>In the immediate aftermath of the attack, Microsoft advised customers of Microsoft 365 to disable seamless SSO in AD FS and similar products — the solution that Harris proposed three years earlier.
And did Microsoft advise those other solutions prior to Solarwinds happening?
What it says is "be careful when using federated trust relationships, because if one of your trusted environments is pwned, it will be trusted by the others". That's very obvious.
And about "disable seamless SSO", I only found this: "On-premises SSO systems: Deprecate any on-premises federation and Web Access Management infrastructure and configure applications to use Azure AD." (Seems pretty basic too, especially considering how vulnerable on-prem ADs are).
The original article seems to paint this MS page as a security advisory or vulnerability notification, while it just seems to me to be a very very basic security guideline.
Maybe Andrew being overly cautious, was assuming most government users didn't know these basic facts, and should be warned anyway? Was MS pushing back on his report because communicating something like this to users would probably sow too much confusion?
That would still a failure on MS's part, but would make for a much more boring story. The article makes it seem like Andrew discovered an atomic bomb and MS pushed it under the rug. The reality seems much more bland.
But still, could you elaborate on the default configuration being insecure? I know next to nothing about Azure/Entra, maybe I'm missing something important.
According to the article, that's not the reason Microsoft gave for not advising it. The reasons they gave were (1) it would make governments scared and jeopardize contracts and (2) it would let hackers know about the attack.
Also according to the article, the NYPD weren't aware of the problem until Harris warned them of it, then they quickly disabled seamless SSO:
>On a visit to the NYPD, Harris told a top IT official, Matthew Fraser, about the AD FS weakness and recommended disabling seamless SSO. Fraser was in disbelief at the severity of the issue, Harris recalled, and he agreed to disable seamless SSO.
>In an interview, Fraser confirmed the meeting.
>“This was identified as one of those areas that was prime, ripe,” Fraser said of the SAML weakness. “From there, we figured out what’s the best path to insulate and secure.”
>But still, could you elaborate on the default configuration being insecure? I know next to nothing about Azure/Entra, maybe I'm missing something important.
I'm not very familiar with Azure either. I'm getting most of this from the article. It sounds like the weakness is that by default trust federation to Microsoft 365 is enabled. Microsoft's post-Solarwinds article recommends disabling it.
You have to steal the private key for the SAML signing certificate for an app. The correct answer would be to scope any token to only have access to what the app has access to, the second layer which is documented in their 2020 article, is to require mfa on admin actions, and the 3rd layer is to disconnect azure admin accounts from on-prem admin accounts preventing this type of attack.
But disabling SSO altogether is non-starter for most businesses, what are we going to do tomorrow? Spend months recreating 100,000x accounts in various applications, no.
We decrypt ssl traffic in our company, someone steals the private key and now can read the entire stream including your bank account details, lets stop decrypting ssl traffic because someone might leak the key? The answer from the infosec communinity has been its worth the risk.