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Issue metadata

Status: Fixed
Owner:
Closed: Apr 2017
Cc:



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Windows: Dolby Audio X2 Service EoP

Project Member Reported by forshaw@google.com, Jan 10 2017

Issue description

Windows: Dolby Audio X2 Service Elevation of Privilege
Platform: Windows 10 + Realtek Audio Driver version 6.0.1.7898 (on a Lenovo P50). Version of the service binary 0.7.2.61 built on 7/18/2016.
Class: Elevation of Privilege

Summary:
The DAX2API service installed as part of the Realtek Audio Driver on Windows 10 is vulnerable to a privilege escalation vulnerability which allows a normal user to get arbitrary system privileges.

Description:

The DAX2API service is a DCOM service written in .NET running at system privileges. The use of .NET for DCOM is inherently unsafe and should not be used. There’s public exploit code to elevate privileges on arbitrary services available at https://github.com/tyranid/ExploitDotNetDCOM.

Microsoft recommends moving from using DCOM to WCF for .NET services of different privilege levels. See https://blogs.technet.microsoft.com/srd/2014/10/14/more-details-about-cve-2014-4073-elevation-of-privilege-vulnerability/ for more information.

Proof of Concept:

To demonstrate the vulnerability download the project https://github.com/tyranid/ExploitDotNetDCOM and compile using Visual Studio. The executable to use is ExploitDotNetDCOMSerialization.exe.

1) From a command prompt run the command “ExploitDotNetDCOMSerialization.exe 6A28A945-790C-4B68-B0F4-34EEB1626EE3 notepad” 
2) Check the currently running processes for the privileged copy of notepad,

Expected Result:
No privilege escalation occurs.

Observed Result:
An instance of notepad is running at system privileges.

This bug is subject to a 90 day disclosure deadline. If 90 days elapse without a broadly available patch, then the bug report will automatically become visible to the public.


 
Project Member

Comment 1 by forshaw@google.com, Mar 16 2017

Labels: Deadline-Grace
Lenovo have requested the grace period. Their plan is to release the patch on 20th April.
Project Member

Comment 2 by forshaw@google.com, Mar 28 2017

Labels: -Vendor-Lenovo Vendor-Dolby
I've changed the vendor to indicate that this isn't really specific to Lenovo, they just made the first product I discovered the issue on. The vulnerable code is developed by Dolby, but not distributed directly to end users. Instead the fix will be distributed by OEMs for each device, therefore users will need to contact their OEMs if they have a vulnerable version of the Dolby software for an update.
Project Member

Comment 3 by forshaw@google.com, Mar 30 2017

Labels: CVE-2017-7293
Project Member

Comment 4 by forshaw@google.com, Apr 24 2017

Project Member

Comment 5 by forshaw@google.com, Apr 24 2017

Labels: -Restrict-View-Commit
Project Member

Comment 6 by forshaw@google.com, Apr 27 2017

Lenovo have released an advisory for issues related to their products.

https://support.lenovo.com/gb/en/product_security/len-12704

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