CIS Safeguard 5.5: Establish and Maintain an Inventory of Service Accounts

Written with contributions from Bryon Singh, Director of Security Operations, RailWorks Corporation

Mission: Impossible and the Mystery of Service Accounts — Why You Need an Inventory

In Mission: Impossible, Ethan Hunt and his team rely on stealth, precision, and insider knowledge to infiltrate secure systems and extract sensitive data. But imagine if the IMF (Impossible Mission Force) didn’t know who had access to what. Chaos, right?

That’s exactly what happens in many organizations when service accounts — those non-human accounts used to run applications, scripts, and automated tasks — are left undocumented and unmanaged.

What is CIS Safeguard 5.5?

Part of CIS Control 5: Account Management, Safeguard 5.5 requires organizations to:

“Establish and maintain an inventory of service accounts.”

These accounts often have elevated privileges and persistent access, making them prime targets for attackers. Without visibility, they become the cybersecurity equivalent of a rogue agent — operating in the shadows, potentially undermining your defenses.

Pop Culture Parallel: Ethan Hunt’s Access

In Mission: Impossible, Ethan often uses stolen credentials or insider access to bypass security. Service accounts, if unmanaged, offer similar opportunities to real-world threat actors. They can be exploited to move laterally, escalate privileges, or maintain persistence — all without triggering alarms.

Why an Inventory Matters

1. Visibility: You can’t protect what you don’t know exists.
2. Risk Reduction: Identifying unused or over-privileged accounts helps reduce attack surface.
3. Compliance: Frameworks like NIST, ISO 27001, and CMMC require account governance.
4. Incident Response: Knowing which accounts exist helps you detect anomalies faster.

Implementation Tips

1. Automate Discovery: Use tools like Active Directory, IAM platforms, or cloud-native services to scan for service accounts.
2. Tag and Categorize: Label accounts by purpose, owner, and associated systems.
3. Review Regularly: Schedule periodic audits to validate necessity and permissions.
4. Limit Privileges: Apply the principle of least privilege and remove interactive login capabilities.
5. Rotate Credentials: Avoid hardcoded passwords and rotate secrets using vaults like CyberArk.

Final Thought

In the world of cybersecurity, service accounts are your hidden agents. But unlike Ethan Hunt, they shouldn’t be operating off the grid. CIS Safeguard 5.5 ensures that every account is accounted for, every credential is controlled, and every mission is secure.

Resources

Here’s a link to the Account and Credential Management Policy Template for CIS Controls 5 and 6  provided free of charge from the fine folks at the Center for Internet Security:

Looking for even more detail? Here you go. If this still doesn’t satisfy your curiosity, DM me.

CIS Control 5 – Account Management

Use processes and tools to assign and manage authorization to credentials for user accounts, including administrator accounts, as well as service accounts, to enterprise assets and software.

CIS Safeguard 5.5 - Establish and Maintain an Inventory of Service Accounts

Establish and maintain an inventory of service accounts. The inventory, at a minimum, must contain department owner, review date, and purpose. Perform service account reviews to validate that all active accounts are authorized, on a recurring schedule at a minimum quarterly, or more frequently.