N1Junior-Writeup

总结

好的挑战，英雄联盟，爱来自中国！

刚好是碰到了最近在学的几个点，unicon，代码混淆等等，算是一个实践的过程，而且相较于前几场比赛几乎都在搞加密算法，平时rust和go也做的少，所以N1junior的体验还是挺好的，可惜现在已经是大二老油条咯😭

junior_enc

pyc字节码分析 + unicon + AESmagic

HACKING

一看是pyc当然想反编译，不过我一开始做的是checkin-rs，后面降难度了直接看源码咯~

要分析的主要是这几大块

Unicon

程序加载了shellcode到ARM架构上，具体如下，那么要看他干了啥的话，

mu = Uc(UC_ARCH_ARM, UC_MODE_THUMB)

dump出shellcode后直接用IDA加载就能看了漂亮的伪代码啦😋

int __fastcall sub_0(int result)
{
  _BYTE *v1; // [sp+4h] [bp-20h]
  char v2; // [sp+Fh] [bp-15h]
  int m; // [sp+10h] [bp-14h]
  int k; // [sp+14h] [bp-10h]
  int j; // [sp+18h] [bp-Ch]
  int i; // [sp+1Ch] [bp-8h]

  v1 = (_BYTE *)result;
  for ( i = 0; i <= 31; ++i )
  {
    result = (unsigned __int8)(v1[i] & ~v1[(i + 1) % 32]);
    v1[i] = v1[i] & ~v1[(i + 1) % 32] | ~v1[i] & v1[(i + 1) % 32];
  }
  for ( j = 0; j <= 31; ++j )
  {
    if ( (j & 1) != 0 )
      v1[j] += 6;
    else
      v1[j] += 9;
  }
  for ( k = 0; k <= 31; k += 2 )
  {
    v2 = v1[k];
    v1[k] = v1[k + 1];
    v1[k + 1] = v2;
  }
  for ( m = 1; m <= 31; ++m )
  {
    result = (unsigned __int8)v1[m];
    v1[m] = (v1[m] | v1[m - 1]) & ~(result & v1[m - 1]);
  }
  return result;
}

这里的加密逻辑也是挺简单的，根据for循环分成四段：

1. result不用管，再者是一个MBA混淆，实际上是异或input[i] ^= input[(i + 1) % 32]
2. 2个data为一组进行add（有脏东西，等会说－O－）
3. 对换
4. 也是MBA混淆，实际上是异或

hookcode

上面留了个伏笔，就是hook_code函数改写了add的数据，下面才是part2真正的加密逻辑

for ( j = 0; j <= 31; ++j )
  {
    if ( (j & 1) != 0 )
      input[j] += 8;                            // 奇数
    else
      input[j] += 18;                           // 偶数
  }

AES魔改

这里的AES也有脏东西☹搞了贼久才发现

SubBytes层换成了SubBytes_INV

行移位层从 0 <<<1 <<<2 <<<3， 改成：>>>1 >>>2 >>>3 >>>4

赛博厨子aes16位时怪怪的，输出是32位的？？？

EXP

from numpy import zeros  # 矩阵的初始化
from copy import deepcopy  # 对于多级列表得采取深度复制避免对中间态矩阵的影响
from functools import reduce  # 对于可迭代对象的累点积（自定义点积）的函数
from binascii import unhexlify

class AES128():
    def __init__(self, key):

        self.key = key  # 密钥（固定为16个字符）

        self.Key2Matrix()  # 密钥转密钥矩阵

        self.Key_extension()  # 密钥扩展

    def Text2Matrix(self):  # 文本转文本矩阵
        # 初始化文本矩阵（ECB模式，所以矩阵各元素初始化为0）
        self.Text_Matrix = zeros((4, 4), dtype=int)

        for x in range(len(self.text)):  # 遍历将文本元素转换为ASCILL码并赋值给矩阵
            self.Text_Matrix[x % 4][x//4] = ord(self.text[x])
        pass

