Stuff I'm Up To

Technical Ramblings

SMB Insecurely Configured Service — August 17, 2017

SMB Insecurely Configured Service

For the first time today I ran into Nessus plugin ID 44676.

It highlighted an “insecurely configured Windows service”. This related to a Service Discretionary Access Control List (DACL), which is a whole bag of new to me.

The guidance shows how you can use the command line to show the DACL for the service it reported the issue with.

The following service has insecure group permissions:

Bacway Windows Service (BacwayService) :
– Authenticated Users: DC

More information is given here: https://support.microsoft.com/en-us/help/914392/best-practices-and-guidance-for-writers-of-service-discretionary-acces

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Flash Update KB4034662 —

Flash Update KB4034662

Two of our Windows 2012R2 servers constantly failed to apply Windows Updates. They’d start deploying the updates but every time a reboot was required the updates would all roll back.

After several weeks of various members of the IT team banging their heads on their desks and the walls, I stepped up and took a look at the problem. It was a real doozy. Took me ages trying to figure out what was going on.

It all turned out to be down to one update for Flash player! We don’t even use flash player on any of the servers.

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VCSA 6.0 U3b to 6.5 U1 — August 10, 2017

VCSA 6.0 U3b to 6.5 U1

So far this upgrade seems to frustrating straight out of the box! We already run a VCSA (vCenter Server Appliance) and the process should be to automatically deploy a new VCSA and migrate the data from the old to the new and then power down the old. All from the Windows GUI installer.

But it fails to deploy with an unknown error.

If you save and view the installer log it becomes abundantly clear what the failure is. The installer is trying to issue a ‘date’ command at the current VCSA’s command line, and fails because it’s expecting a BASH shell and instead it is getting the default vCenter shell where the BASH shell is disabled.

2017-08-10T07:56:13.446Z - info: VM Identifier for Source VC: 78
2017-08-10T07:56:13.570Z - debug: initiateFileTransferFromGuest error: ServerFaultCode: A general system error occurred: Unknown error
2017-08-10T07:56:13.573Z - debug: Failed to get fileTransferInfo:ServerFaultCode: A general system error occurred: Unknown error
2017-08-10T07:56:13.573Z - debug: Failed to get url of file in guest vm:ServerFaultCode: A general system error occurred: Unknown error
2017-08-10T07:56:13.573Z - error: Error in getting fileData for nodeType. Error: ServerFaultCode: A general system error occurred: Unknown error
2017-08-10T07:56:13.573Z - error: Failed to read the nodetype, Error: A general system error occurred: Unknown error
2017-08-10T07:56:13.574Z - info: Checking if password expired
2017-08-10T07:56:14.994Z - info: Banner from server, 
VMware vCenter Server Appliance 6.0.0.30200

Type: vCenter Server with an embedded Platform Services Controller


2017-08-10T07:56:14.995Z - info: Connection ready
2017-08-10T07:56:15.008Z - info: STDOUT: Last login: Thu Aug 10 07:55:37 UTC 2017 from pc8501.domain.local on pts/0

2017-08-10T07:56:15.008Z - info: STDOUT: Last login: Thu Aug 10 07:56:15 2017 from pc8766.domain.local

2017-08-10T07:56:15.010Z - info: STDOUT: date
exit

2017-08-10T07:56:15.246Z - info: STDOUT: Connected to service

2017-08-10T07:56:15.255Z - info: STDOUT: [?1034h
    * List APIs: "help api list"
    * List Plugins: "help pi list"
    * Enable BASH access: "shell.set --enabled True"
    * Launch BASH: "shell"


2017-08-10T07:56:15.255Z - info: STDOUT: Command> d
2017-08-10T07:56:15.256Z - info: STDOUT: ate

2017-08-10T07:56:15.270Z - info: STDOUT: Unknown command: `date'
Command> exit

2017-08-10T07:56:15.305Z - info: Stream :: close
2017-08-10T07:56:15.306Z - info: Password not expired
2017-08-10T07:56:15.308Z - error: sourcePrecheck: error in getting source Info: ServerFaultCode: A general system error occurred: Unknown error

In order to address the issue you need to change the default shell for the root user. It’s very easy to do, but will also require a password change.

