AWS DVA-C02 Drill: IAM Permissions - Least Privilege for CodeCommit Branch Management

Jeff’s Note

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Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Lead Developer.

For DVA-C02 candidates, the confusion often lies in selecting precise IAM actions that enable necessary operations—but nothing more. In production, this is about knowing exactly which IAM permissions map to Git operations, particularly branch management over SSH for CodeCommit repositories. Let’s drill down.

The Certification Drill (Simulated Question)

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Scenario

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Your team at Nebula Apps develops software that uses AWS CodeCommit as the source control repository. Developers access their repositories via SSH authentication tied to IAM users. One developer on the team needs to be granted permission to create and delete branches in a specific CodeCommit repository, adhering strictly to the Principle of Least Privilege.

The Requirement:

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Identify which specific IAM permissions allow this developer to create and delete branches in CodeCommit without over-privileging.

The Options

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• A) “codecommit:CreateBranch” and “codecommit:DeleteBranch”
• B) “codecommit:Put*”
• C) “codecommit:Update*”
• D) “codecommit:*”

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leave a comment:

Correct Answer

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A

Quick Insight: The Developer Imperative

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To strictly follow least privilege, assign only the specific branch management permissions (CreateBranch and DeleteBranch) rather than wildcard permissions like Put* or Update*, which grant broader, unnecessary capabilities.

Content Locked: The Expert Analysis

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You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?

The Expert’s Analysis

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Correct Answer

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Option A

The Winning Logic

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Creating and deleting branches in AWS CodeCommit require the IAM actions codecommit:CreateBranch and codecommit:DeleteBranch. These are fine-grained permissions scoped to just branch management.

• Permissions with wildcards like codecommit:Put* or codecommit:Update* include many other actions unrelated to branch management such as PutFile or UpdateDefaultBranch, over-privileging the developer.
• Granting codecommit:* (full permission) grants unnecessary broad access, violating least privilege principles and risked exposing other sensitive operations like repository deletion or settings changes.

By granting only codecommit:CreateBranch and codecommit:DeleteBranch, you tightly control branch operations without opening up the repository to more actions than necessary—ideal for a developer who only needs branch control.

The Trap (Distractor Analysis):

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• Why not B (“codecommit:Put”)?*
  This includes write actions beyond branches, such as putting files and uploading content, which are unrelated and may lead to excessive privileges.

• Why not C (“codecommit:Update”)?*
  This covers updating repository details and configurations but does not explicitly allow branch creation or deletion, so it’s incomplete.

• Why not D (“codecommit:*”)?
  Fully permissive — violates principle of least privilege and increases risk surface unnecessarily.

The Technical Blueprint

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{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "codecommit:CreateBranch",
        "codecommit:DeleteBranch"
      ],
      "Resource": "arn:aws:codecommit:us-east-1:123456789012:YourRepoName"
    }
  ]
}

The Comparative Analysis

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Real-World Application (Practitioner Insight)

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Exam Rule

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For the exam, always pick the narrowly scoped permissions when you see branch operations in CodeCommit.

Real World

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In practice, teams might bundle multiple permissions if developers have varied repo access needs. But in compliance-sensitive environments, granular control (like only CreateBranch/DeleteBranch) is critical to reduce attack surface.

(CTA) Stop Guessing, Start Mastering

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Disclaimer

This is a study note based on simulated scenarios for the AWS DVA-C02 exam.