Exercise 35: Cloud Encryption Key Management Vulnerability

Objective:

Understand the risks of improper encryption key management in cloud environments. Simulate a scenario where encryption is enabled but encryption keys are mismanaged, leading to data exposure. Learn best practices for securing encryption keys and mitigating risks.

---

Scenario:

An organization enables encryption for sensitive data in cloud storage (e.g., AWS S3 or Google Cloud Storage) but mismanages encryption keys by storing them insecurely or failing to implement proper access controls. An attacker uses a compromised encryption key to access sensitive data. Your goal is to simulate this scenario, highlight its impact, and recommend secure key management practices.

---

Lab Setup:

Prerequisites:

1. Access to a cloud platform:
   • AWS (S3, KMS) or Google Cloud (Cloud Storage, Cloud KMS).
2. Installed tools:
   • aws-cli (Installation Guide).
   • gcloud CLI (Installation Guide).

---

Steps to Set Up the Lab:

1. Create a Cloud Storage Bucket with Encryption:
   • AWS S3:
     1. Create an S3 bucket with server-side encryption:bashCopyEditaws s3api create-bucket --bucket encrypted-bucket --region us-east-1 aws s3api put-bucket-encryption --bucket encrypted-bucket --server-side-encryption-configuration '{ "Rules": [ { "ApplyServerSideEncryptionByDefault": { "SSEAlgorithm": "aws:kms", "KMSMasterKeyID": "<key-id>" } } ] }'
     2. Upload a sensitive file:bashCopyEditecho "Sensitive Data" > sensitive-data.txt aws s3 cp sensitive-data.txt s3://encrypted-bucket/
   • Google Cloud Storage:
     1. Create a bucket and enable customer-managed encryption:bashCopyEditgcloud storage buckets create encrypted-bucket --location=us --encryption-key=<kms-key-id>
     2. Upload a sensitive file:bashCopyEditecho "Sensitive Data" > sensitive-data.txt gcloud storage cp sensitive-data.txt gs://encrypted-bucket/
2. Misconfigure Key Management:
   • Store the encryption key in an insecure location:
     • Save the key in plain text on a local machine:bashCopyEditecho "<kms-key-id>" > kms-key.txt
     • Ensure the file has loose permissions:bashCopyEditchmod 777 kms-key.txt
3. Grant Excessive Key Permissions:
   • AWS KMS:
     • Attach a permissive key policy to the KMS key:jsonCopyEdit{ "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Principal": "*", "Action": "kms:Decrypt", "Resource": "*" } ] }
   • Google Cloud KMS:
     • Add an overly broad IAM role to the key:bashCopyEditgcloud kms keys add-iam-policy-binding <key-name> \ --keyring=<key-ring-name> \ --location=<location> \ --member="allUsers" \ --role="roles/cloudkms.cryptoKeyDecrypter"

---

Exercise: Simulating Key Compromise and Unauthorized Access

Objective:

Simulate an attacker using a compromised encryption key to access encrypted data.

1. Enumerate Key Permissions:
   • Check the current access policy for the key:
     • AWS:bashCopyEditaws kms get-key-policy --key-id <key-id> --policy-name default
     • Google Cloud:bashCopyEditgcloud kms keys get-iam-policy <key-name> --keyring=<key-ring-name> --location=<location>
2. Use the Compromised Key:
   • AWS:
     • Simulate an attacker decrypting the encrypted data:bashCopyEditaws s3api get-object --bucket encrypted-bucket --key sensitive-data.txt sensitive-data.txt
   • Google Cloud:
     • Use the gcloud CLI to access the encrypted file:bashCopyEditgcloud storage cp gs://encrypted-bucket/sensitive-data.txt .
3. Attempt Unauthorized Access:
   • Simulate privilege escalation using the permissive key policy:
     • AWS:bashCopyEditaws kms decrypt --key-id <key-id> --ciphertext-blob <encrypted-data>
     • Google Cloud:bashCopyEditgcloud kms decrypt --key=<key-name> --keyring=<key-ring-name> --location=<location> --plaintext-file=decrypted-data.txt --ciphertext-file=encrypted-data.txt

---

Tools Required:

1. AWS KMS or Google Cloud KMS: For encryption key management.
2. S3 or Google Cloud Storage: For storing and encrypting sensitive data.
3. aws-cli or gcloud CLI: For interacting with cloud resources.

---

Deliverables:

1. Exploit Report:
   • Evidence of accessing encrypted data using compromised encryption keys.
   • Logs or screenshots showing excessive permissions or insecure key storage.
2. Recommendations:
   • Best practices for secure encryption key management.

---

Solution:

1. Identified Vulnerabilities:
   • Insecure Key Storage: The encryption key was stored in plaintext on a local machine with weak file permissions.
   • Excessive Permissions: The key policy allowed unauthorized users to decrypt data.
   • No Key Rotation: Encryption keys were not rotated, increasing the risk of key compromise.
2. Consequences:
   • Data Breach: Attackers accessed sensitive data using compromised encryption keys.
   • Regulatory Violations: Improper encryption key management violated compliance requirements (e.g., GDPR, HIPAA).
   • Operational Risks: Key compromise could lead to further unauthorized access to cloud resources.
3. Prevention Techniques:
   • Secure Key Storage:
     • Use secure vaults like AWS Secrets Manager or Google Secret Manager to store keys.
   • Limit Key Permissions:
     • Apply the principle of least privilege to key management policies:jsonCopyEdit{ "Effect": "Allow", "Principal": { "AWS": "arn:aws:iam::<account-id>:role/TrustedRole" }, "Action": "kms:Decrypt", "Resource": "*" }
   • Enable Key Rotation:
     • Configure automatic key rotation in AWS or Google Cloud:
       • AWS:bashCopyEditaws kms enable-key-rotation --key-id <key-id>
       • Google Cloud:bashCopyEditgcloud kms keys update <key-name> --keyring=<key-ring-name> --location=<location> --rotation-period=30d
   • Monitor Key Usage:
     • Enable logging to track key usage:
       • AWS: Use CloudTrail to log all KMS API calls.
       • Google Cloud: Enable Cloud Audit Logs for key operations.
   • Regular Key Audits:
     • Periodically review key policies and permissions to ensure compliance with security standards.

---

Conclusion:

This exercise demonstrates how improper encryption key management can expose sensitive data in cloud environments. By securing key storage, limiting permissions, and enabling key rotation and logging, organizations can mitigate risks and ensure robust encryption practices.