):
    s.add(R[i] == target[i])

assert s.check() == sat

m = s.model()
print(''.join([chr(m[x].as_long()) for x in orig_flag]))

flag : HTB{m4n_1_l0v4_cXX_TeMpl4t35_9fb60c17b0}

MazeOfPower - 350pts

solver 짜던 중에 팀원 분이 먼저 풀어서 나중에 다시 풀었다..ㅎ

main이 주어지고 remote로 풀어야 한다.

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$ file main
main: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=246eec7fd33acbeba185edfe290af7cb632dec84, for GNU/Linux 3.2.0, with debug_info, not stripped

main 

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// main.main
// local variable allocation has failed, the output may be wrong!
void __fastcall main_main()
{
  __int128 v0; // xmm15
  __int64 v1; // rax
  __int64 v2; // rbx
  __int64 v3; // rbp
  void *v4; // rax
  __int64 v5; // rbp
  __int64 v6; // rax
  int v7; // rcx OVERLAPPED
  _slice_int *v8; // rdx
  int v9; // rbx
  int *v10; // rax
  _slice_int *v11; // rax
  __int64 v12; // rsi
  int **v13; // r11
  maze_Point *p_maze_Point; // rax
  maze_Point *v15; // rax
  uint8 *str; // rax
  char v17; // dl
  int i; // rax
  uint8 *v19; // rax
  main_keyDir *v20; // r9
  __int64 *v21; // [rsp+0h] [rbp-310h]
  _BYTE v22[71]; // [rsp+10h] [rbp-300h] BYREF
  char v23[25]; // [rsp+57h] [rbp-2B9h] BYREF
  int oldCap; // [rsp+70h] [rbp-2A0h]
  const char *t; // [rsp+78h] [rbp-298h]
  time_Time v26; // [rsp+80h] [rbp-290h]
  _slice_int *v27; // [rsp+98h] [rbp-278h]
  github_com_redpwn_pow_Challenge *c; // [rsp+A0h] [rbp-270h]
  __m256 v29; // [rsp+A8h] [rbp-268h] BYREF
  __int128 v30; // [rsp+C8h] [rbp-248h] BYREF
  github_com_itchyny_maze_Format format; // [rsp+D8h] [rbp-238h] BYREF
  github_com_itchyny_maze_Maze maze; // [rsp+1E8h] [rbp-128h] BYREF
  __int128 v33; // [rsp+230h] [rbp-E0h] BYREF
  __int64 v34; // [rsp+240h] [rbp-D0h]
  RTYPE **v35; // [rsp+248h] [rbp-C8h]
  _ptr_os_File v36; // [rsp+250h] [rbp-C0h]
  __int64 v37; // [rsp+278h] [rbp-98h]
  __int64 v38; // [rsp+280h] [rbp-90h]
  bufio_Reader b; // [rsp+288h] [rbp-88h] BYREF
  _slice_interface_ a; // [rsp+2E0h] [rbp-30h] BYREF
  int *v41; // [rsp+2F8h] [rbp-18h]
  _ptr_os_File v42; // [rsp+300h] [rbp-10h]
  __int64 v43; // [rsp+308h] [rbp-8h] BYREF
  _slice_interface_ v44; // 0:rsi.24
  io_Writer v45; // 0:rax.8,8:rbx.8
  string v46; // 0:rax.8,8:rbx.8
  string v47; // 0:rax.8,8:rbx.8
  string v48; // 0:rax.8,8:rbx.8
  string v49; // 0:rcx.8,8:rdi.8 OVERLAPPED
  _slice_interface_ v50; // 0:rcx.8,8:rdi.16
  _slice_interface_ v51; // 0:rcx.8,8:rdi.16
  _slice_interface_ v52; // 0:rcx.8,8:rdi.16
  string v53; // 0:rbx.8,8:rcx.8
  string pow_str; // 0:rbx.8,8:rcx.8
  string v55; // 0:rbx.8,8:rcx.8
  string v56; // 0:rbx.8,8:rcx.8
  retval_4B59E0 v57; // 0:al.1,8:rbx.8,16:rcx.8
  _slice_uint8 pow; // 0:rax.8,8:rbx.8,16:rcx.8
  time_Time v59; // 0:rax.8,8:rbx.8,16:rcx.8
  time_Time v60; // 0:rax.8,8:rbx.8,16:rcx.8
  _slice_uint8_0 v61; // 0:rbx.8,8:rcx.8,16:rdi.8 OVERLAPPED

