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العربيةHijack EC2 user-data
Can rewrite an instance's user-data and run code as its instance-profile role.
Grants escalation only in combination. All of these are needed together:
ec2:ModifyInstanceAttributeec2:StartInstancesec2:StopInstancesec2:ModifyInstanceAttribute can rewrite an instance's user-data and run code as its instance-profile role, but only when it is held together with ec2:StartInstances, ec2:StopInstances. Held together they reach administrator access.
Why it is dangerous
A principal can stop the instance, rewrite its user-data with ec2:ModifyInstanceAttribute, and start it again; on boot the instance runs the attacker's user-data script as its already-attached instance-profile role, no iam:PassRole needed. A privileged instance profile means arbitrary code execution as that role: full privilege escalation against a box that was already trusted.
In MITRE ATT&CK terms this maps to T1578, Modify Cloud Compute Infrastructure, under the privilege escalation tactic. AWS records it in CloudTrail as ModifyInstanceAttribute, StopInstances, StartInstances. The call is loud in CloudTrail and stands out from normal activity.
Detection
ModifyInstanceAttributeStopInstancesStartInstancesPrerequisites
An existing instance with an instance profile; permission to stop/modify/start it.
MITRE ATT&CK
T1578 · Modify Cloud Compute InfrastructureTactic
Privilege Escalation
A control that would remove it: Restrict ec2:ModifyInstanceAttribute on instances with attached instance profiles.
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 ec2:ModifyInstanceAttribute allow?
Can rewrite an instance's user-data and run code as its instance-profile role.
What else is needed for ec2:ModifyInstanceAttribute to be dangerous?
It becomes an escalation only when held together with ec2:StartInstances, ec2:StopInstances. On its own it is not enough, which is what makes the combination easy to miss.
How is hijack EC2 user-data detected?
Watch for ModifyInstanceAttribute, StopInstances, StartInstances 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: Restrict ec2:ModifyInstanceAttribute on instances with attached instance profiles. 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?
T1578, Modify Cloud Compute Infrastructure, under the privilege escalation tactic.
Related paths
References
Find this in your own account
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