Survivable Branch Appliances are a pretty common device in multi-site companies that need local breakout for calls or need to have the ability to make calls when the connection to the Front End pool of Skype for Business servers is unavailable (WAN outage, etc).
In patching of these this question comes up at least every 3 months:
“I’ve applied all the Windows Updates that Sonus say my SBA needs however it’s still showing as needing updates in WSUS”
“We’ve had a vulnerability scan and loads of updates are missing from all of our SBAs”
So what gives?
This comes down to past decisions from Microsoft and Sonus…..
In the dim and distant Microsoft used to release multiple updates every Patch Tuesday. You could choose if you wanted to install update X for GDI+ but not update Y for TrueType fonts. That meant that other software companies could say:
“Yea – we found an issue with Contoso Magic Application and KB938464 so if you want to use our software to do your business critical function don’t install that update…..
……honest – we’ll release an update to fix this in our application at some point”
And you as an administrator would be told from the business that you can’t install that update as they need Contoso Magic Application to just work.
So how does this relate to SBA’s
Each month Sonus looked at the updates available and then at the profile of the SBA with the Sonus hardened config on there and said:
“okay, so update X and Y we need, but update Z is for part of Windows that is not exposed to the network with our hardening so therefore no need to install it”
Thus inside the PKG file you download from Sonus you have a list of updates that are allowed and only those would get installed.
Then things changed
Microsoft got bored of having to support a Swiss Cheese deployment of Windows so they started in October 2016 to release single monthly updates for OS. I believe that this is in part to do with this statistic I picked up from Henk van Roest who stated “30% of support calls to Microsoft are fixed by applying updates that are already available”. You could no longer pick and choose which updates to install, you either installed this months updates or you didn’t.
However Sonus still release an update each month that contains this update. However they have not gone back and subsequently authorised the updates that came out prior to October 2016.
Where does this leave you as an Administrator?
The reason for applying updates from the Sonus PKG file is to ensure that the SBA stays in Appliance Mode. Appliance Mode means that the SBA call paths are supported by Sonus. However – you will not be able to install all Windows Updates that a offered from WSUS and thus may fall down on an audit. So, you have a choice:
- Stay in Appliance Mode - only apply PKG files from Sonus
- Apply all updates - keep off those audit reports
The choice is yours!