OIDC tokens can now restrict which AWS roles they assume

by Aidan Steele

Aidan (self-proclaimed squirrel on meth) went digging into a barely-documented new STS condition key, sts:RoleAuthorizedByIdp, and reverse-engineered how it actually works. An OIDC token can now carry a https://aws.amazon.com/roles claim listing one or more role ARNs it is permitted to assume, and AssumeRoleWithWebIdentity checks that allow-list before it even looks at the role's trust policy. Put role X's ARN in the token, ask for role Y, and STS rejects you with InvalidIdentityToken regardless of what Y's trust policy allows. It's near-useless today unless you run your own IdP (matches must be literal ARNs, no wildcards, and CloudTrail only logs the field when it's present), but it hands identity providers a real veto over role selection that a misconfigured trust policy can't undo.

Introducing ClickOps Sentinel: AI Context for AWS Console Changes

by Victor Grenu

Even in shops that live by IaC, someone eventually opens the console and clicks stuff. Victor's open-source ClickOps Sentinel catches those moments off the CloudTrail sessionCredentialFromConsole flag, which AWS sets server-side for every console-session API call. Each triggered detection is handed to a Claude agent on Bedrock that retraces the whole console session via LookupEvents, checks adjacent activity from the same IP, and emits a reasoned verdict (manual-change-confirmed / likely-sanctioned-activity / suspicious) with security and FinOps implications. I'm not sure how good this will be in a large environment but seems better than another "someone changed a security group" ping.

Investigating Persistence Mechanisms in AWS

by Jan Blažek

Jan walks the four persistence techniques that can survive long after you think an incident is closed. 1. backdoor IAM users, 2. iam:UpdateAssumeRolePolicy to whitelist an external account, 3. malicious Lambda code, and 4. sts:GetFederationToken sessions. He pairs each with queries (over ingested CloudTrail data, not native CloudTrail) to hunt them, including pivoting from a federated session back to the source IAM user. It's a reference guide rather than novel research, but it's a clean, AWS-native investigation playbook worth keeping around.

Bonus: Filtering S3 events by CloudFormation stack

by Aidan Steele