The NSA has published an advisory outlining how “malicious cyber actors” are “are manipulating trust in federated authentication environments to access protected data in the cloud.” This is related to the SolarWinds hack I have previously written about, and represents one of the techniques the SVR is using once it has gained access to target networks.
From the summary:
Malicious cyberactors are abusing trust in federated authentication environments to access protected data. The exploitation occurs after the actors have gained initial access to a victim’s on-premises network. The actors leverage privileged access in the on-premises environment to subvert the mechanisms that the organization uses to grant access to cloud and on-premises resources and/or to compromise administrator credentials with the ability to manage cloud resources. The actors demonstrate two sets of tactics, techniques,and procedures (TTP) for gaining access to the victim network’s cloud resources, often with a particular focus on organizational email.
In the first TTP, the actors compromise on-premises components of a federated SSO infrastructure and steal the credential or private key that is used to sign Security Assertion Markup Language (SAML) tokens(TA0006, T1552, T1552.004). Using the private keys, the actors then forge trusted authentication tokens to access cloud resources. A recent NSA Cybersecurity Advisory warned of actors exploiting a vulnerability in VMware Access and VMware Identity Manager that allowed them to perform this TTP and abuse federated SSO infrastructure.While that example of this TTP may have previously been attributed to nation-state actors, a wealth of actors could be leveraging this TTP for their objectives. This SAML forgery technique has been known and used by cyber actors since at least 2017.
In a variation of the first TTP, if the malicious cyber actors are unable to obtain anon-premises signing key, they would attempt to gain sufficient administrative privileges within the cloud tenant to add a malicious certificate trust relationship for forging SAML tokens.
In the second TTP, the actors leverage a compromised global administrator account to assign credentials to cloud application service principals (identities for cloud applications that allow the applications to be invoked to access other cloud resources). The actors then invoke the application’s credentials for automated access to cloud resources (often email in particular) that would otherwise be difficult for the actors to access or would more easily be noticed as suspicious (T1114, T1114.002).
This is an ongoing story, and I expect to see a lot more about TTP — nice acronym there — in coming weeks.
Related: Tom Bossert has a scathing op-ed on the breach. Jack Goldsmith’s essay is worth reading. So is Nick Weaver’s.