The correct answer is A. Revoke all versions of the signing profile assigned to the developer.

According to the AWS documentation1, AWS Signer is a fully managed code-signing service that helps you ensure the trust and integrity of your code. You can use Signer to sign code artifacts, such as Lambda deployment packages, with code-signing certificates that you control and manage.

A signing profile is a collection of settings that Signer uses to sign your code artifacts. A signing profile includes information such as the following:

The type of signature that you want to create (for example, a code-signing signature).

The signing algorithm that you want Signer to use to sign your code.

The code-signing certificate and its private key that you want Signer to use to sign your code.

You can create multiple versions of a signing profile, each with a different code-signing certificate. You can also revoke a version of a signing profile if you no longer want to use it for signing code artifacts.

In this case, the company wants to ensure that all the code that the developer wrote can no longer be deployed to the Lambda functions. One way to achieve this is to revoke all versions of the signing profile that was assigned to the developer. This will prevent Signer from using that signing profile to sign any new code artifacts, and also invalidate any existing signatures that were created with that signing profile. This way, the company can ensure that only trusted and authorized code can be deployed to the Lambda functions.

The other options are incorrect because:

B. Examining the developer’s IAM roles and removing all permissions that grant access to Signer may not be sufficient to prevent the deployment of the developer’s code. The developer may have already signed some code artifacts with a valid signing profile before leaving the company, and those signatures may still be accepted by Lambda unless the signing profile is revoked.

C. Re-encrypting all source code with a new AWS Key Management Service (AWS KMS) key may not be effective or practical. AWS KMS is a service that lets you create and manage encryption keys for your data. However, Lambda does not require encryption keys for deploying code artifacts, only valid signatures from Signer. Therefore, re-encrypting the source code may not prevent the deployment of the developer’s code if it has already been signed with a valid signing profile. Moreover, re-encrypting all source code may be time-consuming and disruptive for other developers who are working on the same code base.

D. Using Amazon CodeGuru to profile all the code that the Lambda functions use may not help with preventing the deployment of the developer’s code. Amazon CodeGuru is a service that provides intelligent recommendations to improve your code quality and identify an application’s most expensive lines of code. However, CodeGuru does not perform any security checks or validations on your code artifacts, nor does it interact with Signer or Lambda in any way. Therefore, using CodeGuru may not prevent unauthorized or untrusted code from being deployed to the Lambda functions.