    def Key2Matrix(self):  # 密钥转密钥矩阵
        self.Key_Matrix = zeros((4, 44), dtype=int)  # 初始化密钥矩阵

        for x in range(len(self.key)):  # 遍历将密钥元素转换为ASCILL码并赋值给矩阵
            self.Key_Matrix[x % 4][x // 4] = ord(self.key[x])

    def DeText2Matrix(self):  # 密文本转密文本矩阵
        # 初始化密文本矩阵（ECB模式，所以矩阵各元素初始化为0）
        self.DeText_Matrix = zeros((4, 4), dtype=int)

        for x in range(len(self.detext)//2):  # 遍历将密文本元素转换为整数并赋值给矩阵
            self.DeText_Matrix[x % 4][x //
                                      4] = int(self.detext[2*x], 16)*16+int(self.detext[2*x+1], 16)

    def Key_extension(self):  # 密钥扩展
        self.sbox = [0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
                     0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
                     0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
                     0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
                     0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
                     0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
                     0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
                     0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
                     0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
                     0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
                     0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
                     0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
                     0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
                     0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
                     0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
                     0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16, ]
        
        self.invsbox = [0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB,
                     0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,
                     0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E,
                     0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25,
                     0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92,
                     0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84,
                     0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06,
                     0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B,
                     0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73,
                     0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E,
                     0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B,
                     0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4,
                     0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F,
                     0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF,
                     0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61,
                     0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, 0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D]
        
        self.Rconj = [[0x01, 0x00, 0x00, 0x00], [0x02, 0x00, 0x00, 0x00], [0x04, 0x00, 0x00, 0x00], [0x08, 0x00, 0x00, 0x00], [0x10, 0x00, 0x00, 0x00],
                      [0x20, 0x00, 0x00, 0x00], [0x40, 0x00, 0x00, 0x00], [0x80, 0x00, 0x00, 0x00], [0x1B, 0x00, 0x00, 0x00], [0x36, 0x00, 0x00, 0x00]]
        for i in range(4, 44):
            if i % 4:
                # W[i]=W[i-4]⨁W[i-1]
                self.Key_Matrix[:, i] = self.XOR(
                    self.Key_Matrix[:, i - 4], self.Key_Matrix[:, i - 1])

            else:

                # 求T（b）

                # 1.字循环
                temp = self.Byte_Cycle(self.Key_Matrix[:, i - 1], 1, 1)

                # 2.字节代换
                temp = self.Byte_Substitution(temp, 1)

                # 3.轮常量异或

                temp = self.XOR(temp, self.Rconj[i // 4 - 1])

                # W[i]=W[i-4]⨁T(W[i-1])
                self.Key_Matrix[:, i] = self.XOR(
                    self.Key_Matrix[:, i - 4], temp)  # 密钥扩展已完成

    def encrypto(self, text):

        self.text = text  # 文本（最长为16个字符）

        self.Text2Matrix()  # 文本转文本矩阵

        self.Column_mixed_fixed_matrix = [[0x02, 0x03, 0x01, 0x01],
                                          [0x01, 0x02, 0x03, 0x01],
                                          [0x01, 0x01, 0x02, 0x03],
                                          [0x03, 0x01, 0x01, 0x02]]

        self.Intermediate_Matrix = self.Text_Matrix  # 保留原始文本矩阵

        self.AES_encrypto1_9()  # 前九轮单调循环

        self.AES_encrypto10()  # 第十轮与前九轮有区别

        return self.final_encryptohex()

    def decrypto(self, detext):

        self.detext = detext  # 密文本（最长为16个字符）

        self.DeText2Matrix()  # 密文本转密文本矩阵

        self.invsbox = [0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB,
                        0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,
                        0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E,
                        0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25,
                        0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92,
                        0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84,
                        0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06,
                        0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B,
                        0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73,
                        0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E,
                        0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B,
                        0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4,
                        0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F,
                        0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF,
                        0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61,
                        0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, 0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D]

