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العربيةPass role to ECS task (StartTask override)
Can start an ECS task with a role via taskRoleArn override and run a container as it.
Grants escalation only in combination. All of these are needed together:
iam:PassRoleecs:StartTaskiam:PassRole can start an ECS task with a role via taskRoleArn override and run a container as it, but only when it is held together with ecs:StartTask. Held together they reach administrator access.
Why it is dangerous
A principal holds iam:PassRole on the target role plus ecs:StartTask, so it can start an existing ECS task definition on an EC2 container instance with overrides.taskRoleArn set to the target role and an attacker container command, no ecs:RegisterTaskDefinition needed. The task executes the command with the target role's permissions and reads the target role's credentials from the task-metadata endpoint. Because the target role trusts ecs-tasks.amazonaws.com the pass is accepted; if the target role is privileged this is full privilege escalation.
In MITRE ATT&CK terms this maps to T1610, Deploy Container, under the privilege escalation tactic. AWS records it in CloudTrail as StartTask. The call is loud in CloudTrail and stands out from normal activity.
Detection
StartTaskPrerequisites
Target role's trust policy must allow ecs-tasks.amazonaws.com; an existing task definition and a registered EC2 container instance in the cluster. Command + taskRoleArn overrides must be permitted (the default).
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; deny taskRoleArn/command overrides on StartTask.
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 with a role via taskRoleArn override 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:StartTask. On its own it is not enough, which is what makes the combination easy to miss.
How is pass role to ECS task (StartTask override) detected?
Watch for 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; deny taskRoleArn/command overrides on StartTask. 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
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