Security Basics mailing list archives

RE: password protection in office XP documents


From: security () rexwire com
Date: Wed, 18 Jun 2003 12:07:59 -0400

 No one is claiming that printing is compromising content integrity. People
protect content in document to stop it from being alerted other wise why
else would they go through the effort of protecting? A protected document
should remain protected in its own framework. What I mean by this is that;
if Word is used to protect certain parts of a document than it should not be
possible to use Word to unprotect that document just by saving in a
different format. A PDF is a good example. Once you set security on the PDF
document all PDF readers honor that security they don't let you save it as a
html. (there are tools to unlock PDF but they are beyond the scope of this
conversation)


Hope that brings out my original point.


-SKP

-----Original Message-----
From: Brian Eckman [mailto:eckman () umn edu] 
Sent: Wednesday, June 18, 2003 9:00 AM
To: security () rexwire com; leifg () doh state nm us;
security-basics () securityfocus com
Subject: Re: password protection in office XP documents


I did copy the contents of a "protected" file (not the full password 
protection - the changes protection that Leif discussed) into a new doc 
and save it before I wrote the message. In fact, I just did it again 
before I sent this message. Then I modified the new doc and saved it 
again. Then I saved it over the old file just for fun.

Now at first glance, it appears like the original document to everyone 
else. I can set my own protection password too, so nobody except maybe 
eventually the original document owner will know the difference. It took 
seconds to accomplish. This was in Word XP fully patched.

How is the data "compromised" by saving it into a different format, and 
a different file, while the original document that everyone else uses is 
intact? If I print the document out, use some "white out" and type over 
it with my typewriter, I could argue that it has been "compromised" too. 
Should we report to Microsoft that printing files is a security flaw?

Brian


security () rexwire com wrote:
You cant copy a file that is protected. I do think letting someone save a
protected file in another format (Html) is dumb. I don't care if the
argument is that the original file is still protected. The goal is to
protect the data and the data is compromised once the file is saved in a
different format.


-SKP

-----Original Message-----
From: Brian Eckman [mailto:eckman () umn edu] 
Sent: Tuesday, June 17, 2003 4:17 PM
To: Leif Gregory; security-basics () securityfocus com
Subject: Re: password protection in office XP documents




Leif Gregory wrote:

Hello Brian,

Tuesday, June 17, 2003, 7:46:42 AM, you wrote:
BE> Gosh, if I wanted to bypass those, I'd copy the existing Office
BE> file into a new one and make my changes, then save it over the old
BE> one. Seems like it would be a quicker "hack", and would be easier
BE> for most people than saving it as HTML and editing the source
BE> code, then saving it back as an Office file.

BE> Now, one could get into file system rights arguments, but if you save

it

BE> as HTML, you are creating a new file. Now there will be a .doc and an
BE> .html, and if you have rights to turn the .html back into the .doc,

then

BE> you can do what I mentioned above as well.

BE> I still fail to see any flaw here. What was reported is opening the

HTML

BE> file in Office and the protection is gone. The HTML file is a *new*

file

BE> that you created; the original Office file still has the protection.

But see, it's not a file rights issue. It's an XML document property
tag (if that is the right terminology). It's an integral piece of the
Word document. Copying it retains the document properties, therefore
the protection. Converting it to HTML brings the document properties
into plaintext, which you can highlight and delete.


(mass snippage)

Leif & list,

Sorry, I wasn't clear. I wasn't talking about copying the file, I was 
talking about copying the contents of the file. Using a Word doc as an 
example, I would take the Word doc, highlight everything, copy and paste 
it into a new Word doc and save it over the original "protected" 
document. It would be a heck of a lot faster than the methods that have 
been described.

Brian



-- 
Brian Eckman
Security Analyst
OIT Security and Assurance
University of Minnesota
612-626-7737

"There are 10 types of people in this world. Those who
understand binary and those who don't."


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