        self.Inverse_column_mixed_fixed_matrix = [[0x0e, 0x0b, 0x0d, 0x09],
                                                  [0x09, 0x0e, 0x0b, 0x0d],
                                                  [0x0d, 0x09, 0x0e, 0x0b],
                                                  [0x0b, 0x0d, 0x09, 0x0e]]

        self.Intermediate_Matrix = self.DeText_Matrix  # 保留原始密文本矩阵

        self.AES_decrypto1_9()  # 前九轮单调循环

        self.AES_decrypto10()  # 第十轮与前九轮有区别

        return self.final_decryptostr()

    def AES_encrypto1_9(self):
        # 首次特殊轮密钥加
        self.Round_key_addition(0)

        for i in range(9):
            pass
            # 字节代换
            for j in range(4):
                self.Intermediate_Matrix[:, j] = self.Byte_Substitution(
                    self.Intermediate_Matrix[:, j], 0) #magic

            # 行移位
            pass
            # print(f"\n{self.Intermediate_Matrix}")
            for k in range(4):
                self.Intermediate_Matrix[k, :] = self.Byte_Cycle(
                    self.Intermediate_Matrix[k, :], 0, k+1) #magic

            # 列混合
            pass
            self.Column_mixing(1)

            # 轮密钥加
            pass
            self.Round_key_addition(i+1)
            pass

    def AES_encrypto10(self):

        # 字节代换

        for j in range(4):
            self.Intermediate_Matrix[:, j] = self.Byte_Substitution(
                self.Intermediate_Matrix[:, j], 0)
        pass

        # 行移位
        for k in range(4):
            self.Intermediate_Matrix[k, :] = self.Byte_Cycle(
                self.Intermediate_Matrix[k, :], 0, k+1)

        # 轮密钥加
        self.Round_key_addition(10)

    def AES_decrypto1_9(self):

        # 首次特殊轮密钥加
        self.Round_key_addition(10)

        for i in range(9):

            # 行移位
            for k in range(4):
                self.Intermediate_Matrix[k, :] = self.Byte_Cycle(
                    self.Intermediate_Matrix[k, :], 1, k+1) #magic

            # 字节代换
            for j in range(4):
                self.Intermediate_Matrix[:, j] = self.Byte_Substitution(
                    self.Intermediate_Matrix[:, j], 1) #magic

            # 轮密钥加
            self.Round_key_addition(10 - i - 1)

            # 列混合
            self.Column_mixing(0)

    def AES_decrypto10(self):

        # 行移位
        for k in range(4):
            self.Intermediate_Matrix[k, :] = self.Byte_Cycle(
                self.Intermediate_Matrix[k, :], 1, k+1) #magic

        # 字节代换
        for j in range(4):
            self.Intermediate_Matrix[:, j] = self.Byte_Substitution(
                self.Intermediate_Matrix[:, j], 1) #magic

        # 轮密钥加
        self.Round_key_addition(0)

    def Round_key_addition(self, rounds):  # 轮密钥加

        temp = deepcopy(self.Intermediate_Matrix)  # 对于多级列表得采取深度复制避免对中间态矩阵的影响

        for i in range(4):
            self.Intermediate_Matrix[:, i] = self.XOR(
                temp[:, i], self.Key_Matrix[:, 4*rounds+i])

    def Byte_Substitution(self, Substitution_element, whichbox):  # 字节代换

        if whichbox == 1:
            return list(map(lambda x: self.sbox[Substitution_element[x]], range(4)))

        else:
            return list(map(lambda x: self.invsbox[Substitution_element[x]], range(4)))

    def Byte_Cycle(self, cycle_element, direction, t=0):  # 字循环/行位移
        if direction:
            return list(map(lambda i: cycle_element[(i + t) % 4], range(4)))

        else:
            return list(map(lambda i: cycle_element[(i - t) % 4], range(4)))

