[Xerte-dev] Re: SECURITY PATCH for upload.php

Fri Mar 8 12:08:27 GMT 2013

If we are going down this route then should we also post the allowed extensions with the file so that upload can check it meets the criteria for the individual model?  Although it would be trivial to overcome this using an exploit, we'd still have the complete whitelist superset to prevent injection of potentially malicious file types... I suppose with the html5 files Easter deadline coming up we have javsacript XSS to think about too... if for example sake you could get them a js file onto the Nottingham install you could ajax anything in the same domain as if the user running the LO had actioned it... if that was Fay or Julian then what could you get access to?

Regards,

John Smith
Learning Technologist
School of Health & Life Sciences
Glasgow Caledonian University

From: xerte-dev-bounces at lists.nottingham.ac.uk [mailto:xerte-dev-bounces at lists.nottingham.ac.uk] On Behalf Of Tom Reijnders
Sent: Friday, March 08, 2013 11:19 AM
To: For Xerte technical developers
Subject: [Xerte-dev] Re: SECURITY PATCH for upload.php

If we are going down this road, it will make more sense to me to have them in the .xwd (because the .xwd will present the browse button and the upload action)

Tom
Op 8-3-2013 12:09, Fay Cross schreef:
I don't know how all this side of things works tbh. If it makes more sense from your side of things to have the info in the model files rather than xwd then let me know what you need and I can put it in

From: xerte-dev-bounces at lists.nottingham.ac.uk<mailto:xerte-dev-bounces at lists.nottingham.ac.uk> [mailto:xerte-dev-bounces at lists.nottingham.ac.uk] On Behalf Of Smith, John
Sent: 08 March 2013 10:27
To: For Xerte technical developers
Subject: [Xerte-dev] Re: SECURITY PATCH for upload.php

Hi Fay,

Sure, I could work with that if that's not going to cause any problems with the system. I think we need to check mime types too as  the server can ignore extensions if it recognizes the format but if we have the extensions allowed then I suppose we can look up the mime types allowed for that extension and make sure the uploaded file type matches...

These parameters won't be posted with the file will they, if they are added there? The only issue I see is that we would simply have an aggregated  list of extensions that ALL models use, and so any model could upload any file in that list, not just the ones allowed by that model, which is kind of counter intuitive...

Regards,

John

From: xerte-dev-bounces at lists.nottingham.ac.uk<mailto:xerte-dev-bounces at lists.nottingham.ac.uk> [mailto:xerte-dev-bounces at lists.nottingham.ac.uk] On Behalf Of Fay Cross
Sent: Friday, March 08, 2013 10:15 AM
To: For Xerte technical developers
Subject: [Xerte-dev] Re: SECURITY PATCH for upload.php

If we added something to the xwds would that help?

e.g. adding an extra attribute...
<url label="Image" type="media" fileType="jpeg,gif,png"/>

From: xerte-dev-bounces at lists.nottingham.ac.uk<mailto:xerte-dev-bounces at lists.nottingham.ac.uk> [mailto:xerte-dev-bounces at lists.nottingham.ac.uk] On Behalf Of Smith, John
Sent: 08 March 2013 10:00
To: For Xerte technical developers
Subject: [Xerte-dev] Re: SECURITY PATCH for upload.php

Could we add a comment type header block to the start of the models? Similar to a Wordpress style header and parse these comments once in a while, via cron or just on user login or something? I suppose we could hook 'user_login' and do the damage in a plugin?

Do you think that a comment header would that break the parsing of the model?

Regards,

John Smith
Learning Technologist
School of Health & Life Sciences
Glasgow Caledonian University

From: xerte-dev-bounces at lists.nottingham.ac.uk<mailto:xerte-dev-bounces at lists.nottingham.ac.uk> [mailto:xerte-dev-bounces at lists.nottingham.ac.uk] On Behalf Of Pat @ Pgogy
Sent: Thursday, March 07, 2013 5:14 PM
To: For Xerte technical developers
Subject: [Xerte-dev] Re: SECURITY PATCH for upload.php

Hello,

Problem is getting a list of types the models support. I think there is a case for saying the model should list the extensions it supports as it is partly their job to do it. This way the model could post the allowed types and the list is generated on the fly?

I agree preventing php is a good thing, but I think the problem is not knowing what types are acceptable is a real curveball

Pgogy Webstuff - http://www.pgogywebstuff.com
Makers of web things of a fair to middling quality

On 7 Mar 2013, at 15:32, "Smith, John" <J.J.Smith at gcu.ac.uk<mailto:J.J.Smith at gcu.ac.uk>> wrote:
Hi Pat,

I didn't copy your regexp or your select list directly but translated the select code into a comma separated list so that it can be moved elsewhere if required...

I noticed the list in the sitedetails table but it is of Mime Types. I think it would be best practice to use extensions, content headers, mimetypes and any other method available to whitelist the allowable files but I think that might take a bit more work...

I think it is leaving a load of sites out there very vulnerable so we should try to  find a good way to shore this up before the next release. What do you think? I'll have a go at adding in some code to deal with content headers and mimetypes

Regards,

John Smith
Learning Technologist
School of Health & Life Sciences
Glasgow Caledonian University

From: xerte-dev-bounces at lists.nottingham.ac.uk<mailto:xerte-dev-bounces at lists.nottingham.ac.uk> [mailto:xerte-dev-bounces at lists.nottingham.ac.uk] On Behalf Of Pat @ Pgogy
Sent: Thursday, March 07, 2013 2:54 PM
To: For Xerte technical developers
Subject: [Xerte-dev] Re: SECURITY PATCH for upload.php

Hello,

I hobble the Wordpress version deliberately to only allow a few file types but that isn't the list that full XOT needs (there is in fact, no list, hence the problem).

My reg exp is a bit flaky as well, if you copied that over.

There is a sort of whitelist in the sitedetails table as the media upload properties panel page uses this - but not sure this is the XOT list.

Pgogy Webstuff - http://www.pgogywebstuff.com
Makers of web things of a fair to middling quality

On 7 Mar 2013, at 13:01, "Smith, John" <J.J.Smith at gcu.ac.uk<mailto:J.J.Smith at gcu.ac.uk>> wrote:
Hi,

I've just committed a change to upload.php (revision 714) to stop users exploiting a system by uploading php code. I've added a whitelist and stuck in the same allowed file extensions that Pat uses in the Wordpress plugins.

Can someone test this and advise if there are any other media types that we want/need to allow?

There was also a session check but exit(); was commented out therefore in an unpatched system ANYONE can post data to upload.php and get some code onto the server. I've uncommented this now but does anyone know why it was commented out in the first place?

Regards,

John Smith
Learning Technologist
School of Health & Life Sciences
Glasgow Caledonian University

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