Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a friend who accidentally locked his computer's HDD, either by using password lock or some other way (he does not know).

The BIOS too was locked but I have dealt with that. Now I am supposed to work to unlock the HDD. I am using Hiren's Boot CD to unlock it. I am able to go to Unlock and it says "done" with a 0000 code for both user password or master password.

The problem is hat I am not able to issue dispwd command as it says again that the HDD has to be unlocked first to issue this command.

What did I miss or am I just faked by MHDD program? Is the HDD frozen? If so how can I unfreeze it?

share|improve this question
hdd is Hitachi SATA – tough Dec 23 '12 at 20:18
up vote 1 down vote accepted

I believe that the BIOS can (and many do) issue a "SECURITY FREEZE" command during initialization to drives that tell it not to accept further security commands.

Is this a SATA drive? Carefully attempt to connect the drive AFTER the BIOS boots up, and then see if MHDD can work on it. I think your chipset would have to support SATA hotplugging but since SATA physically supports hot swapping drives you aren't going to damage anything if you are careful (you CAN damage IDE drives doing this, though)

If that doesn't work, I'm reading here that it is suggested for issuing various security commands to drives using Linux hdparm that sleeping, then waking the machine does this too. Don't know if there is a way to resume MHDD (isn't it DOS based?) but you can issue unlock commands using hdparm. This may be an alternate way to do what you are trying to do.

Read the hdparm man page first, and notice there's a lot of warnings. Heed all of them, and I would suggest experimenting with that command from a live CD with no other drives connected other than the one you are trying to unlock.

share|improve this answer
I believe that the BIOS can (and many do) issue a "SECURITY FREEZE" command during initialization to drives that tell it not to accept further security commands. Yup; if you enter the wrong password three times (for either the BIOS or the HDD), it will request a special unlock password which you should be able to get from the manufacturer. An easier way however is to simply turn the system off. Then when you turn it back on, it should accept the normal password (up to three times, then lock you out again…) It’s not meant to be “secure”, just inconvenient enough to prevent general hacking. – Synetech Dec 23 '12 at 21:09
@ultrasawblade Thanks, yes the drive is SATA (HITACHI). Inserting the HDD after the BIOS boots up (after CD contents starts loading into the RAM/CD menu appearing in the screen) leaves PC turned off. However 2/3 incorrect password attempts for HDD leads to a continue menu and to boot select menu where I can choose which device to boot from. Looking at this sequence of events, I think that it has issued this secutiry freeze to the HDD. I have not tried hdparm I will give it a try. – tough Dec 23 '12 at 21:22

Depending on the computer's manufacturer, you may be able to more easily unlock the HDD by reverse engineering the hash shown when you try incorrect passwords too many times. (Some computers may require you press F12 before trying in order to show you that hash.)

For more information, see this article. (Note: Although the article is about BIOS unlocks, HDD unlocks should work the same way. I did it on an Acer Aspire.)

share|improve this answer
Please read the question again carefully. Your answer does not answer the original question. The link you reference is about unlocking the BIOS. The OP has already managed to do this as stated in his question "The BIOS too was locked but I have dealt with that.". He wants to unlock the hard disk. – DavidPostill Jun 17 '15 at 20:21
@DavidPostill The HDD lock is managed by the BIOS; Its the same system, and it works both for the BIOS itself and for the HDD. – Menasheh Jun 25 '15 at 16:49
Yes, but the password is stored on the hard disk itself. The hash is shown for the BIOS password not the HD password. Read Hard Disk Passwords Explained: Should You Set One to Secure Your Files? – DavidPostill Jun 25 '15 at 16:55
@DavidPostill That article doesn't say anything about hash-based password recovery. It does mention that HDD passwords can be bypassed with basic programs, and it recommends encryption instead. tough did not use encryption. Funny, the example bios screenshot that link shows me is the exact BIOS in which I got a hash which I used to reset an HDD just two weeks ago. – Menasheh Jun 25 '15 at 18:11

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.