An attack in which a client is redirected to a rogue RPC endpoint because the mapper accepts an attacker-controlled registration. The security issue is not the protocol name itself but the assumption that registration order or interface naming proves responder legitimacy.
Expanded Definition
Endpoint Mapper Poisoning is a class of RPC trust abuse where a client accepts a responder because the endpoint mapper handed back a registration that appears valid, even though the registration was attacker controlled. The risk is not confined to one protocol family; it arises whenever discovery, binding, or service location is treated as proof of legitimacy. In NHI environments, that mistake often affects service accounts, automation brokers, and agent-to-agent calls that rely on dynamic endpoint resolution.
Definitions vary across vendors because some tooling focuses on the mapper itself while others describe the broader issue as service discovery spoofing. The operational concern is the same: identity is inferred from registration metadata instead of being verified through stronger controls such as authenticated service identities, signed configuration, or network policy enforcement. That makes the issue especially relevant in Zero Trust designs and RPC-heavy enterprise back ends. NIST’s NIST Cybersecurity Framework 2.0 is useful here because it frames the need to identify, protect, detect, and respond around trust boundaries, not convenience assumptions.
The most common misapplication is treating successful endpoint registration as responder legitimacy, which occurs when teams assume interface names or registration order are reliable signals of identity.
Examples and Use Cases
Implementing RPC discovery rigorously often introduces extra validation steps and operational friction, requiring organisations to weigh lower routing risk against added configuration and certificate management overhead.
- A Windows service lookup returns a rogue RPC endpoint because the mapper accepted a malicious registration before the real service came online.
- An internal automation agent resolves a back-end function through dynamic discovery and binds to a spoofed responder that imitates a trusted service account.
- A microservice call path uses shared infrastructure for service registration, and an attacker poisons the lookup so a privileged job runner calls the wrong endpoint.
- During incident review, responders compare the attack path with the NHI lifecycle and visibility guidance in Ultimate Guide to NHIs to see how the credentialed client was misled.
- Security teams harden the control plane by combining authenticated service registration with the discovery principles described by NIST Cybersecurity Framework 2.0.
Why It Matters in NHI Security
Endpoint Mapper Poisoning matters because NHI workloads often connect at machine speed, with little human review and many opportunities for implicit trust to compound. When the wrong endpoint is selected, service accounts can hand over tokens, call privileged APIs, or expose internal data to a responder that was never authorised. That turns discovery into a control failure, not just a routing problem.
This is especially dangerous in environments already struggling with NHI visibility. NHI Mgmt Group reports that only 5.7% of organisations have full visibility into their service accounts in the Ultimate Guide to NHIs, which means poisoned registrations can be difficult to spot before damage spreads. The issue also intersects with weak secret hygiene and overprivileged automation, because a rogue endpoint often succeeds only when the client has standing access and no independent trust check.
Organisations typically encounter lateral movement, credential exposure, or broken automation only after a service call fails or a privileged transaction is diverted, at which point endpoint mapping becomes operationally unavoidable to address.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 and OWASP Agentic AI Top 10 address the attack and risk surface, while NIST CSF 2.0, NIST Zero Trust (SP 800-207) and NIST SP 800-63 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-03 | Endpoint trust failures align with service identity and authentication weaknesses. |
| OWASP Agentic AI Top 10 | AGENT-04 | Agent tool use can be redirected through poisoned service discovery paths. |
| NIST CSF 2.0 | PR.AC-3 | Access control depends on verifying identities before granting network reachability. |
| NIST Zero Trust (SP 800-207) | SC-4 | Zero Trust rejects implicit trust in discovered endpoints or registrations. |
| NIST SP 800-63 | AAL2 | Assurance concepts help define how strongly non-human credentials should be validated. |
Verify service identity before binding to any discovered endpoint and reject unauthenticated registrations.
