Is it safe to sell desktop after "factory reset"

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north2016
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Is it safe to sell desktop after "factory reset"

Post by north2016 »

I have a Dell desktop on which I did all my financial stuff that I would like to now sell. Is doing a "factory reset" adequate? Thanks
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anon_investor
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Re: Is it safe to sell desktop after "factory reset"

Post by anon_investor »

north2016 wrote: Tue Nov 23, 2021 5:33 pm I have a Dell desktop on which I did all my financial stuff that I would like to now sell. Is doing a "factory reset" adequate? Thanks
No, your data would still be retrievable from your hard drive with the right software.
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cheese_breath
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Re: Is it safe to sell desktop after "factory reset"

Post by cheese_breath »

anon_investor wrote: Tue Nov 23, 2021 5:37 pm
north2016 wrote: Tue Nov 23, 2021 5:33 pm I have a Dell desktop on which I did all my financial stuff that I would like to now sell. Is doing a "factory reset" adequate? Thanks
No, your data would still be retrievable from your hard drive with the right software.
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lthenderson
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Re: Is it safe to sell desktop after "factory reset"

Post by lthenderson »

I always remove and destroy the hard drive separately. If someone wants the old computer, they have to buy a new hard drive and install an operating system.
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cos
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Re: Is it safe to sell desktop after "factory reset"

Post by cos »

north2016 wrote: Tue Nov 23, 2021 5:33 pm I have a Dell desktop on which I did all my financial stuff that I would like to now sell. Is doing a "factory reset" adequate? Thanks
In most cases, you should be fine, but as anon_investor pointed out, in the rare case that you sell your computer to the wrong person, your data can be accessed with enough effort. If you really want to be safe, you can run shred on the entire hard drive. If you have an SSD, SED and TRIM are even better options.

Personally, I wouldn't sweat it too much.
Last edited by cos on Tue Nov 23, 2021 5:47 pm, edited 4 times in total.
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anon_investor
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Re: Is it safe to sell desktop after "factory reset"

Post by anon_investor »

OP you could buy a new hard drive and reinstall the OS on it and sell the computer without the old hard drive with your data.
dukeblue219
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Re: Is it safe to sell desktop after "factory reset"

Post by dukeblue219 »

If your reset tool wipes the hard drive even once you're fine.

Nobody other than the NSA is going to bother taking a random old desktop and spending the money necessary to forensically recover data at that level.

The internet provides all the personal data one could ever want to buy. Buying a computer on the off chance of recovering useful financial data is not practical.
DinkinFlicka
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Re: Is it safe to sell desktop after "factory reset"

Post by DinkinFlicka »

I haven’t done computer maintenance in a while, but several years ago DBAN was the go to method of clearing a hard drive. Not sure if it’s still the easiest way, but if you know how to make a bootable disk, it’s an option.

https://dban.org
02nz
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Re: Is it safe to sell desktop after "factory reset"

Post by 02nz »

When you reset Windows 10, there's an option which makes it more difficult to recover the data. I forget exactly what it's called, but it's adequate for most if you're not storing nuclear codes on your computer.
runner3081
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Re: Is it safe to sell desktop after "factory reset"

Post by runner3081 »

Nope, not safe. Dump hard drive.

Wouldn't believe the number of used computers I buy with tax returns, wills, banks statement and other items on there. Always funny.
02nz
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Re: Is it safe to sell desktop after "factory reset"

Post by 02nz »

runner3081 wrote: Tue Nov 23, 2021 6:20 pm Nope, not safe. Dump hard drive.

Wouldn't believe the number of used computers I buy with tax returns, wills, banks statement and other items on there. Always funny.
What does "dump hard drive" mean? And had those tax returns, will, etc, simply been left on the drive? Or had they been deleted, and you recovered others' personal data without authorization?
Last edited by 02nz on Tue Nov 23, 2021 6:48 pm, edited 1 time in total.
Yarlonkol12
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Re: Is it safe to sell desktop after "factory reset"

Post by Yarlonkol12 »

No, all your data would still be there and most likely easily retrievable using free software.

The safest option is to just remove the old hard drive and sell the computer without it, the new owner can use their own drive and software.

If you really wanted to sell the old hard drive with the computer. If the drive is mechanical, you should use a tool like DBAN which will perform a secure erase by writing random data over the entire disk. This takes a long time to run, several hours at least or much longer with larger drives. If the drive is SSD, you can't do this because the SSD wear leveling firmware prevents this type of software from working, but with the SSD you could use a tool like Veracrypt to encrypt the entire SSD, throw away the key, and then reformat the drive again
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UpperNwGuy
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Re: Is it safe to sell desktop after "factory reset"

Post by UpperNwGuy »

My sister is in the business, and she takes all of her old hard drives out into the backyard and busts them apart with an axe.