  c = github_com_redpwn_pow_GenerateChallenge(0x1388u);
  a.array = (interface_ *)&RTYPE__ptr_pow_Challenge;
  a.len = (int)c;
  v45.data = os_Stdout;
  v49.str = (uint8 *)"proof of work: curl -sSfL https://pwn.red/pow | sh -s %s\nsolution";
  v49.len = 67LL;
  v44.array = (interface_ *)&a;
  v44.len = 1LL;
  v44.cap = 1LL;
  v45.tab = (runtime_itab *)&go_itab__ptr_os_File_comma_io_Writer;
  *(retval_4957E0 *)&v49.str = fmt_Fprintf(v45, v49, v44);
  v42 = os_Stdin;
  *(_OWORD *)&b.buf.array = v0;
  v21 = &v43;
  ((void (__golang *)(__int64, __int64, _ptr_os_File, _BYTE *))loc_46AEF0)(v1, v2, os_Stdin, &v22[592]);
  v3 = (__int64)v21;
  v4 = runtime_makeslice((internal_abi_Type *)&RTYPE_uint8_0, 4096LL, 4096LL);
  v33 = v0;
  v21 = (__int64 *)v3;
  *(_QWORD *)&v33 = ((__int64 (__golang *)(void *, __int64, uint8 *, _BYTE *))loc_46AEF0)(
                      v4,
                      4096LL,
                      v49.str,
                      &v22[504]);
  *((_QWORD *)&v33 + 1) = 4096LL;
  v34 = 4096LL;
  v35 = go_itab__ptr_os_File_comma_io_Reader;
  v36 = v42;
  v37 = -1LL;
  v38 = -1LL;
  b.buf.array = (uint8 *)v33;
  ((void (__fastcall *)(int *, char *))loc_46B25A)(&b.buf.len, (char *)&v33 + 8);
  v5 = (__int64)v21;
  v26.loc = (time_Location *)bufio__ptr_Reader_ReadString(&b, 0xAu);
  *(_QWORD *)&v23[9] = 10LL;
  v53.len = 10LL;
  v53.str = (uint8 *)v26.loc;
  v57 = github_com_redpwn_pow__ptr_Challenge_Check(c, v53);
  if ( !v57._r1.tab && v57._r0 )
  {
    pow_str.str = (uint8 *)v26.loc;
    pow_str.len = *(_QWORD *)&v23[9];
    pow = runtime_stringtoslicebyte(0LL, pow_str);
    LODWORD(pow.array) = hash_crc32_ChecksumIEEE(pow);
    math_rand_Seed(LODWORD(pow.array));
    v6 = 0LL;
    v7 = 0LL;
    v8 = 0LL;
    v9 = 0LL;
    while ( v6 < 25 )
    {
      *(_QWORD *)&v23[1] = v6;
      oldCap = v7;
      v27 = v8;
      *(_QWORD *)&v23[17] = v9;
      v10 = (int *)runtime_makeslice((internal_abi_Type *)&RTYPE_int_0, 50LL, 50LL);
      v9 = *(_QWORD *)&v23[17] + 1LL;
      v7 = oldCap;
      if ( oldCap < (unsigned __int64)(*(_QWORD *)&v23[17] + 1LL) )
      {
        v41 = v10;
        *(runtime_slice *)(&v7 - 2) = runtime_growslice(v27, v9, oldCap, 1LL, (internal_abi_Type *)&RTYPE__slice_int_0);
        v8 = v11;
        v10 = v41;
      }
      else
      {
        v8 = v27;
      }
      v12 = v9;
      v8[v12 - 1].len = 50LL;
      v8[v12 - 1].cap = 50LL;
      if ( *(_DWORD *)&runtime_writeBarrier.enabled )
      {
        runtime_gcWriteBarrier2();
        *v13 = v10;
        v13[1] = v8[v9 - 1].array;
      }
      v8[v9 - 1].array = v10;
      v6 = *(_QWORD *)&v23[1] + 1LL;
    }
    *(_OWORD *)&maze.Start = v0;
    *(_OWORD *)&maze.Cursor = v0;
    maze.Directions.len = v9;
    maze.Directions.cap = v7;
    maze.Directions.array = v8;
    maze.Height = 25LL;
    maze.Width = 50LL;
