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العربيةPass role to ECS task on EC2
Can start an ECS task on EC2 with a role and run a container as it.
Grants escalation only in combination. All of these are needed together:
iam:PassRoleecs:RegisterTaskDefinitionecs:StartTaskiam:PassRole can start an ECS task on EC2 with a role and run a container as it, but only when it is held together with ecs:RegisterTaskDefinition, ecs:StartTask. Held together they reach administrator access.
Why it is dangerous
A principal holds iam:PassRole on the target role plus ecs:RegisterTaskDefinition and ecs:StartTask, so it can register a task definition using an attacker-controlled container image with the target role as the task role and start it on an existing EC2 container instance, the container then executes with the target role's permissions and can read the target role's credentials from the task-metadata endpoint. Because the target role trusts ecs-tasks.amazonaws.com the pass is accepted; the privileged role yields run-as-role code execution.
In MITRE ATT&CK terms this maps to T1610, Deploy Container, under the privilege escalation tactic. AWS records it in CloudTrail as RegisterTaskDefinition, StartTask. The call is loud in CloudTrail and stands out from normal activity.
Detection
RegisterTaskDefinitionStartTaskPrerequisites
Target role's trust policy must allow ecs-tasks.amazonaws.com; an EC2 container instance in the cluster to start the task on.
MITRE ATT&CK
T1610 · Deploy ContainerTactic
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 start an ECS task on EC2 with a role and run a container as it.
What else is needed for iam:PassRole to be dangerous?
It becomes an escalation only when held together with ecs:RegisterTaskDefinition, ecs:StartTask. On its own it is not enough, which is what makes the combination easy to miss.
How is pass role to ECS task on EC2 detected?
Watch for RegisterTaskDefinition, StartTask 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?
T1610, Deploy Container, 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.