Delete external drive NTFS files from Mac or Linux

October 2, 2021 11:58 AM

How do I completely delete files on an external NTFS drive using my Mac or Linux computers - I have to return a computer under warranty but I have security concerns.

I have three computers: a tiny Linux laptop, an old Mac, and a spiffy new Windows box that recently died. But it's still under warranty, and I can return it for a replacement, so yay?

I've removed the C-drive from the dead Windows computer and installed it into an external ssd box so I can see it from my Mac or from by Linux laptop. I'm wondering if there's any way I can completely nuke the entire Firefox profile on this drive, because it has some saved Firefox logins for my IRA accounts. I know I could just change the passwords on these accounts, but I'm afraid there are other sensitive accounts/data that Firefox has saved that I'm not even remembering.

I should also note that I've never installed an email client on this computer, so anything with 2FA is safe. I've never logged into my bank accounts on this computer. But I'm not sure if Firefox knows my Amazon account, my library account, my domain registrar account, my METAFILTER ACCOUNT???

I know I'm being slightly paranoid about this, but any advice you can give would be appreciated.

posted by chocolatepeanutbuttercup to Computers & Internet (9 answers total)

You can't truly delete files unless you coincidentally overwrite the empty space. Ideally, you'd clear and overwrite the whole drive. Linux can do that with dd easily. I guess a Mac command line would be the same.

I'm not sure what you're expected to return for warranty, but obviously this action would also remove and overwrite Windows.
posted by Snijglau at 12:35 PM on October 2, 2021 [1 favorite]

I'd just use DD like mentioned above. Any legitimate service place would image the drive on a warranty return first thing anyways.
posted by Mitheral at 12:49 PM on October 2, 2021

If you were open to erasing the whole thing, Disk Utility will do the job on the Mac
posted by advicepig at 12:55 PM on October 2, 2021 [1 favorite]

Apple has a support doc on how to do this with Disk Utility. This has the option of overwriting the external drive with random data some number of times, if security is a concern, with the tradeoff of a longer erase time. The dd utility will not do this, by default, though you can re-run things manually on that platform.
posted by They sucked his brains out! at 1:23 PM on October 2, 2021

Response by poster: Thanks to all who answered - I will have to find out if it's acceptable to return it with an erased/overwritten hard drive. Otherwise, I guess I'm just going to have to change passwords and hope for the best. Thanks!
posted by chocolatepeanutbuttercup at 2:03 PM on October 2, 2021

it'd be surprising if warranty return didn't accept an erased hard drive, because presumably if they thought there was any chance of a software misconfiguration it'd be far quicker and easier for them to reimage the entire drive and restore it to some known state rather than try to figure out exactly what tangle each customer's filesystem had gotten into. some warranty returns might explicitly tell you to _not_ send in your drives.
posted by are-coral-made at 2:30 PM on October 2, 2021 [2 favorites]

From what I've read, because of the way SSDs manage data, utilities like shred won't work or will potentially damage an SSD.

You can use fuse and ntfs-3g to read/write to an NFTS drive from Linux. What I'd do if you want to be super-cautious, is install fuse and the ntfs-3g FUSE driver and then over-write the files several times with new data / garbage data. On a Windows machine see this Mozilla support doc, but it looks like it'd be C:\Users\[youruser]\AppData\Roaming\Mozilla\Firefox\Profiles or thereabouts.

You could nuke the directories under there or go spelunk under the randomly-named directory with your user data and over-write all key4.db and logins.json and such with junk data. (e.g. $ cat /dev/random > key4.db).
posted by jzb at 4:05 PM on October 2, 2021

GNU shred and ntfs-3g via fuse would erase the contents of Firefox's profile files, and replace them with random data or zeros. The SSD controller won't supply data from cells it has marked erased.

The ultra-paranoid strategy would be to shred (only one pass, -n 1) the files, clone the filesystem to another device, secure-erase the SSD using its controller, then rewrite the cloned image which then won't have the underlying data available for recovery.
posted by k3ninho at 4:15 PM on October 2, 2021 [1 favorite]

Another option would be to arrange with the shop that you will be returning the system without its drive, and that they supply you with a replacement system that has had a similar driveectomy.
posted by Stoneshop at 2:25 AM on October 4, 2021