    maze.Start = (github_com_itchyny_maze_Point *)runtime_newobject((internal_abi_Type *)&RTYPE_maze_Point);
    p_maze_Point = (maze_Point *)runtime_newobject((internal_abi_Type *)&RTYPE_maze_Point);
    p_maze_Point->X = 24LL;
    p_maze_Point->Y = 49LL;
    maze.Goal = (github_com_itchyny_maze_Point *)p_maze_Point;
    maze.Cursor = (github_com_itchyny_maze_Point *)runtime_newobject((internal_abi_Type *)&RTYPE_maze_Point);
    maze.Solved = 0;
    maze.Started = 0;
    maze.Finished = 0;
    maze.Start = (github_com_itchyny_maze_Point *)runtime_newobject((internal_abi_Type *)&RTYPE_maze_Point);
    v15 = (maze_Point *)runtime_newobject((internal_abi_Type *)&RTYPE_maze_Point);
    v15->X = maze.Height - 1;
    v15->Y = maze.Width - 1;
    maze.Goal = (github_com_itchyny_maze_Point *)v15;
    maze.Cursor = maze.Start;
    github_com_itchyny_maze__ptr_Maze_Generate(&maze);
    v21 = (__int64 *)v5;
    ((void (__fastcall *)(_BYTE *))loc_46AEAB)(&v22[152]);
    format.Wall.len = 2LL;
    format.Wall.str = (uint8 *)"  "; // 벽 안 보임
    format.Path.len = 2LL;
    format.Path.str = (uint8 *)"  ";
    format.StartLeft.len = 2LL;
    format.StartLeft.str = (uint8 *)"SS";
    format.StartRight.len = 2LL;
    format.StartRight.str = (uint8 *)"SS";
    format.GoalLeft.len = 2LL;
    format.GoalLeft.str = (uint8 *)"EE";
    format.GoalRight.len = 2LL;
    format.GoalRight.str = (uint8 *)"EE";
    format.Solution.len = 2LL;
    format.Solution.str = (uint8 *)"::";
    format.SolutionStartLeft.len = 2LL;
    format.SolutionStartLeft.str = (uint8 *)"SS";
    format.SolutionStartRight.len = 2LL;
    format.SolutionStartRight.str = (uint8 *)"SS";
    format.SolutionGoalLeft.len = 2LL;
    format.SolutionGoalLeft.str = (uint8 *)"EE";
    format.SolutionGoalRight.len = 2LL;
    format.SolutionGoalRight.str = (uint8 *)"EE";
    format.Visited.len = 2LL;
    format.Visited.str = (uint8 *)"  ";
    format.VisitedStartLeft.len = 2LL;
    format.VisitedStartLeft.str = (uint8 *)"SS";
    format.VisitedStartRight.len = 2LL;
    format.VisitedStartRight.str = (uint8 *)"SS";
    format.VisitedGoalLeft.len = 2LL;
    format.VisitedGoalLeft.str = (uint8 *)"EE";
    format.VisitedGoalRight.len = 2LL;
    format.VisitedGoalRight.str = (uint8 *)"EE";
    format.Cursor.len = 2LL;
    format.Cursor.str = (uint8 *)"::";
    v26.ext = (int64)time_NewTicker(10000000LL);
    v59 = time_Now();
    v26.wall = v59.wall;
    t = "EE";
    a.cap = (int)v59.loc;
    maze.Started = 1;
    str = github_com_itchyny_maze__ptr_Maze_String(&maze, &format).str;
    v30 = v0;
    v55.len = 61LL;
    v50.len = (int)str;
    v50.cap = (int)&format;
    v55.str = (uint8 *)"Can you solve my maze within 20 seconds?\nControls: q/k/j/h/l\n";
    v46 = runtime_concatstring2(0LL, v55, *(string *)&v50.len);
    v46.str = (uint8 *)runtime_convTstring(v46);
