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العربيةSelf-grant KMS decrypt via key policy
Can rewrite a KMS key's policy to grant itself decrypt, then decrypt with it.
Grants escalation on its own.
kms:PutKeyPolicyOn its own, kms:PutKeyPolicy can rewrite a KMS key's policy to grant itself decrypt, then decrypt with it. On a wide resource scope that alone reaches access for an outside or public principal.
Why it is dangerous
A principal can call kms:PutKeyPolicy on the key to attach a key-policy statement granting itself kms:Decrypt, then decrypt the ciphertext the key protects. The key is a gatekeeper: decrypt access unlocks every secret, volume, snapshot and object the key gates, so rewriting the key's own policy amplifies into control of all the data it protects.
In MITRE ATT&CK terms this maps to T1098, Account Manipulation, under the privilege escalation tactic. AWS records it in CloudTrail as PutKeyPolicy, CreateGrant. The call shows up in CloudTrail but blends into normal administration, so it needs a rule to stand out.
Detection
PutKeyPolicyCreateGrantPrerequisites
kms:PutKeyPolicy on the customer-managed key (or kms:CreateGrant). The abuse assumes no SCP/boundary/PrincipalOrgID guardrail blocks the over-grant; possession of (or access to) the ciphertext is needed to use the unlocked decrypt.
MITRE ATT&CK
T1098 · Account ManipulationTactic
Privilege Escalation
A control that would remove it: Restrict kms:PutKeyPolicy and kms:CreateGrant to key admins; keep the default key policy's self-management guard; deny key-policy writes via SCP.
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:PutKeyPolicy allow?
Can rewrite a KMS key's policy to grant itself decrypt, then decrypt with it.
Can kms:PutKeyPolicy 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 key policy detected?
Watch for PutKeyPolicy, CreateGrant in CloudTrail. The call shows up in CloudTrail but blends into normal administration, so it needs a rule to stand out.
How do you break this path?
A control that would remove it is: Restrict kms:PutKeyPolicy and kms:CreateGrant to key admins; keep the default key policy's self-management guard; deny key-policy writes via SCP. 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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