Technology in terms you understand. Sign up for the Confident Computing newsletter for weekly solutions to make your life easier. Click here and get The Ask Leo! Guide to Staying Safe on the Internet — FREE Edition as my thank you for subscribing!

Is remote printing secure?

I use a printer at the office that is hooked to the network. Am I correct
that there is a print job log that shows what each printer in the office
prints? Or, can only a separate network server create print job logs. If any
network automatically does show a print job by any of the office computers,
what are some basic information shown in the log and can an administrator print
a document that has been printed if they see it on a print job log?

Yes, there can be logs. No, previously printed documents are not saved in a way
that they could be re-printed or viewed again later.

However (isn’t there’s always a “however”?), depending on your level of
concern, printing may not be as secure as we casually assume.

Become a Patron of Ask Leo! and go ad-free!

First the log.

The computer that a printer is connected to can be configured to log all
printing events to the System log. You can use Window’s Event Viewer on that
machine to see what documents have been printed, and by what user.

For example, I just printed a test document, and in the event log I found
this:

Printing Event in the Event Log

That log can contain the name of your document, as well as the computer name
and user name of the account printing it. If the printer is shared, of course
the computer name would be the name of the remote computer accessing the shared
printer.

So, yes, while logs aren’t guaranteed to exist (mine was off by default),
they certainly can be enabled, and can contain some interesting
information.

Next we need to examine exactly how printing works.

When you print a document it invokes something called the “print spooler”.
Rather than printing directly to the printer, the information that would be
sent to the printer is actually written to (or “spooled”) to disk, and sent on
from there. Your application writes the printed document to the print spooler
where it’s placed in the queue of documents waiting to be printed. As prior
documents finish printing yours moves ahead in the list, and finally prints
when its turn comes.

If the printer is remote – meaning that you’re printing on machine A to a
printer connected to and shared by machine B, then your document’s print data
is written to the spooler file on machine B.

Regardless of where the spooled file lives, once your document has been
printed, that file is deleted. There’s no record of its content kept, and
there’s no way to simply say “print it again”.

Or is there?

This is where judicious paranoia might set in.

We all know by now that files aren’t really deleted, the disk space they
used is simply marked as “available to be overwritten”. Until that disk space
is overwritten – you guessed it – the data could be
recovered. It wouldn’t be easy, and on a busy system it might not even be
likely, but there is a possibility.

(Note that I’m talking about printers “shared” through another Windows
computer. Printers attached directly to a network may, or may not, contain a
log, and may, or may not, spool the documents to internal storage in a way that
might be recovered later. It all depends on their configuration and
abilities.)

So, what can you do?

Nothing, really. When you send data to another computer, any other computer,
you’re ultimately entrusting the owner of that computer with the possibility of
full access to your data and printing to a shared printer is no different.

This is one case where even encryption won’t help; your printed document
still needs to be decrypted on the remote computer in order to be
printed.

If you really need to keep that data super secure and avoid even
the slimmest chance of recovery by others, then the only real approach would be
to print it only on a computer that you control. (And consider securely wiping
the disk’s free space when you’re done, just in case.)

Subscribe to Confident Computing! Tech problem solving & safety tips & a weekly confidence boost in your inbox every week.

I'll see you there!

10 Reasons Your Computer is Slow

Slow Computer?

Speed up with my special report: 10 Reasons Your Computer is Slow, now updated for Windows 10.

NOW: name your own price! You decide how much to pay -- and yes, that means you can get this report completely free if you so choose. Get your copy now!

1 thought on “Is remote printing secure?”

Leave a reply:

Before commenting please:

  • Read the article.
  • Comment on the article.
  • No personal information.
  • No spam.

Comments violating those rules will be removed. Comments that don't add value will be removed, including off-topic or content-free comments, or comments that look even a little bit like spam. All comments containing links and certain keywords will be moderated before publication.

I want comments to be valuable for everyone, including those who come later and take the time to read.