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العربيةHijack Lambda function code
Can overwrite a function's code and run it as its execution role.
Grants escalation on its own.
lambda:UpdateFunctionCodeOn its own, lambda:UpdateFunctionCode can overwrite a function's code and run it as its execution role. On a wide resource scope that alone reaches administrator access.
Why it is dangerous
A principal can call lambda:UpdateFunctionCode on an existing function that runs as the function, overwriting the function's deployment package with attacker-controlled code. On the next invocation that code executes with the function's permissions and reads the function's live credentials from the Lambda runtime environment, no iam:PassRole needed, because the function is already bound to the function. If the function is privileged this is full privilege escalation against a function 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 UpdateFunctionCode20150331v2, UpdateFunctionCode. The call is loud in CloudTrail and stands out from normal activity.
Detection
UpdateFunctionCode20150331v2UpdateFunctionCodePrerequisites
An existing Lambda function with an execution role; permission to update its code. Execution happens on the next trigger (or an invocation the attacker can cause), no separate invoke permission is required for the role-credential theft itself.
MITRE ATT&CK
T1578 · Modify Cloud Compute InfrastructureTactic
Privilege Escalation
A control that would remove it: Restrict lambda:UpdateFunctionCode to CI/CD principals; reduce the function execution role's permissions.
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 lambda:UpdateFunctionCode allow?
Can overwrite a function's code and run it as its execution role.
Can lambda:UpdateFunctionCode escalate privileges on its own?
Yes. Held on a broad enough resource it reaches administrator access with no other permission.
How is hijack Lambda function code detected?
Watch for UpdateFunctionCode20150331v2, UpdateFunctionCode 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 lambda:UpdateFunctionCode to CI/CD principals; reduce the function execution role's permissions. 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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