I guess the entire SharePoint world now is aware of the post SP1 "Infrastructure updates" put out by Microsoft recently. Probably the best thing about them are that the flaky "content deployment" feature has had some serious work done on it. (My advice has always been use with extreme caution or avoid it, but now I will have to reassess).
Anyway, that is not what I am writing about. Being a former IT Security consultant, I have always installed SharePoint in a "least privilege" configuration. I use different service accounts for search, farm, SSP, reporting services and web applications. The farm account in particular, is one that needs to be very carefully managed given its control over the heart of SharePoint – the configuration database.
Specifically, the farm account never should have any significant rights on any SharePoint farm server, over and above what it minimally needs (which is some SQL Server rights and some DCOM permission stuff). For what it’s worth, I do not use the Network Service account either, as it is actually more risky than a low privileged domain or local user account.
Developers on the other hand tend to run their boxes as full admin. I have no problem with this, so long as there is a QA or test server that is running least privilege.
However, as always with tightening the screws, there are some potential side effects in doing this. There are occasions when the farm account actually needs to perform a task that requires higher privileges, over and above what it has by default. Upgrading SharePoint from a standard to enterprise license is one such example, and it seems that performing the infrastructure update may be another.
If you take the time to read the installation instructions for the infrastructure update, there is this gem of advice:
To ensure that you have the correct permissions to install the software update and run the SharePoint Products and Technologies Configuration Wizard, we recommend that you add the account for the SharePoint Central Administration v3 application pool identity to the Administrators group on each of the local Web servers and application servers and then log on by using that account
You may wonder why this even matters? After all, it is exceedingly likely that you logged into the server as an administrator or domain administrator anyway. Surely you have all the permission that you need, right?
The answer is that not all update tasks are run by your logged-in account. Although you start the installation using your account, at a certain point during the install, many tasks are performed by the SharePoint Central Administration application. Thus, despite you having administrative permissions, SharePoint (using the farm account) will not have.
So the advice above essentially says, temporarily add the SharePoint farm account to the local administrators group and then log into the server as that user account. Now perform the action as instructed. That way the account that starts the installation is the same account that runs SharePoint and thus we know that we are using the correct account with the correct server privileges.
Once the installation has been completed, you can log out of the farm account and then revoke its administrator access, and we are back to the original locked down configuration.
So keep this in mind when performing farm tasks that are likely to require some privileges at the operating system level. It is a good habit to get into (provided you remember to lock down permissions afterwards 🙂 ).