I'm not in that business, but I have never gotten rid of an old laptop or smartphone. I just keep them forever.
dukeblue219
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Re: Is it safe to sell desktop after "factory reset"

Post by dukeblue219 »

DinkinFlicka wrote: Tue Nov 23, 2021 5:47 pm I haven’t done computer maintenance in a while, but several years ago DBAN was the go to method of clearing a hard drive. Not sure if it’s still the easiest way, but if you know how to make a bootable disk, it’s an option.

https://dban.org
The problem with DBAN is that most computers use SSDs these days with their own block management and wear leveling algorithms. DBAN may end up inadvertently erasing and writing the same portions of the SSD thousands of times, wearing them out without actually doing anything for the rest of the drive.

On the other hand, an SSD wiped with the manufacturers tool is essentially unrecoverable to all but the most dedicated criminal with specialized hardware (and likely some luck). If it was encrypted as well, theres zero concern.

These ideas of shooting, smashing, or grinding hard drives are absurd and entirely based on fear mongering.
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anon_investor
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Re: Is it safe to sell desktop after "factory reset"

Post by anon_investor »

UpperNwGuy wrote: Tue Nov 23, 2021 6:50 pm My sister is in the business, and she takes all of her old hard drives out into the backyard and busts them apart with an axe.

I'm not in that business, but I have never gotten rid of an old laptop or smartphone. I just keep them forever.
Do I dare ask what is "the business"?
UpperNwGuy
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Re: Is it safe to sell desktop after "factory reset"

Post by UpperNwGuy »

anon_investor wrote: Tue Nov 23, 2021 6:59 pm
UpperNwGuy wrote: Tue Nov 23, 2021 6:50 pm My sister is in the business, and she takes all of her old hard drives out into the backyard and busts them apart with an axe.

I'm not in that business, but I have never gotten rid of an old laptop or smartphone. I just keep them forever.
Do I dare ask what is "the business"?
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1nv3s70r
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Re: Is it safe to sell desktop after "factory reset"

Post by 1nv3s70r »

Remove the hard drive and before disposing make a nice big hole in it with a drill (easier than taking an axe to it!).
talzara
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Re: Is it safe to sell desktop after "factory reset"

Post by talzara »

dukeblue219 wrote: Tue Nov 23, 2021 5:46 pm If your reset tool wipes the hard drive even once you're fine.
Dell's website suggests using the Windows 10 Reset this PC tool: https://www.dell.com/support/kbdoc/en-u ... mputer#PBR

Windows 10 Reset this PC does not wipe the hard drive even once. The data is still there on the hard drive.
02nz wrote: Tue Nov 23, 2021 6:12 pm When you reset Windows 10, there's an option which makes it more difficult to recover the data. I forget exactly what it's called, but it's adequate for most if you're not storing nuclear codes on your computer.
The option is "Remove everything." Your files will be deleted, so it will look like there is no data there. However, the actual data is still left behind on the hard drive.

It does not make it "more difficult to recover the data." It only makes it inconvenient because you don't know where anything is. It's like taking a filing cabinet and destroying the manila folders, but not shredding the financial statements inside the folders.
dukeblue219
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Re: Is it safe to sell desktop after "factory reset"

Post by dukeblue219 »

talzara wrote: Tue Nov 23, 2021 7:10 pm The option is "Remove everything." Your files will be deleted, so it will look like there is no data there. However, the actual data is still left behind on the hard drive.

It's like taking a filing cabinet and destroying the manila folders, but not shredding the financial statements inside the folders.
If it's a SSD, it's more like cutting each word off the page ransom-note style, then dumping all the words into the cabinet randomly.

There's a reason people just factory reset iPhones and nobody would ever think of desoldering the flash, smashing the ICs, and selling the empty phone casing. Even if the bits of data are still there, the controller won't let someone access low-level data like that. A very, very sophisticated forensic analyst can if the data is unencrypted.

For an HD, yes, wipe it once and move on.
runner3081
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Re: Is it safe to sell desktop after "factory reset"

Post by runner3081 »

02nz wrote: Tue Nov 23, 2021 6:45 pm
runner3081 wrote: Tue Nov 23, 2021 6:20 pm Nope, not safe. Dump hard drive.

