=======
Summary
=======
Name: SharePoint Team Services source code disclosure through download
facility
Release Date: 21 October 2009
Reference: NGS00532
Discover: Daniel Martin <daniel@ngssoftware.com>
Vendor: Microsoft
Systems Affected: SharePoint 2007 (12.0.0.6219, 12.0.0.4518 and
possibly others)
Risk: Medium
Status: Reported

========
TimeLine
========
Discovered: 17 September 2008
Released:  2 October 2008
Approved:  3 October 2008
Reported:  8 October 2008
Fixed:
Published: 23 October 2009

===========
Description
===========
Microsoft SharePoint is a browser-based collaboration and document
management platform. It can be used to host web sites that access shared
workspaces and documents, as well as specialized applications like wikis
and blogs from a browser.

It was found that the download facility of Microsoft SharePoint Team
Services can be abused to reveal the source code of ASP.NET files.

=================
Technical Details
=================
SharePoint Team Services stores a variety of files in its backend
database. These files include site templates, custom ASP.NET pages and
documents that users of the application upload to the document libraries.

Insufficient validation in the input parameters of the download facility
can result in the source code of ASP.NET files being disclosed. For
example, the source code of the default ASP.NET page available after
installing the product (http://server/Pages/Default.aspx) can be obtained
by issuing the following request:

http://server/_layouts/download.aspx?SourceUrl=/Pages/Default.aspx&Source=http://server/Pages/Default.aspx&FldUrl=

In order to retrieve the source code any file stored in the backend
database (files whose path does not start with /_layout/) it is sufficient
to craft a request that follows this pattern:

http://server/_layouts/download.aspx?SourceUrl=<relative_path>&Source=<full_path>&FldUrl=

This bug can result in disclosure of sensitive information that can be
used by an attacker targeting the system. For instance the PublicKeyTokens
of the ASP.NET assemblies deployed in the server can be revealed enabling
an attacker to upload a malicious file that makes use of them.

===============
Fix Information
===============
It is advised that the source code of any bespoke ASP.NET file deployed
in the system is reviewed to ensure that no sensitive information would
be reviewed if an attacker abuses the download facility of the framework.
Additionally access on a need-to-know basis to SharePoint systems is
advised.

No workarounds exist at this point. However Microsoft has been contacted
so they can produce a fix for their customers. NGS has been advised that
although this issue will not be patched until the next release of
SharePoint, Microsoft has addressed the design issues around it in a
Knowledge Base article (KB976829) about security considerations when
running SharePoint that can be found at:

http://go.microsoft.com/fwlink/?LinkId=167936

NGS Software wants to thank the MSRC team and Charles Weidner in
particular for their support in clarifying this issue.

NGSSoftware Insight Security Research
http://www.ngssoftware.com/
http://www.databasesecurity.com/
http://www.nextgenss.com/
+44(0)208 401 0070

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