Agents are initially authenticated via Kerberos, or Certificates.  Then that 
same protocol is used for encryption of the channel - per:

https://technet.microsoft.com/en-us/library/bb735408.aspx

>From the agent to the gateway server, the Kerberos security package is used to 
>encrypt the data, because the gateway server and the agent are in the same 
>domain. The alert is decrypted by the gateway server and re-encrypted using 
>certificates for the management server. After the management server receives 
>the alert, the management server decrypts the message, re-encrypts it using 
>the Kerberos protocol, and sends it to the RMS where the RMS decrypts the 
>alert.

Some communication between the RMS and the agent may include credential 
information; for example, configuration data and tasks. The data channel 
between the agent and the management server adds another layer of encryption in 
addition to the normal channel encryption. No user intervention is required.

So - the "normal" channel is encrypted via the same process used for mutual 
authentication.  The "other" layer mentioned above is for runas account 
decryption - which is detailed below:


Then - there is another dynamic certificate key exchange used to encrypt some 
of the traffic.  You can see this certificate under the certificates view of 
the computer account of every agent or MS - in the "Operations Manager" folder:

[cid:[email protected]]


This cert has nothing to do with authentication - it is used for 
encryption/decryption of the config file for runas account distribution in 
config.  It is totally dynamic and the cert gets regenerated when necessary 
automatically.  If you delete it - it will regenerate on the next health 
service restart.

You will see this event in the log:

Log Name:      Operations Manager
Source:        HealthService
Date:          12/3/2015 8:23:12 AM
Event ID:      7006
Task Category: Health Service
Level:         Information
Keywords:      Classic
User:          N/A
Computer:      WINS2012R2.dmz.corp
Description:
The Health Service has published the public key [4A A8 71 8B 0D 3F 9E 9D 4A 59 
44 D8 EE BC B1 42 ] used to send it secure messages to management group OMMG1.  
 This message only indicates that the key is scheduled for delivery, not that 
delivery has been confirmed.

The thumbprint of this message matches the cert in that location.

The certificate is solely used to protect RunAs account credentials in the 
transmission from the management server to the agent.  It doesn't have any 
impact on how they are stored on the agent itself, and is not used for 
authentication.  On the agent RunAs accounts are stored in the registry and 
protected using DPAPI.  RunAs accounts are sent to the agent as part of the 
OpsMgrConnector.Config.xml file.  In that file the RunAs accounts are 
encrypted, base64 encoded and placed in the Message/State/SecureData element.  
The encryption key is the agent self-signed certificate.  When the agent starts 
up it creates or gets the existing certificate and publishes the public key to 
its management server, which then submits it to the database via the SDK 
service.  When the configuration service generates configuration for an agent, 
it looks up the public key for that agent, and then uses that key to encrypt 
the SecureData part of the configuration XML.  The agent has a cert lifetime 
set of 1 year and will generate and transmit a new certificate when it is 
getting near expiration.





From: [email protected] [mailto:[email protected]] On 
Behalf Of Pete Hakesley
Sent: Thursday, December 3, 2015 5:24 AM
To: MSMOM ([email protected]) <[email protected]>
Subject: [msmom] Agent to MS Traffic Encyption

Hi all,

Had an interesting question yesterday. We know the requirement for certificates 
and that the agent initiates the comms to the GW/MS for attack vector reasons 
etc.

But the question is the data between the agent and the GW/MS encrypted in any 
way.
We are bidding for a contract for a financial organisation [SCOM2012 R2 
multi-Tenant] and they need to know - Microsoft literature eludes to yes but I 
cannot find a definitive statement.

Can anyone help?


Peter Hakesley | Monitoring & Automation Technical Lead Engineer, Data Centre 
Services

t: +44(0)845 155 6556 ext: 4006
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