    *(_QWORD *)&v30 = &RTYPE_string_0;
    *((_QWORD *)&v30 + 1) = v46.str;
    v46.len = (int)os_Stdout;
    v46.str = (uint8 *)&go_itab__ptr_os_File_comma_io_Writer;
    v50.len = 1LL;
    v50.cap = 1LL;
    v50.array = (interface_ *)&v30;
    fmt_Fprintln((io_Writer)v46, v50);
    while ( 1 )
    {
      do
      {
LABEL_13:
        v23[0] = 0;
        v61.ptr = (uint8_0 *)v23;
        v61.len = 1LL;
        v61.cap = 1LL;
        v61 = (_slice_uint8_0)os__ptr_File_Read(os_Stdin, v61);
      }
      while ( v61.ptr );
      v17 = v23[0];
      if ( (unsigned __int8)(v23[0] - 'A') <= 0x19u )
        v17 = v23[0] + ' ';
      if ( !maze.Finished )
      {
        for ( i = 0LL; i < main_keyDirs.len; ++i )
        {
          v20 = main_keyDirs.array[i];
          if ( v20->char == v17 )
          {
            github_com_itchyny_maze__ptr_Maze_Move(&maze, v20->dir);
            if ( maze.Finished )
              github_com_itchyny_maze__ptr_Maze_Solve(&maze);
            v19 = github_com_itchyny_maze__ptr_Maze_String(&maze, &format).str;
            *(_OWORD *)&v29.m256_f32[4] = v0;
            v56.len = 61LL;
            v51.len = (int)v19;
            v51.cap = (int)&format;
            v56.str = (uint8 *)"Can you solve my maze within 20 seconds?\nControls: q/k/j/h/l\n";
            v47 = runtime_concatstring2(0LL, v56, *(string *)&v51.len);
            v47.str = (uint8 *)runtime_convTstring(v47);
            *(_QWORD *)&v29.m256_f32[4] = &RTYPE_string_0;
            *(_QWORD *)&v29.m256_f32[6] = v47.str;
            v47.len = (int)os_Stdout;
            v47.str = (uint8 *)&go_itab__ptr_os_File_comma_io_Writer;
            v51.len = 1LL;
            v51.cap = 1LL;
            v51.array = (interface_ *)&v29.m256_f32[4];
            fmt_Fprintln((io_Writer)v47, v51);
            if ( maze.Finished )
            {
              v60.wall = v26.wall;
              v60.ext = (int64)t;
              v60.loc = (time_Location *)a.cap;
              v60.wall = time_Since(v60);
              main_printFinished(&maze, v60.wall); // prints flag
            }
            goto LABEL_13;
          }
        }
      }
      if ( v17 == 'q' )
        break;
      if ( v17 == 'b' )
      {
        github_com_itchyny_maze__ptr_Maze_Solve(&maze);
        maze.Finished = 1;
        v48 = github_com_itchyny_maze__ptr_Maze_String(&maze, &format);
        *(_OWORD *)v29.m256_f32 = v0;
        v48.str = (uint8 *)runtime_convTstring(v48);
        *(_QWORD *)v29.m256_f32 = &RTYPE_string_0;
        *(_QWORD *)&v29.m256_f32[2] = v48.str;
        v48.len = (int)os_Stdout;
        v48.str = (uint8 *)&go_itab__ptr_os_File_comma_io_Writer;
        v52.len = 1LL;
        v52.cap = 1LL;
        v52.array = (interface_ *)&v29;
        fmt_Fprintln((io_Writer)v48, v52);
      }
    }
    time_stopTimer((runtime_timer *)(v26.ext + 8));
  }
}

