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العربيةTake over an OIDC provider to assume trusting roles
Can re-point the OIDC provider a role trusts, forging federated logins as it.
Grants escalation on its own.
iam:UpdateOpenIDConnectProviderThumbprintOn its own, iam:UpdateOpenIDConnectProviderThumbprint can re-point the OIDC provider a role trusts, forging federated logins as it. On a wide resource scope that alone reaches a standing way back in.
Why it is dangerous
A principal can call iam:UpdateOpenIDConnectProviderThumbprint to change the trusted thumbprint of the OIDC the provider trusts (or add a client ID), making tokens from an attacker-controlled IdP valid. It then calls sts:AssumeRoleWithWebIdentity to assume the target role directly - authorised by the target role's trust policy, not by any identity permission. If the target role is privileged this is a full federation takeover.
In MITRE ATT&CK terms this maps to T1556, Modify Authentication Process, under the persistence tactic. AWS records it in CloudTrail as UpdateOpenIDConnectProviderThumbprint, AddClientIDToOpenIDConnectProvider. The call shows up in CloudTrail but blends into normal administration, so it needs a rule to stand out. It also gives an attacker a way to keep access after the first foothold is closed, so it is worth watching even when it looks like routine administration.
Detection
UpdateOpenIDConnectProviderThumbprintAddClientIDToOpenIDConnectProviderPrerequisites
iam:UpdateOpenIDConnectProviderThumbprint on an OIDC provider that at least one role trusts (same account). No identity permission is needed for the subsequent AssumeRoleWithWebIdentity - the role's trust authorises it.
MITRE ATT&CK
T1556 · Modify Authentication ProcessTactic
Persistence
A control that would remove it: Restrict iam:UpdateOpenIDConnectProviderThumbprint / iam:AddClientIDToOpenIDConnectProvider to break-glass admins; alarm on them (CloudTrail); pin role trust to specific sub/aud claims.
Whether to apply it depends on how the permission is used in your environment, so it is a business decision rather than an automatic fix. The same permission can be load-bearing in one account and pure risk in another.
Pathbreak confirms whether this path resolves in your account, ranks it against the others by how much it opens up, and uses your threat model and business context to show which paths are worth cutting.
Questions
What does iam:UpdateOpenIDConnectProviderThumbprint allow?
Can re-point the OIDC provider a role trusts, forging federated logins as it.
Can iam:UpdateOpenIDConnectProviderThumbprint escalate privileges on its own?
Yes. Held on a broad enough resource it reaches a standing way back in with no other permission.
How is take over an OIDC provider to assume trusting roles detected?
Watch for UpdateOpenIDConnectProviderThumbprint, AddClientIDToOpenIDConnectProvider in CloudTrail. The call shows up in CloudTrail but blends into normal administration, so it needs a rule to stand out.
How do you break this path?
A control that would remove it is: Restrict iam:UpdateOpenIDConnectProviderThumbprint / iam:AddClientIDToOpenIDConnectProvider to break-glass admins; alarm on them (CloudTrail); pin role trust to specific sub/aud claims. Whether to apply it depends on how the permission is used in your account, so it is a business decision rather than an automatic fix.
Which MITRE ATT&CK technique is this?
T1556, Modify Authentication Process, under the persistence tactic.
Related paths
References
- https://attack.mitre.org/techniques/T1556/
- https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_providers_oidc.html
Find this in your own account
We run a read-only scan of one AWS account and show you which of these paths exist, ranked by blast radius, with the change that breaks each one. First validated paths within the hour.