RE

BUU_RE_Youngter-drive

查壳,upx

 

 

 

 脱壳,32位,查字符

 

 

 

 

 

主函数:

int __cdecl main_0(int argc, const char **argv, const char **envp)
{
  HANDLE v4; // [esp+D0h] [ebp-14h]
  HANDLE hObject; // [esp+DCh] [ebp-8h]

  ((void (*)(void))sub_4110FF)();
  ::hObject = CreateMutexW(0, 0, 0);
  j_strcpy(Destination, Source);
  hObject = CreateThread(0, 0, StartAddress, 0, 0, 0);
  v4 = CreateThread(0, 0, sub_41119F, 0, 0, 0);
  CloseHandle(hObject);
  CloseHandle(v4);
  while ( dword_418008 != -1 )
    ;
  sub_411190();
  CloseHandle(::hObject);
  return 0;
}

 

 

[SWPUCTF 2021 新生赛]fakebase

flag = 'xxxxxxxxxxxxxxxxxxx'

s_box = 'qwertyuiopasdfghjkzxcvb123456#$'
tmp = ''
for i in flag:
    tmp += str(bin(ord(i)))[2:].zfill(8)
b1 = int(tmp,2)
s = ''
while b1//31 != 0:
    s += s_box[b1%31]
    b1 = b1//31

print(s)

# s = u#k4ggia61egegzjuqz12jhfspfkay

大致加密流程就是把flag挨个取出然后拼接成一个字符串,然后再从s_box中取对应的值

也可以简单理解成base31

s='u#k4ggia61egegzjuqz12jhfspfkay'
s_box = 'qwertyuiopasdfghjkzxcvb123456#$'
for j in range(31):
    num = j
    for i in s[::-1]:
        num = num * 31 + s_box.index(i)
    num = str(bin(num)[2:])
    num = num.zfill((len(num) // 8 + 1) * 8) 
    flag = ""
    for i in range(0,len(num),8):
        flag += chr(int(num[i:i+8],2))
    print (flag)

flag

NSSCTF{WHAt_BASe31}

标签：box,num,31,hObject,7.3,flag,7.1,b1
来源： https://www.cnblogs.com/1ucky/p/16434958.html