Performing Service Account Credential Rotation
Overview
Service accounts are non-human identities used by applications, daemons, CI/CD pipelines, and automated processes to authenticate to systems and APIs. These accounts often have elevated privileges and their credentials (passwords, API keys, certificates, tokens) are frequently long-lived and shared across teams, making them prime targets for attackers. Credential rotation is the systematic process of replacing these secrets on a scheduled basis, propagating new credentials to all dependent systems, and verifying service continuity after rotation.
When to Use
- When conducting security assessments that involve performing service account credential rotation
- When following incident response procedures for related security events
- When performing scheduled security testing or auditing activities
- When validating security controls through hands-on testing
Prerequisites
- Inventory of all service accounts across AD, cloud, and applications
- Secrets management platform (HashiCorp Vault, AWS Secrets Manager, Azure Key Vault, or CyberArk)
- Service dependency mapping (which services use which credentials)
- Change management process for rotation windows
- Monitoring for service health post-rotation
Core Concepts
Service Account Types
| Type | Platform | Credential | Rotation Method |
|---|
| Active Directory Service Account | Windows/AD | Password | gMSA (automatic) or PAM-managed |
| AWS IAM User | AWS | Access Key/Secret Key | AWS Secrets Manager rotation Lambda |
| GCP Service Account | GCP | JSON key file | Key rotation via IAM API |
| Azure Service Principal | Azure | Client secret/certificate | Key Vault + rotation policy |
| Database Service Account | SQL/Oracle/Postgres | Password | Vault dynamic secrets |
| API Key | SaaS applications | API token | Application-specific API |
Group Managed Service Accounts (gMSA)
Windows gMSAs provide automatic password management by Active Directory:
- AD automatically rotates the password every 30 days
- Password is 240 bytes, cryptographically random
- Multiple servers can use the same gMSA simultaneously
- No administrator knows or manages the password
- Eliminates manual rotation for Windows services
Rotation Architecture
Secrets Manager / Vault
│
├── Rotation Trigger (schedule or on-demand)
│
├── Generate new credential
│
├── Update credential at source (AD, cloud IAM, database)
│
├── Update credential in all consumers:
│ ├── Application configuration
│ ├── CI/CD pipeline secrets
│ ├── Kubernetes secrets
│ └── Other dependent services
│
├── Verify service health
│ ├── Health check endpoints
│ ├── Authentication test
│ └── Functional smoke test
│
└── Revoke old credential (after grace period)
Workflow
Step 1: Discover and Inventory Service Accounts
Enumerate all service accounts and their dependencies:
# Active Directory: Find all service accounts
Get-ADServiceAccount -Filter * -Properties *
Get-ADUser -Filter {ServicePrincipalName -ne "$null"} -Properties ServicePrincipalName,PasswordLastSet,LastLogonDate
# Find accounts with passwords older than 90 days
$threshold = (Get-Date).AddDays(-90)
Get-ADUser -Filter {PasswordLastSet -lt $threshold -and Enabled -eq $true} -Properties PasswordLastSet,ServicePrincipalName |
Where-Object {$_.ServicePrincipalName} |
Select-Object Name, PasswordLastSet, ServicePrincipalName
Step 2: Implement gMSA for Windows Services
# Create KDS Root Key (one-time, domain-wide)
Add-KdsRootKey -EffectiveImmediately
# Create the gMSA account
New-ADServiceAccount -Name "svc-webapp-gmsa" `
-DNSHostName "svc-webapp-gmsa.corp.example.com" `
-PrincipalsAllowedToRetrieveManagedPassword "WebServerGroup" `
-KerberosEncryptionType AES128,AES256
# Install on target server
Install-ADServiceAccount -Identity "svc-webapp-gmsa"
# Test the account
Test-ADServiceAccount -Identity "svc-webapp-gmsa"
# Configure IIS Application Pool to use gMSA
# Set identity to: CORP\svc-webapp-gmsa$
Step 3: AWS Access Key Rotation with Secrets Manager
import boto3
import json
def rotate_iam_access_key(secret_arn, iam_username):
"""Rotate an IAM user's access key via Secrets Manager."""
iam = boto3.client("iam")
sm = boto3.client("secretsmanager")
new_key = iam.create_access_key(UserName=iam_username)
new_access_key = new_key["AccessKey"]["AccessKeyId"]
new_secret_key = new_key["AccessKey"]["SecretAccessKey"]
sm.put_secret_value(
SecretId=secret_arn,
SecretString=json.dumps({
"accessKeyId": new_access_key,
"secretAccessKey": new_secret_key,
"username": iam_username,
})
)
keys = iam.list_access_keys(UserName=iam_username)
for key in keys["AccessKeyMetadata"]:
if key["AccessKeyId"] != new_access_key and key["Status"] == "Active":
iam.update_access_key(
UserName=iam_username,
AccessKeyId=key["AccessKeyId"],
Status="Inactive"
)
return {"new_key_id": new_access_key, "old_keys_deactivated": True}
Step 4: Database Credential Rotation with Vault
import hvac
def configure_vault_database_rotation(vault_url, vault_token, db_config):
"""Configure HashiCorp Vault for automatic database credential rotation."""
client = hvac.Client(url=vault_url, token=vault_token)
client.sys.enable_secrets_engine(
backend_type="database",
path="database"
)
client.secrets.database.configure(
name=db_config["name"],
plugin_name="postgresql-database-plugin",
connection_url=f"postgresql://{{{{username}}}}:{{{{password}}}}@"
f"{db_config['host']}:{db_config['port']}/{db_config['database']}",
allowed_roles=[db_config["role_name"]],
username=db_config["admin_user"],
password=db_config["admin_password"],
)
client.secrets.database.create_role(
name=db_config["role_name"],
db_name=db_config["name"],
creation_statements=[
"CREATE ROLE \"{{name}}\" WITH LOGIN PASSWORD '{{password}}' VALID UNTIL '{{expiration}}';",
f"GRANT SELECT, INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA public TO \"{{{{name}}}}\";"
],
default_ttl="1h",
max_ttl="24h",
)
return {"status": "configured", "role": db_config["role_name"]}
Step 5: Post-Rotation Verification
After every rotation, verify service continuity:
import requests
import time
def verify_service_health(service_endpoints, max_retries=3, delay=10):
"""Check that services are healthy after credential rotation."""
results = []
for endpoint in service_endpoints:
for attempt in range(max_retries):
try:
response = requests.get(
endpoint["health_url"],
timeout=10,
headers=endpoint.get("headers", {})
)
healthy = response.status_code == 200
results.append({
"service": endpoint["name"],
"status": "healthy" if healthy else f"unhealthy ({response.status_code})",
"attempt": attempt + 1,
})
if healthy:
break
except requests.RequestException as e:
results.append({
"service": endpoint["name"],
"status": f"error: {str(e)}",
"attempt": attempt + 1,
})
if attempt < max_retries - 1:
time.sleep(delay)
return results
Validation Checklist
References