    def Column_mixing(self, inverse):  # 列混合

        temp = deepcopy(self.Intermediate_Matrix)  # 对于多级列表得采取深度复制避免对中间态矩阵的影响

        if inverse:
            for i in range(4):
                for j in range(4):
                    self.Intermediate_Matrix[i][j] = self.Ques_element(
                        temp[:, j], self.Column_mixed_fixed_matrix[i])
        else:
            for i in range(4):
                for j in range(4):
                    self.Intermediate_Matrix[i][j] = self.Ques_element(
                        temp[:, j], self.Inverse_column_mixed_fixed_matrix[i])

    def XOR(self, elementx, elementy):  # 异或

        return list(map(lambda i: elementx[i] ^ elementy[i], range(4)))

    def Xtime(self, x):  # xtime为域上乘法提供基础

        if x // 128:
            return ((x * 2) ^ (0x1b)) % 256
        else:
            return (x * 2) % 256

    def Multiplication_over_field(self, x, y):  # 域上乘法

        Xtime_weight = [x]  # 对于x的权的列表并初始化

        result = 0
        for i in range(8):
            Xtime_weight.append(self.Xtime(Xtime_weight[i]))

        for j in range(8):
            if bin(y)[2:].rjust(8, '0')[j] == '1':
                result = result ^ Xtime_weight[7 - j]
        return result

    def Ques_element(self, element0, element1):  # 自定义求下标为（x,y）的单个矩阵元素

        temp = list(
            map(lambda x, y: self.Multiplication_over_field(x, y), element0, element1))
        return reduce(lambda x, y: x ^ y, temp)

    def hex_print_matrix(self, element, rounds=0):  # 以十六进制打印矩阵

        for i in range(4):
            for j in range(4):
                print("%x" % (element[i][j]), end="  ")
            print()

    def final_encryptohex(self):
        result = []

        for i in range(4):

            result.append("".join(
                list(map(lambda x: hex(x)[2:].rjust(2, '0'), self.Intermediate_Matrix[:, i]))))
        result = "".join(result)
        return result

    def final_decryptostr(self):
        temp = []

        for i in range(4):

            temp.append("".join(
                list(map(lambda x: hex(x)[2:].rjust(2, '0'), self.Intermediate_Matrix[:, i]))))
        temp = "".join(temp)

        result = unhexlify(temp.encode('utf-8'))
        return result

def Evidence(text, key):
    # 要求key长度为16
    aes = AES128(key)
    enc = aes.encrypto(text)
    print(enc.encode('utf-8'))
    detext = aes.decrypto(enc)
    print(detext)

def unicon_dec(enc):
    print(enc)
    for i in range(len(enc)-1,0,-1):
        enc[i] ^= enc[i-1]
    
    print(enc)
    for i in range(0,len(enc),2):
        tmp = enc[i]
        enc[i] = enc[i+1]
        enc[i+1] = tmp
        
    print(enc)
    for i in range(0,len(enc),2):
        enc[i]= (enc[i]- 18)&0xFF
        enc[i+1]= (enc[i+1]-8)&0xFF
    
    print(enc)
    for i in range(len(enc)-1,-1,-1):
        enc[i] ^= enc[(i+1)%32]
    
    return enc

key = "anptntmxyuokmlwv"
model = AES128(key)
print(model.encrypto("1234567812345678")) # test
Evidence("1234567812345678",key)

cipher = [61, 182, 175, 175, 2, 168, 124, 177, 32, 240, 230, 220, 58, 123, 165, 238, 53, 192, 237, 21, 175, 91, 224, 150, 133, 153, 54, 203, 79, 33, 193, 172]
cipher = bytes(cipher)
cipher = hex(int.from_bytes(cipher, 'big'))[2:]
c1 = cipher[:32]
c2 = cipher[32:]
output = model.decrypto(c1) + model.decrypto(c2)
print(unicon_dec(list(output)))

checkin-rs

HACKING1

一上来就是rust，rust就rust吧

对rust感觉还是啃汇编代码比较好，可能是还不够熟练吧，希望有大佬指导一下还有没有更好的方法 ( T_T )

