Why do service accounts and shared machine credentials increase lateral movement risk in Kubernetes and multi-cloud estates?

Why Service Accounts and Shared Machine Credentials Raise Lateral Movement Risk

Service accounts and shared machine credentials become dangerous when they are treated as reusable infrastructure convenience instead of tightly bounded workload identity. In Kubernetes and multi-cloud estates, those credentials are often mounted into pods, copied into pipelines, or reused across clusters, which means a single disclosure can unlock multiple control planes and environments. That is why the issue is not just exposure, but expansion of blast radius.

NHIMG research on the secret sprawl problem shows how quickly secrets propagate across modern estates, and the broader NHI security gap is stark: in The 2024 Non-Human Identity Security Report, 35.6% of organisations said consistent access across hybrid and multi-cloud environments was their top NHI challenge. When credentials are shared, attribution also collapses, so defenders cannot reliably tell which workload used the secret. That undermines containment, forensics, and revocation.

Industry guidance from the OWASP Non-Human Identity Top 10 and NIST Cybersecurity Framework 2.0 both point toward least privilege, strong identity assurance, and continuous control validation, but shared machine credentials work against all three. In practice, many security teams discover the problem only after a pod, pipeline, or automation token has already been reused to move laterally across namespaces or cloud accounts.

How the Risk Manifests Across Kubernetes and Multi-Cloud Operations

In Kubernetes, service account tokens can become de facto bearer tokens for API access, and if they are long-lived or broadly scoped, compromise of one workload often becomes access to adjacent workloads, secrets stores, or cluster resources. In multi-cloud estates, the same pattern repeats through shared API keys, IAM users, or cross-account roles that are copied into CI/CD systems and automation jobs. Once an attacker finds one readable credential, the path to lateral movement is often just a matter of testing which environments accept it.

The operational pattern usually looks like this:

• A workload or pipeline stores a credential in an environment variable, mounted secret, or config file.
• The credential is reused across namespaces, clusters, subscriptions, or accounts to reduce setup overhead.
• Because the credential is shared, logs show the secret was used, but not which runtime instance used it.
• If one pod, job, or node is compromised, the same credential can be replayed elsewhere until it is rotated.

Current best practice is to replace shared credentials with workload identity, short-lived tokens, and policy enforced at request time. That means using cryptographic identity for the workload itself, then issuing ephemeral access only for the task being performed. Guidance such as NIST SP 800-53 Rev 5 Security and Privacy Controls supports access enforcement, while NHIMG’s Ultimate Guide to NHIs — Static vs Dynamic Secrets explains why static secrets are the wrong primitive for dynamic workloads. Where this guidance breaks down is in legacy automation estates that cannot yet mint workload-bound tokens, because shared credentials become the fallback and the lateral movement path remains wide open.

What Security Teams Should Tighten First, and Where the Tradeoffs Are

Tighter credential scoping often increases operational complexity, requiring organisations to balance faster automation against stronger containment. That tradeoff is real in multi-cloud environments, where teams may need to redesign deployment workflows, secret distribution, and service discovery before they can eliminate shared machine credentials. Current guidance suggests prioritising the highest-risk paths first: cluster-admin service accounts, cross-account automation keys, and secrets readable from the workload runtime itself.

Not every environment can move at once, and there is no universal standard for this yet. Some platforms can adopt native workload identity quickly, while others need staged migration, token exchange, or sidecar-mediated access. The practical goal is to reduce shared blast radius even before full elimination. NHIMG’s Guide to the Secret Sprawl Challenge is useful here because it frames the problem as inventory plus control, not just rotation. The report at The 2024 Non-Human Identity Security Report also shows many organisations still rely on static approaches despite acknowledging the need for dynamic credentials.

For defenders, the priority is to make every credential answer three questions: what workload owns it, what task justifies it, and when does it expire. If any of those answers is “shared,” the lateral movement risk remains materially higher than it should be, especially in estates where pods, build agents, and cloud roles can all touch the same secrets.

Related resources from NHI Mgmt Group

• Why do service accounts and AI agents increase lateral movement risk?
• Why do service accounts increase lateral movement risk in enterprise environments?
• Why do service accounts with standing privilege increase lateral movement risk?
• Why do standing credentials increase the risk of lateral movement in cloud environments?