[原创]第二题星际生物-CTF对抗-看雪-安全社区|安全招聘|kanxue.com

[原创]第二题星际生物

发表于: 2024-8-17 00:03 1284

[原创]第二题星际生物

mb_wvlcywyp 活跃值

2024-8-17 00:03

1284

题目是一个数独加一个迷宫

文件类型：PE32+ executable (console) x86-64 Mono/.Net assembly, for MS Windows

核心函数：

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// Token: 0x06000003 RID: 3 RVA: 0x00001090 File Offset: 0x00000490
internal unsafe static int main()
{
    $ArrayType$$$BY0BAA@D $ArrayType$$$BY0BAA@D;
    initblk(ref $ArrayType$$$BY0BAA@D, 0, 256);
    <Module>.printf(ref <Module>.??_C@_0BJ@MNCFGMHN@Please?5input?5your?5flag?3?5?$AA@, __arglist());
    <Module>.scanf(ref <Module>.??_C@_05HPMPOKFN@?$CF?$FL?$FO?6?$FN?$AA@, __arglist((sbyte*)(&$ArrayType$$$BY0BAA@D)));
    sbyte* ptr = ref $ArrayType$$$BY0BAA@D;
    if ($ArrayType$$$BY0BAA@D != null)
    {
        do
        {
            ptr += 1L;
        }
        while (*ptr != 0);
    }
    if (ptr - (ref $ArrayType$$$BY0BAA@D) != 70U)
    {
        <Module>.printf(ref <Module>.??_C@_0M@IIPHMAMA@Try?5again?$CB?6?$AA@, __arglist());
        return -1;
    }
    // 102 108 97 103 123 125
    // flag{}
    if ($ArrayType$$$BY0BAA@D == 102 && *((ref $ArrayType$$$BY0BAA@D) + 1) == 108 && *((ref $ArrayType$$$BY0BAA@D) + 2) == 97 && *((ref $ArrayType$$$BY0BAA@D) + 3) == 103 && *((ref $ArrayType$$$BY0BAA@D) + 4) == 123 && *((ref $ArrayType$$$BY0BAA@D) + 69) == 125)
    {
        $ArrayType$$$BY0EA@E $ArrayType$$$BY0EA@E;
        cpblk(ref $ArrayType$$$BY0EA@E, (ref $ArrayType$$$BY0BAA@D) + 5, 64);
        uint num = 0U;
        uint num2 = 0U;
        $ArrayType$$$BY188E* ptr2 = &<Module>.sudoku;
        do
        {
            uint num3 = 0U;
            $ArrayType$$$BY188E* ptr3 = ptr2;
            do
            {
                if (*(byte*)ptr3 == 15)
                {
                    byte b = *((ulong)num + (ref $ArrayType$$$BY0EA@E));
                    if (b < 48 || b > 57)  // 0 9
                    {
                        goto IL_109;
                    }
                    *(byte*)ptr3 = b - 48;
                    num += 1U;
                }
                num3 += 1U;
                ptr3 += 1L / (long)sizeof($ArrayType$$$BY188E);
            }
            while (num3 < 9U);
            num2 += 1U;
            ptr2 += 9L / (long)sizeof($ArrayType$$$BY188E);
        }
        while (num2 < 9U);
        uint num4 = 1U;
        uint num5 = 1U;
        uint num6 = 0U;
        long num7 = 0L;
        while (num4 == 1U)
        {
            long num8 = 0L;
            uint num9 = 1U;
            while (num4 == 1U)
            {
                uint num10 = num9;
                if (num9 < 9U)
                {
                    long num11 = (long)((ulong)num9);
                    byte b2 = *(num7 + num8 + (ref <Module>.sudoku));
                    num4 = 1U;
                    $ArrayType$$$BY188E* ptr4 = num7 + num11 + (ref <Module>.sudoku);
                    while (b2 != *(byte*)ptr4)
                    {
                        num10 += 1U;
                        ptr4 += 1L / (long)sizeof($ArrayType$$$BY188E);
                        if (num10 >= 9U)
                        {
                            goto IL_17F;
                        }
                    }
                    num4 = 0U;
                }
                IL_17F:
                num9 += 1U;
                num8 += 1L;
                if (num9 - 1U >= 9U)
                {
                    break;
                }
            }
            num6 += 1U;
            num7 += 9L;
            if (num6 >= 9U)
            {
                break;
            }
        }
        uint num12 = 0U;
        long num13 = 0L;
        while (num5 == 1U)
        {
            uint num14 = 1U;
            $ArrayType$$$BY188E* ptr5 = num13 + (ref <Module>.sudoku);
            while (num5 == 1U)
            {
                uint num15 = num14;
                if (num14 < 9U)
                {
                    $ArrayType$$$BY188E* ptr6 = num14;
                    byte b3 = *(byte*)ptr5;
                    num5 = 1U;
                    $ArrayType$$$BY188E* ptr7 = ptr6 * 9L + num13 / (long)sizeof($ArrayType$$$BY188E) + (ref <Module>.sudoku) / sizeof($ArrayType$$$BY188E);
                    while (b3 != *(byte*)ptr7)
                    {
                        num15 += 1U;
                        ptr7 += 9L / (long)sizeof($ArrayType$$$BY188E);
                        if (num15 >= 9U)
                        {
                            goto IL_209;
                        }
                    }
                    num5 = 0U;
