Mounting a Hibernated Drive

When you hibernate a system under Windows XP, the current running state, which includes information about running processes, open files, etc., is stored in a file in the root directory of the system drive, i.e. C:\ named hiberfil.sys. The hiberfil.sys file is large enough to hold the uncompressed contents of the system's memory. You can determine how large that will be when the system is booted into Windows by running the command winver, which will display the physical memory available to Windows. For instance on a system where winver shows 490,800 KB available to Windows, the hiberfil.sys is 490,868 KB.

You can't examine the contents of the file while Windows is running, even from an administrator's account, because Windows maintains an open file handle for the file and will not allow it to be opened 1 .

You can examine the file by booting the system from a Linux LiveCD. A LiveCD2 allows you to boot a system from an operating system stored on a CD. Linux LiveCDs are available for many distributions of Linux.

I've used a Ubuntu LiveCD, which can be downloaded from Get Ubuntu to examine the hiberfil.sys file that was created on a Windows system.

After booting the system from the Linux LiveCD, you will need to mount the partition containing the hiberfil.sys file. On systems with a Serial ATA (SATA), the partition will likely be sda1. On systems with an Integrated Drive Electronics (IDE) drive, the partition will likely be designated as hda1. On Ubuntu, use sudo sh first to gain root access.

ubuntu@ubuntu:~$ sudo sh
# mkdir /mnt/hdd
# mount /dev/sda1 /mnt/hdd

If a system was placed in hibernation mode when shut down, the hiberfil.sys file will have hibr as the first four bytes in the file 3. There will be four bytes of zeroes immediately afterwards, i.e. the "nul" character. If there was an attempt to boot the system from hibernation, but the attempt failed, the first four bytes will be changed from hibr to wake. On subsequent attempts to boot the system, you would then see the information below.

The last attempt to restart the system from its previous location
failed. Attempt to restart again?

      Delete restoration data and proceed to sytem boot menu
      Continue with system restart

If you try to mount a partition containing the hiberfil.sys file after booting into Linux, you may see a message like the one below when you issue the mount command, if the first four bytes of the hiberfil.sys file are hibr.

# mount /dev/sda1 /mnt/hdd
Windows is hibernated, refused to mount.
Failed to mount '/dev/sda1/': Operation not permitted
The NTFS partition is hibernated.
Please resume and shutdown Windows
properly, so mounting could be done safely

The drive can still be mounted in read-only mode by using the command mount -r /dev/sda1 /mnt/hdd. You can then switch to read-write mode by using the command mount -o remount rw /mnt/hdd

When I attempted to mount a drive where the first four bytes of hiberfil.sys were wake, instead of hibr, I was able to mount it with mount /dev/sda1 /mnt/hdd. You can verify how the drive is mounted by looking at /etc/mtab. If you see rw, it is mounted with read and write access.

# cat /etc/mtab
proc /proc proc rw 0 0
sysfs /sys sysfs rw 0 0
tmpfs /lib/modules/2.6.22-14-generic/volatile tmpfs rw,mode=0755 0 0
tmpfs /lib/modules/2.6.22-14-generic/volatile tmpfs rw,mode=0755 0 0
varrun /var/run tmpfs rw,noexec,nosuid,nodev,mode=0755 0 0
varlock /var/lock tmpfs rw,noexec,nosuid,nodev,mode=1777 0 0
udev /dev tmpfs rw,mode=0755 0 0
devshm /dev/shm tmpfs rw 0 0
devpts /dev/pts devpts rw,gid=5,mode=620 0 0
tmpfs /tmp tmpfs rw,nosuid,nodev 0 0
/dev/sda1 /mnt/hdd fuseblk rw,nosuid,nodev,noatime,allow_other,blksize=4096 0 0

When the drive is mounted, you can view the contents of hiberfil.sys by using the od or hexdump commands.

# od -a /mnt/hdd/hiberfil.sys | more
# hexdump -C /mnt/hdd/hiberfil.sys | more

To view just the first 8 bytes of the file with od, you can use od -a -N 8.

# od -a -N 8 /mnt/hdd/hiberfil.sys
0000000   w   a   k   e nul nul nul nul

To edit the file, if you have the partition on which it resides mounted in read-write mode, you can use a binary editor, such as the GNOME Hexadecimal Editor (GHex), which you can get in Ubuntu by clicking on Applications and then selecting Add/Remove. GHex lets users view and edit a binary file in both hex and ascii with a multiple level undo/redo mechanism. When it is installed, it will be placed under Applications, Programming, Hex Editor, though I had a problem when I attempted to use it to edit a 1 GB hiberfil.sys file. When I attempted to open the file, GHex would close.


  1. Hiberfil.sys
    Forensics Wiki
  2. LiveCD
    Wikipedia, the free encyclopedia
  3. System Won't Resume from Hibernation
    MoonPoint Support