https://github.com/itchyny/maze/blob/main/maze.go를 사용한다.

분석해보면 k, j, h, l이 방향키고 20초 안에 미로를 통과하면 flag를 출력한다.

b를 누르면 maze의 solution이 출력되지만 maze.Finished = 1로 설정돼서

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if ( maze.Finished )
{
    v60.wall = v26.wall;
    v60.ext = (int64)t;
    v60.loc = (time_Location *)a.cap;
    v60.wall = time_Since(v60);
    main_printFinished(&maze, v60.wall); // prints flag
}

여기 있는 flag 출력 로직으로 갈 수가 없다.

solution

main에서 보면

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v53.str = (uint8 *)v26.loc;
v57 = github_com_redpwn_pow__ptr_Challenge_Check(c, v53);
if ( !v57._r1.tab && v57._r0 )
{
    v54.str = (uint8 *)v26.loc;
    v54.len = *(_QWORD *)&v23[9];
    v58 = runtime_stringtoslicebyte(0LL, v54);
    LODWORD(v58.array) = hash_crc32_ChecksumIEEE(v58);
    math_rand_Seed(LODWORD(v58.array));
    ...

crc32(PoW)를 seed로 사용한다.

github 코드를 보면 math/rand를 이용해 random한 maze를 생성하기 때문에 PoW 값으로 remote 환경의 maze를 얻을 수 있다.

https://github.com/itchyny/maze/blob/main/maze.go#L141로 maze의 solution을 얻을 수 있어서 아래 코드를 작성했다.

get_maze.go 

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package main

import (
    "fmt"
    "hash/crc32"
    "math/rand"
    "github.com/itchyny/maze"
)

func main() {
    var input string
    fmt.Scanln(&input) // PoW 입력
    input += "\n"
    inputBytes := []byte(input)

    hash := crc32.ChecksumIEEE(inputBytes)
    rand.Seed(int64(hash))

    m := maze.NewMaze(25, 50)
    m.Generate()
    m.Solve()
    fmt.Println(m.String(maze.Default))
}

이제 maze의 solution을 얻을 수 있으니 서버로 path를 보내주는 코드만 작성하면 된다.

sol.py 

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'''
h : left
j : down
k : up
l : right
q : quit
b : solve -> prints answer. if once it called, cannot get flag
if ( !maze.Finished ) // blocked here
      {
        for ( i = 0LL; i < main_keyDirs.len; ++i )
'''

import subprocess
from pwn import *

def solve(PoW):
    r = process(['go', 'run', '.'])
    r.sendline(PoW)
    lines = r.recvall().decode().split('\n')[2:-4]

    maze = [[] for _ in range(len(lines))]
    for i, line in enumerate(lines):
        for j in range(2, len(line), 2):
            maze[i].append(line[j:j+2])

    dx = [1, 0, -1, 0]
    dy = [0, 1, 0, -1]
    dd = ['l', 'j', 'h', 'k']

    cur = [0, 1] # y, x
    path = []
    while 1:
        if cur == [48, 99]:
            break

        for i in range(4):
            nx = cur[1] + dx[i]
            ny = cur[0] + dy[i]

            if nx < 0 or nx >= 100 or ny < 0 or ny >= 49:
                continue

            if maze[ny][nx] != '::':
                continue

            path.append(dd[i])
            maze[ny][nx] = '  '
            nx += dx[i]
            ny += dy[i]
            maze[ny][nx] = '  '
            cur = [ny, nx]
            break

    return path


# p = process('./main')
p = remote('83.136.249.138', 33145)

result = subprocess.run(p.recvlineS().split("proof of work:")[1], shell=True, capture_output=True, text=True)
p.sendlineafter('solution:', result.stdout)

ans = solve(result.stdout)
p.sendline(''.join(ans))

p.interactive()

flag : HTB{by_th3_p0w3r_0f_th3_m4z3!!1}

리모트로 풀어야 돼서 전혀 생각도 안 했는데 팀원은 코드 패치해서 풀었다.

PoW 확인하는 부분만 패치하면 b로 solution을 얻을 수 있어서 훨씬 편하다..

후기

학교 다니느라 평일에 많이 못 참여할까봐 걱정했는데

걱정이 무색하게 팀원들이 15시간만에 올클해버렸다 :joy:

이번에 연합팀으로 해보니 숙련도 차이로 리버싱이나 코드 작성할 때 잘하는 사람들이랑 시간 차이가 많이 나는 거 같다.

앞으로 리버싱 많이 해야겠다..!

2024, HackTheBox
This post is licensed under CC BY 4.0 by the author.
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