hacked by the (alleged) `amazon-security' scammers

[Ralf Mardorf]

On Sun, 07 Nov 2021 10:22:24 -0500, hput via ubuntu-users wrote:
>Anyone here that can coach me a little about how to go about getting
>the disks securely wiped.

Hi,

you much likely can't do that. All drives (not only shingled magnetic
recording hard disk drives and solid state drives) manage storage by the
firmware. Drives have got zones with copies of data, that you can't
access targeted by the host's software. Using manufacturer utilities
might be able to do the job, but I wouldn't trust those tools.

If you should consider to use shred...

$ apropos shred
shred (1)            - overwrite a file to hide its contents, and optionally delete it

...overwriting items just one time is enough. It makes not much sense to
overwrite items several times.

"Limitations
A limitation of shred when invoked on ordinary files is that it only
overwrites the data in place without overwriting other copies of the
file. Copies can manifest themselves in a variety of ways, such as
through manual and automatic backups, file system snapshots,
copy-on-write filesystems, wear leveling on flash drives, caching such
as NFS caching, and journaling. All limitations imposed by the file
system can be overcome by shredding every device on which the data
resides instead of specific files. However, since wear leveled devices
do not guarantee a fixed relationship between logical blocks
addressable through the interface and the physical locations in which
the data is stored, shredding may not provide adequate security. If
available, the SATA secure erase command, issued through hdparm or a
similar utility, may be helpful in this situation. Even for magnetic
devices, SATA secure erase will be faster and more reliable than
shredding. Physical destruction may be necessary to securely erase
devices such as memory cards and unusable hard disks." -
https://en.wikipedia.org/wiki/Shred_(Unix)#Limitations

Regards,
Ralf