Logon to the current VCSA using ssh as the root user. Enable the BASH shell and start the shell using:

shell.set --enabled True
shell

Now change the root users default shell using

# chsh -s /bin/bash root

Now the installer should at least proceed through that part to deploy the image to the specified server.

References: https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2100508

Windows Update KB4034681 (August Monthly Rollup) — August 9, 2017

Windows Update KB4034681 (August Monthly Rollup)

Four hours of swearing at servers, kicking switches and rebooting printers and terminals and all because of a Windows Update.

Our entire network uses 802.1X authentication with certificates and this morning I arrived in the office to find all the Teradici terminals and network printers were failing to authenticate properly.

We hadn’t changed anything in the NPS policies so has a certificate expired? The errors in the event logs were constant

Event ID 36887 – A fatal alert was received from the remote endpoint. The TLS protocol defined fatal alert code is 42.

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OpenSSL and Subject Alternative Names — July 27, 2017

OpenSSL and Subject Alternative Names

Now that Google chrome has started bitching about certificates not having Subject Alternative Names because the practice of using Common Names in certificates has changed.

So in order to get the SAN into a CSR you need to edit the OpenSSL config file you’re using for the request. You can spend time scripting something, but for the few times I do it I’ll just copy the base openssl.cnf file to one specific to the CSR I need to create. After all you’ll already have customised the req_distinguished_name section so you don’t have to put in the country and company name all the time. eg.

$ cp /etc/ssl/openssl.cnf ~/myserver.cnf

Then I just use that new cnf file as part of the command line to create the CSR.

$ openssl req -out myserver.csr -new -newkey rsa:2048 -nodes -keyout myserver.key -config ~/myserver.cnf

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Squid Kerberos Nightmare — July 25, 2017

Squid Kerberos Nightmare

What a terrible sequence of events we suffered today. Took quite a bit of head scratching, log reading and plenty of Google fu to resolve.

We use Squid with an LDAP and authenticated lookup to establish if a user is a member of an AD group to allow them through the proxy. For some very strange reason the authentication and lookup began failing today.

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Remmina/xfreerdp Certificate Name Mismatch — July 21, 2017

Remmina/xfreerdp Certificate Name Mismatch

When using Remmina to connect to some of our older Windows systems we’re seeing a certificate problem that prevents it from connecting. Remmina pretty much says you can’t connect, but you can see the error message if you run remmina from a terminal and try to connect.

connected to server:3389
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@           WARNING: CERTIFICATE NAME MISMATCH!           @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
The hostname used for this connection (m3app) does not match any of the names given in the certificate:
Common Name (CN): no CN found in certificate
A valid certificate for the wrong name should NOT be trusted!
tls_connect: certificate not trusted, aborting.
Error: protocol security negotiation or connection failure

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Netsh Commands for NPS — April 3, 2017
CVE – Security Vunerability Datasource — March 18, 2017
STIG — March 17, 2017
Oracle Database Patches —
Guidelines for Microsoft Clustering on vSphere — March 9, 2017

Guidelines for Microsoft Clustering on vSphere

This article provides links to a subset of articles that provide guidelines and support status for running various Microsoft clustering solutions and configurations on VMware vSphere.

VMware provides customers additional flexibility and choice in architecting high-availability solutions. Microsoft has clear support statements for its clustering solutions on VMware.

Additionally, VMware provides guidelines in terms of storage protocols and number of nodes supported by VMware on vSphere, particularly for specific clustering solutions that access shared storage. Other clustering solutions that do not access shared storage, such as Exchange Cluster Continuous Replication (CCR) and Database Availability Group (DAG), can be implemented on VMware vSphere just like on physical systems without any additional considerations.

https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1037959