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M5Marco Author

Level 1

37 points

Erasing Hard Drive - No More "Secure" Options?

I had 10.11.1 installed and decided to wipe the hard drive clean and reinstall the OS fresh. So I went about doing just that. I noticed Apple revamped Disk Utility. When attempting to erase the hard drive I did not see any options to securely erase it. Back on Yosemite I had the option to wipe the drive according to different industry security standards (7 rewrite passes of the drive being most secure option).

EL Capitan only provided me with a simple "erase" function that wiped the entire drive within seconds and that was that. So i am wondering if I might have simply missed where the erase security options are, or if Apple removed them entirely?

Thanks in advance for responses.

Posted on Nov 1, 2015 10:45 PM

Top-ranking reply

MrHoffman

Community+ 2024

Level 10

127,309 points

Posted on Nov 2, 2015 2:36 PM

Per Apple, Secure Delete does not work on SSD devices, and accordingly has been removed. The associated details were in a security report
identified as CVE-2015-5901, and this behavior is specifically mentioned in About the security content of OS X El Capitan v10.11 - Apple Support.

SSD doesn't deletem doesn't erase and doesn't overwrite in the same way as hard disks did, so overwrites are — until you flush the entire cache of TRIMmed data within the SSD repeatedly — futile. What you asked to have multiply-overwritten — until the cache of pre-erased "free space" has been repeatedly flushed — hasn't been.

The whole basis for using multiple overwrites — that the exactly read-write head alignments varied slightly on hard disks, and you could potentially access deleted data by offsetting the heads slightly — also does not apply to SSDs.

Simply deleting the SSD data with whole-disk encryption will get most folks where they want to be here.

If you're still working with hard disks, then you can use the srm command.

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32 replies

M5Marco Author

Level 1

37 points

Nov 2, 2015 2:11 PM in response to R C-R

What I need can always come with me through cloud services, USB drive, etc. But the drive itself needs to be secured if I were ever to part with it of course.

babowa

Level 9

78,441 points

Nov 2, 2015 2:18 PM in response to M5Marco

From my perspective: absolutely, yes. That is all I've ever used for an erase and install (if I'm not selling it). The data will be overwritten sooner or later on a regular HD - SSD not so much.

Erasing Hard Drive - No More "Secure" Options?