Why do shared credentials create more risk in agentic and machine-to-machine access?

Shared credentials collapse accountability and expand blast radius. When multiple services or agents use the same secret, teams lose the ability to prove who acted, limit scope cleanly, or revoke access without breaking unrelated workflows. That is why identity-specific access and short-lived authority are more defensible than reusable secrets.

Why Shared Credentials Create Disproportionate Risk

Shared secrets look efficient, but they erase the one thing incident responders need most: attributable identity. In agentic and machine-to-machine environments, a single token may be used by multiple services, pipelines, or autonomous agents, so a compromise is no longer a single-account problem. It becomes a lateral-movement problem, because the same credential can often unlock several workflows at once. That is why OWASP’s guidance on OWASP Non-Human Identity Top 10 and NIST’s NIST AI Risk Management Framework both push teams toward identity-specific authority rather than reusable secrets.

Shared credentials also defeat targeted revocation. If one agent misbehaves, security teams cannot safely revoke the secret without potentially breaking unrelated automations that depend on the same token. That is especially dangerous in fast-moving AI workflows, where actions can chain across APIs, data stores, and admin tools in seconds. NHIMG has documented how this pattern surfaces in real incidents, including the LLMjacking: How Attackers Hijack AI Using Compromised NHIs research and the AI Agents: The New Attack Surface report. In practice, many security teams discover the blast radius only after a shared token has already been reused across several systems.

How It Works in Practice

The safer model is to replace shared credentials with workload identity, short-lived authorization, and scoped delegation. For machine-to-machine traffic, that usually means each service or agent proves what it is with a cryptographic identity, then receives just enough access for a specific task. In current guidance, this often includes ephemeral tokens, JIT credentials, and policy checks at request time rather than a broad standing grant. The operational goal is not just to rotate secrets faster. It is to make each action attributable to one workload and one purpose.

Practitioners typically combine several controls:

• Issue a distinct identity to each agent, service, or pipeline step instead of one shared token.
• Use short TTLs so credentials expire before an attacker can reuse them widely.
• Evaluate access at runtime with policy-as-code, especially when agent intent and context change per request.
• Log each secret issuance, API call, and downstream tool invocation to preserve auditability.
• Prefer workload identity standards such as SPIFFE/SPIRE or OIDC-backed service tokens for service-to-service proof.

This pattern matters even more in agentic workflows because autonomous systems can chain tools, retry actions, and escalate scope in ways that are hard to predict ahead of time. The NHIMG analysis in OWASP Agentic Applications Top 10 shows why standing credentials are brittle in those environments, while the CSA MAESTRO agentic AI threat modeling framework reinforces the need to model tool use, delegation, and blast radius together. These controls tend to break down when legacy batch jobs, shared CI runners, or monolithic integration gateways still depend on one long-lived secret for multiple unrelated functions.

Common Variations and Edge Cases

Tighter credential isolation often increases operational overhead, requiring organisations to balance stronger containment against higher provisioning and audit complexity. That tradeoff is real in environments with older middleware, vendor integrations, or scripts that were built around one shared API key. In those cases, best practice is evolving rather than universal: the immediate goal may be to segment shared credentials by function, then migrate toward per-workload identity over time.

There are also exceptions where a shared secret appears unavoidable, such as temporary migration windows or third-party systems that do not support workload identity. Even then, the safer approach is to narrow scope, shorten TTL, and wrap the secret in monitoring and revocation procedures. Industry guidance increasingly treats long-lived shared credentials as a transitional risk, not a stable design choice. NHIMG’s Ultimate Guide to NHIs 2025 Outlook and Predictions and the Moltbook AI agent keys breach both underscore the same point: once one shared secret is exposed, the attacker does not need to distinguish which agent was “supposed” to use it. They can simply use it wherever it works.

Related resources from NHI Mgmt Group

• When does just-in-time access reduce risk for agentic AI, and when does it fall short?
• When does AI agent access create more risk than it reduces?
• When do AI agent credentials create more risk than they reduce?
• How should security teams govern machine identity credentials in agentic AI environments?