Re: [EXT] [qubes-users] The safest way to search in files on an external hard drive

2021-06-09 Thread haaber

On 6/9/21 10:46 PM, Ulrich Windl wrote:

On 5/31/21 4:55 PM, Michael Singer wrote:

Dear Qubes community,

I am looking for a really secure way to use Qubes for searching not
only a hard drive for file names, but for text that is in files.

The goal is to avoid an exploit in the searched files leading to a
takeover of the hard drive by malware.


If your app is working on the disk device and the app only has read
access to it, it'll be quite unlikely that the disk device will be changed.
Likewise if you mount the filesystem read-only, and the user running the
app is unable to re-mount, it's also quite unlikely that the disk will
be changed. You could even try to combine both methods (read-only mount
a read-only block device). However not all filesystems work on a
write-protected block device.


A variant: mount it RO in AppVM1, then attach it to AppVM2 (which by no
means can "remount -rw" it unless interVM-barriers are breached (and
game is over anyways).

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Re: [EXT] [qubes-users] The safest way to search in files on an external hard drive

2021-06-09 Thread Ulrich Windl

On 5/31/21 4:55 PM, Michael Singer wrote:

Dear Qubes community,

I am looking for a really secure way to use Qubes for searching not only a hard 
drive for file names, but for text that is in files.

The goal is to avoid an exploit in the searched files leading to a takeover of 
the hard drive by malware.


If your app is working on the disk device and the app only has read 
access to it, it'll be quite unlikely that the disk device will be changed.
Likewise if you mount the filesystem read-only, and the user running the 
app is unable to re-mount, it's also quite unlikely that the disk will 
be changed. You could even try to combine both methods (read-only mount 
a read-only block device). However not all filesystems work on a 
write-protected block device.

You could also try to find a hardware solution setting the drive read-only.



The total size of all my files is too large for me to put them all in one qube 
before searching for text in them.

Would it perhaps be possible to mount only a single partition of the hard drive 
into a qube, but not with write permissions, only read permissions?

I would do the search on command line, using "grep" for plain text files, 
"pdfgrep" for PDFs, and something for table files, databases, etc.

Is my idea feasible? And how secure would it be?

Best regards
Michael Singer



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