April 11, 2017—KB4015550 (Monthly Rollup)

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Release Date:

Apr 11, 2017

Version:

Monthly Rollup

Improvements and fixes

This security update includes improvements and fixes that were a part of update KB4012219 (released March 21, 2017) and resolves the security vulnerabilities in Hyper-V, libjpeg image-process library, Win32K, Adobe Type Manager font driver, Active Directory Federation Services, Lightweight Directory Access Protocol, Windows kernel-mode drivers, OLE, Scripting Engine, Windows Graphics component and Internet Explorer in addition to these quality improvements:

Addressed an issue that was causing Authentication Success and Failure events with Event ID 4768 to not be logged after installing KB4012216.
Addressed a bug check encountered on Windows Server 2012 R2 Hyper-V hosts with error code 0xE4 after installing KB4012216.
Addressed issue where a server may fail with STOP 0x3B error leading to data loss when Input Method Editors (IME) like keyboards are installed.

For more information about the security vulnerabilities resolved, please refer to the Security Update Guide.

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Known issues in this update

Symptom	Workaround / Resolution
If the PC uses an AMD Carrizo DDR4 processor, installing this update will block downloading and installing future Windows updates.	This issue is resolved by KB4022726.
If a Server 2012 R2 system uses an Intel Xeon (E3 v6) family of processors, installing this update will block downloading and installing future Windows updates.	This issue is resolved by KB4022726.
This security update introduced an issue in which, if an iSCSI target becomes unavailable, attempts to reconnect will cause a leak. Initiating a new connection to an available target will work as expected.	Microsoft is working on a resolution and will provide an update in an upcoming release. For more information about this issue, see the following section.

More information about the iSCSI issue

Windows Server 2012 R2 and Server 2016 computers that experience disconnections to iSCSI attached targets may show many different symptoms. These include, but are not limited to:

The operating system stops responding
You receive Stop errors (Bugcheck errors) 0x80, 0x111, 0x1C8, 0xE2, 0x161, 0x00, 0xF4, 0xEF, 0xEA, 0x101, 0x133, or 0xDEADDEAD.
User log on failures occur together with a "No Logon Servers Available" error.
Application and service failures occur because of ephemeral port exhaustion.
An unusually high number of ephemeral ports are being used by the System process.
An unusually high number of threads are being used by the System process.

Cause

This issue is caused by a locking issue on Windows Server 2012 R2 and Windows Server 2016 RS1 computers, causing connectivity issues to the iSCSI targets. The issue can occur after installing any of the following updates:

Windows Server 2012 R2

Release date	KB	Article title
May 16, 2017	KB 4015553	April 18, 2017—KB4015553 (Preview of Monthly Rollup)
May 9, 2017	KB 4019215	May 9, 2017—KB4019215 (Monthly Rollup)
May 9, 2017	KB 4019213	May 9, 2017—KB4019213 (Security-only update)
April 18, 2017	KB 4015553	April 18, 2017—KB4015553 (Preview of Monthly Rollup)
April 11, 2017	KB 4015550	April 11, 2017—KB4015550 (Monthly Rollup)
April 11, 2017	KB 4015547	April 11, 2017—KB4015547 (Security-only update)
March 21, 2017	KB 4012219	March 2017 Preview of Monthly Quality Rollup for Windows 8.1 and Windows Server 2012 R2

Windows Server 2016 RTM (RS1)

Release date	KB	Article title
May 16, 2017	KB 4023680	May 26, 2017—KB4023680 (OS Build 14393.1230)
May 9, 2017	KB 4019472	May 9, 2017—KB4019472 (OS Build 14393.1198)
April 11, 2017	KB 4015217	April 11, 2017—KB4015217 (OS Build 14393.1066 and 14393.1083)

Verification

Verify the version of the following MSISCSI driver on the system:

c:\windows\system32\drivers\msiscsi.sys

The version that will expose this behavior is 6.3.9600.18624 for Windows Server 2012 R2 and version 10.0.14393.1066 for Windows Server 2016.

The following events are logged in the System log:

Event source	ID	Text
iScsiPrt	34	A connection to the target was lost, but the Initiator successfully reconnected to the target. Dump data contains the target name.
iScsiPrt	39	The Initiator sent a task management command to reset the target. The target name is given in the dump data.
iScsiPrt	9	Target did not respond in time for a SCSI request. The CDB is given in the dump data.

Review the number of threads that are running under the System process, and compare this to a known working baseline.
Review the number of handles that are currently opened by the System process, and compare this to a known working baseline.
Review the number of ephemeral ports that are being used by the System process.
From an administrative Powershell, run the following command:

Get-NetTCPConnection | Group-Object -Property State, OwningProcess | Sort Count

Or, from an administrative CMD prompt, run the following NETSTAT command together with the "Q" switch. This shows "bound" ports that are no longer connected:

NETSTAT –ANOQ

Focus on ports that are owned by the SYSTEM process.

For the three previous points, anything more than 12,000 should be considered suspect. If iSCSI targets are present in the computer, there is high probability that the issue will occur.

Resolution

If the event logs indicate that many reconnections are occurring, work with your iSCSI and network fabric vendor to help diagnose and correct the reason for the failure to maintain connections to iSCSI targets. Make sure that iSCSI targets can be accessed over the current network fabric. Install updated fixes when they become available. This article will be updated with the specific KB article number of the fix to install when it becomes available.

Note We do not recommend that you uninstall any of the March, April, May, or June security rollups. Doing so will expose the computers to known security exploits and other bugs that are mitigated by monthly updates. We recommend that you first work with iSCSI target and network vendors to resolve the connectivity issues that are triggering target reconnects.

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How to get this update

This update will be downloaded and installed automatically from Windows Update. To get the stand-alone package for this update, go to the Microsoft Update Catalog website.

Prerequisites
To apply this update, you must have Windows 8.1 and Windows Server 2012 R2 update: April 2014 (KB2919355) installed.
File information
For a list of the files that are provided in this update, download the file information for update 4015550.

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More Information

The security fixes that are listed in this Security Monthly Quality Rollup KB4015550 are also included in the April 2017 Security Only Quality Update, KB4015547, except for the security fixes for Internet Explorer. Those are instead included in the Cumulative Security Update for Internet Explorer KB4014661. Installing either this April 2017 Security Monthly Quality Rollup, or both the April 2017 Security Only Quality update and the Cumulative Security Update for Internet Explorer, will install the security fixes that are listed here. This Security Monthly Quality Rollup also includes improvements and fixes from previous monthly rollups.
If you use update management processes other than Windows Update, and you automatically approve all security update classifications for deployment, April 2017 Security Monthly Quality Rollup KB4015550, April 2017 Security Only Quality Update KB4015547, and the Cumulative Security Update for Internet Explorer KB4014661 are deployed. We recommend that you review your update deployment rules to make sure that the desired updates are deployed.

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