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العربيةPass role to CloudFormation StackSet update
Can update a CloudFormation StackSet with a role across accounts.
Grants escalation only in combination. All of these are needed together:
iam:PassRolecloudformation:UpdateStackSetiam:PassRole can update a CloudFormation StackSet with a role across accounts, but only when it is held together with cloudformation:UpdateStackSet. Held together they reach administrator access.
Why it is dangerous
A principal holds iam:PassRole on the target role plus cloudformation:UpdateStackSet, so it can update an existing StackSet with an attacker-authored template and the target role as its execution role; on rollout CloudFormation provisions every resource in the template with the target role's permissions across the StackSet's target accounts. Because the target role trusts cloudformation.amazonaws.com the pass is accepted; the privileged role lets the template create admin resources, full privilege escalation, fanned out across accounts, with no need to create a new StackSet.
In MITRE ATT&CK terms this maps to T1648, Serverless Execution, under the privilege escalation tactic. AWS records it in CloudTrail as UpdateStackSet. The call is loud in CloudTrail and stands out from normal activity.
Detection
UpdateStackSetPrerequisites
Target role's trust policy must allow cloudformation.amazonaws.com. Both cloudformation:UpdateStackSet and iam:PassRole are required; CloudFormation runs the attacker's template as the execution role, so no separate cred-theft step is needed. An existing StackSet to update is assumed.
MITRE ATT&CK
T1648 · Serverless ExecutionTactic
Privilege Escalation
A control that would remove it: Remove iam:PassRole for this role or scope it with iam:PassedToService.
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:PassRole allow?
Can update a CloudFormation StackSet with a role across accounts.
What else is needed for iam:PassRole to be dangerous?
It becomes an escalation only when held together with cloudformation:UpdateStackSet. On its own it is not enough, which is what makes the combination easy to miss.
How is pass role to CloudFormation StackSet update detected?
Watch for UpdateStackSet in CloudTrail. The call is loud in CloudTrail and stands out from normal activity.
How do you break this path?
A control that would remove it is: Remove iam:PassRole for this role or scope it with iam:PassedToService. 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?
T1648, Serverless Execution, under the privilege escalation tactic.
Related paths
References
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.