Hi,
I've formatted the cells as date mm/dd/yy and entered the values as is. Also tried by preceeding with equal sign in case deemed to be a formula but neither works.
I assume a difference between two days yields the difference in days, correct? Or are the formula different than plain math?
Eduard
the Osborne guy at last meeting
On 2019-05-15 eh@eduardhiebert.com wrote:
Hi,
I've formatted the cells as date mm/dd/yy and entered the values as is. Also tried by preceeding with equal sign in case deemed to be a formula but neither works.
I assume a difference between two days yields the difference in days, correct? Or are the formula different than plain math?
I guess this is a follow-up from the meeting? (Sorry, wasn't there.)
What is it you're trying to do? Post the formula you are putting in the cell.
Hi,
Without opening a pdf, attached to an email but simply using my computer's print option, is there still a risk of some kind of infection?
I ask as some time I asked the question whether opening a pdf could compromise my computer and the best advise at the time was that it was possible.
Thanks,
Eduard
Maybe.
For starters, the PDF to be printed has to land on your computer before it can be printed. Either you are saving it explicitly, or a temporary ("hidden") copy is landing somewhere in your files/folders structure.
Now, a file saved on the computer cannot itself act virally, no matter how "infected" it is. Its viral content needs to get executed somehow, and the many mechanisms to achieve that is a long story.
Next, you can't send a stored/saved PDF to a printer, because printers don't understand PDF. So, you end up (either explicitly or by some automation) opening the PDF in a PDF reader/viewer like Adobe Acrobat Reader or a myriad of other readers/viewers, and from there, you get to print the PDF via the usual print options found in most software.
So, the only danger is in the reader/viewer software, that could potentially be tricked into executing the viral content in a PDF. I'm not well-versed in the latest PDF standards, as to what forms of executable content they can handle, but that's where the only danger lies. I expect that other folks here can enlighten us on that detail.
Hartmut
On Sun 07 May 2023 at 17:00:08 -05:00, eh@eduardhiebert.com wrote:
Hi,
Without opening a pdf, attached to an email but simply using my computer's print option, is there still a risk of some kind of infection?
I ask as some time I asked the question whether opening a pdf could compromise my computer and the best advise at the time was that it was possible.
Thanks,
Eduard
Roundtable mailing list Roundtable@muug.ca https://muug.ca/mailman/listinfo/roundtable
PDFs have been known to contain malicious payloads. However, if your software is up to date (patched), and you don't click on anything in the PDF, then printing it should be a low risk activity. -Adam Get Outlook for Androidhttps://aka.ms/AAb9ysg ________________________________ From: Roundtable roundtable-bounces@muug.ca on behalf of eh@eduardhiebert.com eh@eduardhiebert.com Sent: Sunday, May 7, 2023 5:00:08 PM To: Continuation of Round Table discussion roundtable@muug.ca Subject: [RndTbl] Is printing a pdf attached to an email safe?
Hi,
Without opening a pdf, attached to an email but simply using my computer's print option, is there still a risk of some kind of infection?
I ask as some time I asked the question whether opening a pdf could compromise my computer and the best advise at the time was that it was possible.
Thanks,
Eduard
_______________________________________________ Roundtable mailing list Roundtable@muug.ca https://muug.ca/mailman/listinfo/roundtable
Adam, Hartmut,
With the caveats detailed by each of you I'll side on the side of caution and via public 411 #'s get the party to confirm its theirs.
My thanks to each of you!
Eduard
On 2023-05-07 Adam Thompson wrote:
PDFs have been known to contain malicious payloads. However, if your software is up to date (patched), and you don't click on anything in the PDF, then printing it should be a low risk activity.
PDFs are still a very popular virus vector. But they are mostly attacking older Adobe Reader on Windows. So in that sense you're already much safer on linux (assuming that's what you're talking about) because a) the specific obscure linux viewer / pdf library isn't a popular target, and b) linux itself isn't a popular target of these types of attack. The attack would have to trigger some sec flaw in the reader and then also use that flaw to execute linux-compatible code. The odds of these together is quite small.
You *can* directly print a PDF (say from the command line) on linux, and at that time it'll go through cups / ghostscript to render the PDF into a raster, or into PS/PCL. So even doing it "without a reader/viewer" can be subject to attack. (Because in this case there is a reader/viewer (ghostscript), it's just hidden from you.)
The only downside to linux for PDFs is, while they aren't popular vectors, their pdf viewers (all mostly obscure hobby projects) also receive less sec reviews and updates. And I bet they mostly share just 1 or 2 base pdf libraries, and the same may apply to them.
A safe option would be to open the pdf in a throwaway VM or in (my favorite) a firejail instance. You could use a heavily-locked down firejail to use pdftoppm to sanitize the pdf into a raster-only format that you can then 100% safely view and manipulate outside the jail with your normal tools.
P.S. I would never open a PDF I didn't somewhat trust on Windbloze. I would open most PDFs that didn't come from shady-looking sources in linux viewers. If it was from a very shady source I'd use the firejail trick. You're right to be suspicious; always be suspicious!! But don't let it stop you from getting things done.
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Adam Thompson -
eh＠eduardhiebert.com -
Hartmut W Sager -
Trevor Cordes