对api大体分析可以发现这些是跟rust并发编程相关的内容，了解一下，这里作简要介绍

• std::thread::spawn 创建线程
• std::thread::JoinHandle::join 可以让主线程等待子线程执行完毕然后再继续执行
• std::sync::mpsc::Receiver::recv 接收通道信息，在这里用于接收flag的判断信息

了解到这里基本就有个思路就是input通过多线程的handler处理并判断，最后从通道输出判断信息

问题是handler在哪？

HACKING2

细心发现从网上搜到的示例代码，receiver必有sender，所以找，也是很幸运的找到了交叉引用

找到一个backtrace，里面的操作也是看着可疑，下断点验证一下，是不是input经过这个地方，是找对地方了

前面一大堆我是慢慢分析的qwq，所以非常非常慢，其实更好的方法还是对加密操作分段，再下断点观察，不过不知道为啥在这里我下不了硬件断点，值改变了也跟踪不了，小烦。。。

最后加密逻辑很简单，就是逆序再异或i

这里有个小技巧就是测试flag的时候尽量不重复，如123456789abcdefABCDEFGHIJKLMNOPQRSTUVWXYZghi 这样很容易发现规律

EXP

enc = [0x7D, 0x20, 0x23, 0x22, 0x25, 0x24, 0x68, 0x72, 0x6E, 0x56, 0x79, 0x62, 0x53, 0x79, 0x7D, 0x7A, 0x62, 0x4E, 0x7C, 0x7A, 0x7F, 0x76, 0x73, 0x7F, 0x7B, 0x46, 0x7F, 0x68, 0x6E, 0x78, 0x68, 0x7A, 0x52, 0x7E, 0x5B, 0x50, 0x45, 0x40, 0x5D, 0x4C, 0x46, 0x5C, 0x5A, 0x48, 0x49,0x5E]
for i in range(len(enc)):
    enc[i]^=i
enc = enc[::-1]
print(bytes(enc))

n0th1ngG0

HACKING

阿这。。。不知道为啥linux版本的动调不起来

换成exe的就直接能开了，那就拿exe分析好了

降了难度后动调起来GO也不是特别难看，很容易能发现check的地方

然后找到加密操作的位置，很明显就是这里

进去一看有两个WTF，顺带说说还有些小坑…没动调前还以为这是同一个函数

上一个函数不是关键，给input挂上断点就能发现关键操作是在第二个WTF

加密逻辑挺简单的，前面都是rax的变化不需要逆，然后猜一手MBA，拿到xorkey后就可以getflag咯~

EXP

enc = [0x51, 0x23, 0x48, 0x73, 0x13, 0x50, 0x2C, 0x63, 0x61, 0xBA, 0x60, 0x2E, 0x54, 0x65, 0x29, 0x66, 0x81, 0xAB, 0x87, 0x34, 0x1A, 0xD0, 0x71, 0xAE, 0xA7, 0xE8, 0xAC, 0xCC, 0xEC, 0x75, 0x56, 0xFB, 0x79]
tmp = [0x51, 0x23, 0x48, 0x73, 0x13, 0x50, 0x2C, 0x63, 0x61, 0xBA, 0x60, 0x2E, 0x54, 0x65, 0x29, 0x66, 0x81, 0xAB, 0x87, 0x34, 0x1A, 0xD0, 0x71, 0xAE, 0xA7, 0xE8, 0xAC, 0xCC, 0xEC, 0x75, 0x56, 0xFB]
test = "1234567891234567891234567891234567"
enc_test = [0x13, 0x74, 0x18, 0x37, 0x53, 0x08, 0x70, 0x20, 0x16, 0xBA, 0x0D, 0x57, 0x35, 0x3E, 0x2E, 0x61, 0xCB, 0xCD, 0x84, 0x36, 0x1B, 0xD7, 0x1B, 0xA9, 0xE3, 0x8F, 0xA1, 0x8A, 0xED, 0x35, 0x52, 0xA3, 0x7C]
key = []
for i in range(len(enc_test)):
    key.append(enc_test[i]^ord(test[i]))
    enc[i] ^= key[i]

print(bytes(enc))