How should security teams manage Service Principal Names to reduce Kerberoasting risk in Active Directory?

Security teams should treat SPNs as sensitive authentication bindings, not routine metadata. Keep service accounts tightly scoped, use long and unique passwords, rotate them regularly, and avoid assigning SPNs to high privilege identities. Prefer group managed service accounts where possible, and audit for stale, duplicate, or unnecessary SPNs because those conditions expand the attack surface and make ticket cracking more rewarding.

Why SPNs Become a Kerberoasting Target

service principal Names matter because they are the directory bindings Kerberos uses to request service tickets. When an SPN is attached to a service account with weak password hygiene, excessive privilege, or long-lived credentials, the ticket becomes worth cracking. That is why SPN governance is not just naming discipline. It is an identity control that changes how attractive Active Directory is to attackers looking for offline password recovery paths.

The real issue is not SPNs in isolation, but the combination of service exposure, privilege, and password reuse across many hosts. Security teams often discover the problem only after a service account has been reused too broadly or left untouched for years. NHI Management Group’s research on NHI risk shows why this matters operationally: the The 2024 ESG Report: Managing Non-Human Identities found that 72% of organisations have experienced or suspect a breach of non-human identities, which underscores how quickly neglected bindings can become a real attack path.

Kerberoasting is especially effective when SPNs sit on accounts that were created for convenience rather than containment. In practice, many security teams encounter this only after lateral movement is already underway, rather than through intentional SPN review.

How to Reduce Kerberoasting Risk in Practice

The safest pattern is to treat every SPN as a service boundary that deserves lifecycle control, not a one-time directory setting. Start by inventorying SPNs across the domain, then map each one to an owner, a business service, and the privilege level of the backing account. That makes it easier to remove stale bindings, consolidate duplicates, and flag accounts whose permissions exceed the service they support.

From there, reduce the value of any stolen ticket by shrinking the crack window. Long, unique passwords still matter for classic service accounts, but best practice is evolving toward managed identities such as group managed service accounts where the platform handles password rotation. Align this with the NIST Cybersecurity Framework 2.0 so SPN review sits inside routine identity governance rather than emergency response.

• Prefer gMSAs for services that support them, especially where password rotation is operationally difficult.
• Remove SPNs from high privilege identities unless there is a documented technical need.
• Rotate service account secrets on a fixed schedule, and shorten the interval when exposure is high.
• Audit for duplicate SPNs, orphaned service accounts, and accounts that have not been used recently.
• Monitor authentication activity for unusual ticket requests against service accounts that should be quiet.

Security teams should also ensure the account that hosts the SPN follows least privilege at the directory, host, and application layers. The NIST SP 800-53 Rev 5 Security and Privacy Controls provides the control structure for access restriction, credential management, and audit logging, while the Top 10 NHI Issues is useful context for the broader lifecycle failures that usually accompany weak SPN governance. These controls tend to break down when legacy applications require static service accounts with domain-wide rights and no clean path to managed identity.

Common Variations and Edge Cases

Tighter SPN control often increases operational overhead, requiring organisations to balance attack resistance against application compatibility and support effort. That tradeoff is especially visible in older Windows estates, third-party products, and cross-domain service dependencies where gMSA support is limited or absent.

Current guidance suggests handling those exceptions with compensating controls rather than accepting risk by default. If a legacy service must keep a traditional account, isolate it to the smallest possible scope, assign a unique password, enforce documented rotation, and monitor for ticket request patterns that do not match the service’s normal behaviour. Use The State of Non-Human Identity Security to justify the investment case internally: the report notes that lack of credential rotation is cited as a top cause of NHI-related attacks by 45% of organisations, which maps directly to weak service-account handling.

One edge case is delegated administration, where teams want SPNs on powerful accounts for convenience. That should be treated as an exception requiring explicit approval and periodic review, not a standard pattern. Another is multi-service hosts, where several applications share one account because separation was never designed into the environment. In those environments, SPN cleanup works only if ownership is assigned and the service architecture is gradually decomposed.

Related resources from NHI Mgmt Group

• How should security teams reduce Kerberoasting risk in Active Directory?
• How should security teams manage primary group IDs in Active Directory to reduce privilege abuse risk?
• How should security teams reduce NTLM relay risk in Active Directory?
• How should security teams reduce the risk of password guessing attacks in Active Directory?