Wouldn't believe the number of used computers I buy with tax returns, wills, banks statement and other items on there. Always funny.
What does "dump hard drive" mean? And had those tax returns, will, etc, simply been left on the drive? Or had they been deleted, and you recovered others' personal data without authorization?
Dump = remove and destroy.
anoop
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Re: Is it safe to sell desktop after "factory reset"

Post by anoop »

You can always use bleachbit. :)
https://www.bleachbit.org/
twh
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Re: Is it safe to sell desktop after "factory reset"

Post by twh »

dukeblue219 wrote: Tue Nov 23, 2021 7:16 pm
talzara wrote: Tue Nov 23, 2021 7:10 pm The option is "Remove everything." Your files will be deleted, so it will look like there is no data there. However, the actual data is still left behind on the hard drive.

It's like taking a filing cabinet and destroying the manila folders, but not shredding the financial statements inside the folders.
There's a reason people just factory reset iPhones
Factory resetting the iPhone deletes the key that is used to encrypt the memory. That is effectively a wipe.

Easy to find a tool to wipe a rotating disk hard drive.

Wiping an SSD should be done with a tool from the SSD manufacturer. There is a lot more going on with them, like spare memory areas that aren't exposed to normal software accessing the SSD.
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Re: Is it safe to sell desktop after "factory reset"

Post by AQ »

Not a technical person myself, but the following is one idea I came up:

Old data could be recovered because they must still sit somewhere even if one executed a 'delete' command. So one trick is to copy and paste some junky large files such as movies files to fill up the entire harddisk spaces. This way, any old data would have been completely overwritten, and thus nobody would be able to recover anything.

Does this idea make sense? If not what is wrong in my logic?
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Re: Is it safe to sell desktop after "factory reset"

Post by twh »

AQ wrote: Tue Nov 23, 2021 7:30 pm Not a technical person myself, but the following is one idea I came up:

Old data could be recovered because they must still sit somewhere even if one executed a 'delete' command. So one trick is to copy and paste some junky large files such as movies files to fill up the entire harddisk spaces. This way, any old data would have been completely overwritten, and thus nobody would be able to recover anything.

Does this idea make sense? If not what is wrong in my logic?
For rotating media disk drive, that does make sense and you understand it. But, don't do that, there is too much happening that may actually prevent what you think you are doing from actually happening. Just use a wipe tool. For SSD, it is more complicated, since many/most have spare areas they do not expose to the normal operating system. That is, there are areas you cannot write at all under normal circumstances.
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Re: Is it safe to sell desktop after "factory reset"

Post by talzara »

dukeblue219 wrote: Tue Nov 23, 2021 7:16 pm There's a reason people just factory reset iPhones
The OP has a Dell desktop PC, not an iPhone.
twh wrote: Tue Nov 23, 2021 7:27 pm Factory resetting the iPhone deletes the key that is used to encrypt the memory. That is effectively a wipe.

Easy to find a tool to wipe a rotating disk hard drive.

Wiping an SSD should be done with a tool from the SSD manufacturer. There is a lot more going on with them, like spare memory areas that aren't exposed to normal software accessing the SSD.
That's right. Wiping the drive is what makes it clean.

Windows 10 Reset this PC does not wipe the drive, and that is the problem.
02nz
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Re: Is it safe to sell desktop after "factory reset"

Post by 02nz »

talzara wrote: Tue Nov 23, 2021 7:10 pm
dukeblue219 wrote: Tue Nov 23, 2021 5:46 pm If your reset tool wipes the hard drive even once you're fine.
Dell's website suggests using the Windows 10 Reset this PC tool: https://www.dell.com/support/kbdoc/en-u ... mputer#PBR

Windows 10 Reset this PC does not wipe the hard drive even once. The data is still there on the hard drive.
02nz wrote: Tue Nov 23, 2021 6:12 pm When you reset Windows 10, there's an option which makes it more difficult to recover the data. I forget exactly what it's called, but it's adequate for most if you're not storing nuclear codes on your computer.
The option is "Remove everything." Your files will be deleted, so it will look like there is no data there. However, the actual data is still left behind on the hard drive.

It does not make it "more difficult to recover the data." It only makes it inconvenient because you don't know where anything is. It's like taking a filing cabinet and destroying the manila folders, but not shredding the financial statements inside the folders.
Beyond "Remove everything," there's an option to "clean the drive," which is what I was referring to. And that does perform a more thorough erase, where zeros are written to the drive (see https://www.techrepublic.com/article/re ... ng-option/). Again, not for computers that store the nuclear launch codes, but data thieves have far lower-hanging fruit than drives that have been erased this way.
talzara
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Re: Is it safe to sell desktop after "factory reset"

Post by talzara »

AQ wrote: Tue Nov 23, 2021 7:30 pm Old data could be recovered because they must still sit somewhere even if one executed a 'delete' command. So one trick is to copy and paste some junky large files such as movies files to fill up the entire harddisk spaces. This way, any old data would have been completely overwritten, and thus nobody would be able to recover anything.

