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العربيةSelf-grant KMS Decrypt via grant
Can grant itself Decrypt on a KMS key via a grant.
Grants escalation on its own.
kms:CreateGrantOn its own, kms:CreateGrant can grant itself Decrypt on a KMS key via a grant. On a wide resource scope that alone reaches access for an outside or public principal.
Why it is dangerous
A principal can call kms:CreateGrant on the key to grant itself (or an attacker principal) Decrypt, bypassing the key policy entirely. This is disproportionately valuable because it manufactures the kms:Decrypt half of every KMS-gated data path (S3-SSE, Secrets Manager CMK, encrypted snapshots).
In MITRE ATT&CK terms this maps to T1098, Account Manipulation, under the privilege escalation tactic. AWS records it in CloudTrail as CreateGrant. The call is quiet against normal activity, so it is easy to miss without a rule for it. It also gives an attacker a way to keep access after the first foothold is closed, so it is worth watching even when it looks like routine administration.
Detection
CreateGrantPrerequisites
kms:CreateGrant on the key.
MITRE ATT&CK
T1098 · Account ManipulationTactic
Privilege Escalation
A control that would remove it: Restrict kms:CreateGrant on the key; a grant is a separate authz channel from the key policy and must be controlled independently.
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 kms:CreateGrant allow?
Can grant itself Decrypt on a KMS key via a grant.
Can kms:CreateGrant escalate privileges on its own?
Yes. Held on a broad enough resource it reaches access for an outside or public principal with no other permission.
How is self-grant KMS Decrypt via grant detected?
Watch for CreateGrant in CloudTrail. The call is quiet against normal activity, so it is easy to miss without a rule for it.
How do you break this path?
A control that would remove it is: Restrict kms:CreateGrant on the key; a grant is a separate authz channel from the key policy and must be controlled independently. 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?
T1098, Account Manipulation, under the privilege escalation tactic.
Related paths
References
Find this in your own account
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