                }
                IL_209:
                num14 += 1U;
                ptr5 += 9L / (long)sizeof($ArrayType$$$BY188E);
                if (num14 - 1U >= 9U)
                {
                    break;
                }
            }
            num12 += 1U;
            num13 += 1L;
            if (num12 >= 9U)
            {
                break;
            }
        }
        if (num4 == 1U && num5 == 1U)
        {
            $ArrayType$$$BY133E $ArrayType$$$BY133E = 33;  // !
            *((ref $ArrayType$$$BY133E) + 1) = 45;  // -
            *((ref $ArrayType$$$BY133E) + 2) = 63;  // ?
            *((ref $ArrayType$$$BY133E) + 3) = 43;  // +
            *((ref $ArrayType$$$BY133E) + 4) = 43;
            *((ref $ArrayType$$$BY133E) + 5) = 43;
            *((ref $ArrayType$$$BY133E) + 6) = 45;
            *((ref $ArrayType$$$BY133E) + 7) = 43;
            *((ref $ArrayType$$$BY133E) + 8) = 45;
            *((ref $ArrayType$$$BY133E) + 9) = 43;
            *((ref $ArrayType$$$BY133E) + 10) = 43;
            *((ref $ArrayType$$$BY133E) + 11) = 43;
            *((ref $ArrayType$$$BY133E) + 12) = 43;
            *((ref $ArrayType$$$BY133E) + 13) = 45;
            *((ref $ArrayType$$$BY133E) + 14) = 45;
            *((ref $ArrayType$$$BY133E) + 15) = 43;
            byte b4 = 0;
            byte b5 = 0;
            uint num16 = 0U;
            do
            {
                int num17 = (int)(*((ulong)num + (ref $ArrayType$$$BY0EA@E)));
                num += 1U;
                if (num17 != 65)  // A
                {
                    if (num17 != 68)  // D
                    {
                        if (num17 != 83)  // S
                        {
                            if (num17 == 87)  // W
                            {
                                if (b4 == 0)
                                {
                                    goto IL_323;
                                }
                                b4 -= 1;
                            }
                        }
                        else
                        {
                            if (b4 == 3)
                            {
                                goto IL_330;
                            }
                            b4 += 1;
                        }
                    }
                    else
                    {
                        if (b5 == 3)
                        {
                            goto IL_33D;
                        }
                        b5 += 1;
                    }
                }
                else
                {
                    if (b5 == 0)
                    {
                        goto IL_34A;
                    }
                    b5 -= 1;
                }
                if (*((ulong)b5 + (ref $ArrayType$$$BY133E) + (ulong)b4 * 4UL) == 45)  // -
                {
                    goto IL_357;
                }
                num16 += 1U;
            }
            while (num16 < 8U);
            if (*((ulong)b5 + (ref $ArrayType$$$BY133E) + (ulong)b4 * 4UL) == 63)  // ?
            {
                <Module>.printf(ref <Module>.??_C@_0BB@MGPKLNCH@You?5are?5winner?$CB?6?$AA@, __arglist());
                return 0;
            }
            goto IL_381;
            IL_323:
            <Module>.printf(ref <Module>.??_C@_0M@IIPHMAMA@Try?5again?$CB?6?$AA@, __arglist());
            return -1;
            IL_330:
            <Module>.printf(ref <Module>.??_C@_0M@IIPHMAMA@Try?5again?$CB?6?$AA@, __arglist());
            return -1;
            IL_33D:
            <Module>.printf(ref <Module>.??_C@_0M@IIPHMAMA@Try?5again?$CB?6?$AA@, __arglist());
            return -1;
            IL_34A:
            <Module>.printf(ref <Module>.??_C@_0M@IIPHMAMA@Try?5again?$CB?6?$AA@, __arglist());
            return -1;
            IL_357:
            <Module>.printf(ref <Module>.??_C@_0M@IIPHMAMA@Try?5again?$CB?6?$AA@, __arglist());
            return -1;
        }
        goto IL_381;
        IL_109:
        <Module>.printf(ref <Module>.??_C@_0M@IIPHMAMA@Try?5again?$CB?6?$AA@, __arglist());
        return -1;
    }
    IL_381:
    <Module>.printf(ref <Module>.??_C@_0M@IIPHMAMA@Try?5again?$CB?6?$AA@, __arglist());
    return -1;
}

开头规定了格式：flag{<64个字符>}
没找到 &<Module>.sudoku 初始化的位置，调试可以得到初始值为：

1	`[15,15,2,15,15,7,15,15,15,15,6,15,9,15,15,4,15,15,15,9,15,2,5,15,15,15,3,15,15,15,4,15,15,1,15,15,7,3,15,15,6,15,15,15,15,15,15,9,5,3,15,15,6,15,15,15,6,3,4,15,15,7,15,8,15,15,15,15,15,15,15,9,15,15,15,15,15,15,15,5,15]`