Does this idea make sense? If not what is wrong in my logic?
It will get you 95% of the way there. Windows reserves a block of space for the hibernation file, and that will not get overwritten. It will not even get overwritten completely if you hibernate or shut down your PC!

That is why some of the IT people in this thread keep saying "wipe." That will overwrite 100% of the data. Whether it's a hard drive or an SSD, all the data will be gone for sure.
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whodidntante
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Re: Is it safe to sell desktop after "factory reset"

Post by whodidntante »

It's surprisingly difficult, at least if you are not a pro.

You can use the Windows "cipher" command to securely erase free space. However, due to overprovisioning, and a few other inconveniences that mean you can't touch every bit of data, even that can leave recoverable data. You want to use a secure erase command sent to the disk itself, and be quite sure it worked.

But my personal favorite is to harvest every valuable component then cremate every internal disk.
talzara
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Re: Is it safe to sell desktop after "factory reset"

Post by talzara »

02nz wrote: Tue Nov 23, 2021 7:49 pm Beyond "Remove everything," there's an option to "clean the drive," which is what I was referring to. And that does perform a more thorough erase, where zeros are written to the drive (see https://www.techrepublic.com/article/re ... ng-option/). Again, not for computers that store the nuclear launch codes, but data thieves have far lower-hanging fruit than drives that have been erased this way.
If it's a hard drive, then having Windows write zeroes to the drive will will get you 99% of the way there. It may be good enough for the OP.

If it's an SSD, this may not work. Some SSDs use internal compression. Writing all zeroes may not overwrite your data at all since it will compress down to almost nothing.
talzara
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Re: Is it safe to sell desktop after "factory reset"

Post by talzara »

twh wrote: Tue Nov 23, 2021 7:42 pm Just use a wipe tool. For SSD, it is more complicated, since many/most have spare areas they do not expose to the normal operating system. That is, there are areas you cannot write at all under normal circumstances.
With Shingled Magnetic Recording, even hard drives are starting to have inaccessible areas. Hard drives already had relocated sectors, but that was only a small amount of data. Now, it could be many megabytes.

It wouldn't be a bad idea to issue a secure erase command to an SMR hard drive in addition to using a wipe tool.
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Re: Is it safe to sell desktop after "factory reset"

Post by lazydavid »

It doesn't help OP, but for others to make this easier in the future, the best way to ensure complete data destruction with modern drives is to encrypt the drive BEFORE you start using it. That means that no sensitive data will EVER be stored on it in a manner that will be recoverable once the encryption key has been deleted.

Assuming you're using Bitlocker on a Windows machine, all you have to do prior to disposal is use Disk Management (from another machine or something like a WinPE boot drive) to delete the partition. This causes Windows to securely delete the encryption key, and now all data that has ever been stored on that drive is mathematically unrecoverable gibberish--even if it was spared out--and you can dispose of it safely.

For the past few years, I've been issuing Self-encrypting Drives (SEDs) to my users, which are managed with centralized software. If they're online, I can issue a secure erase from the management function, which does nothing more than generate a new encryption key and overwrite the existing one. if you're sitting at the machine, you can watch windows start to glitch for 15-30 seconds before it bluescreens (because it no longer has a system disk), and then never recovers. It's kind of fun to watch. :) Machines wiped in this manner meet all of our data destruction protocols.
London
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Re: Is it safe to sell desktop after "factory reset"

Post by London »

Anyone you sell/give the computer to will use CIA level tactics to access your old pictures and excel files as these are extremely valuable. Anyone you sell/give to will be a highly proficient operator, just waiting for your mundane data. Your life will now be a scene out of a movie.

Lol at these responses. Your data online is more valuable.
digit8
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Re: Is it safe to sell desktop after "factory reset"

Post by digit8 »

I mean….the odds are pretty good that you’d be fine with minimal effort….but run the cost benefit. How much can you get on a used computer these days, vs. the low, but nonzero chance of a data breach?
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Re: Is it safe to sell desktop after "factory reset"

Post by iamblessed »

Will installing linux (full format) over windows work for getting all the data wiped out?
twh
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Re: Is it safe to sell desktop after "factory reset"

Post by twh »

iamblessed wrote: Wed Nov 24, 2021 2:19 pm Will installing linux (full format) over windows work for getting all the data wiped out?
I'm not trying to be unkind. Why would you think that after all the posts from people who do know...do a wipe. Here's the thing about computers - what you don't know can hurt you. What is a "full format"? That can mean any number of things, most of which are not an entire erasure of the hard drive.
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