Shutdown the computer using assembly

Question

How can I shutdown the computer using only assembly code?

Answer 1

You can try using shellcode for x86Linux machine, this is not malicious code you know, just for fun. This shellcode only executes /sbin/poweroff only tested on Debian version 5.0.5.

#include 
#include 

char *shellcode = "\x31\xc0\x50\x68\x72\x6f\x66"
                  "\x66\x68\x70\x6f\x77\x65\x68"
                  "\x6e\x2f\x2f\x2f\x68\x2f\x73"
                  "\x62\x69\x89\xe3\x50\x53\x89"
                  "\xe1\xb0\x0b\xcd\x80\x31\xc0"
                  "\x50\x89\xe3\xb0\x01\xcd\x80";

int main(int argc, char *argv[]) {
    printf("shellcode length ->  %d bytes\n", (int)strlen(shellcode));
    int (*ret)()=(int(*)())shellcode;
    ret();

    return 0;
}

Or this shellcode executes shutdown -h now (run with root) :

#include 
#include 

char *shellcode =  "\x31\xc0\x31\xd2\x50\x66\x68\x2d"
                   "\x68\x89\xe7\x50\x6a\x6e\x66\xc7"
                   "\x44\x24\x01\x6f\x77\x89\xe7\x50"
                   "\x68\x64\x6f\x77\x6e\x68\x73\x68"
                   "\x75\x74\x68\x6e\x2f\x2f\x2f\x68"
                   "\x2f\x73\x62\x69\x89\xe3\x52\x56"
                   "\x57\x53\x89\xe1\xb0\x0b\xcd\x80";

int main(int argc, char *argv[]) {
    printf("shellcode length ->  %d bytes\n", (int)strlen(shellcode));
    int (*ret)()=(int(*)())shellcode;
    ret();

    return 0;
}