API security best practices are really identity governance

At a glance

What this is: This is StrongDM’s API security overview, and its central finding is that broken authentication, weak monitoring, and overexposed APIs turn identity flaws into data-breach paths.

Why it matters: It matters because API security is now an identity governance problem across service accounts, tokens, and human access patterns, not just an application hardening task.

By the numbers:

• In 2022 companies lost an estimated $4.35 million per data breach.

👉 Read StrongDM's API security checklist and best-practice guidance

Context

API security is the set of controls that prevents APIs from being misused, impersonated, or exposed through broken authentication, weak encryption, and poor visibility. In identity terms, that means the access paths connecting applications, services, and users must be governed as seriously as the applications themselves.

The governance gap is that many organisations still treat APIs as a developer concern rather than an identity and access control boundary. That leaves token handling, least privilege, and logging decisions fragmented across teams, which is exactly where abuse, leakage, and lateral movement begin.

Key questions

Q: How should security teams handle API keys and tokens as part of identity governance?

A: Security teams should treat API keys and tokens as governed identities, not just technical secrets. That means assigning ownership, defining scope, logging use, and removing credentials when the business process ends. The same lifecycle logic used for service accounts applies here, because stale API credentials are a common path to misuse and data exposure.

Q: Why do broken API authentication controls create such a large breach risk?

A: Broken API authentication is dangerous because a valid caller can be accepted before any deeper control has a chance to stop abuse. Once a token or key is trusted, an attacker can access the same functions and data that the legitimate integration can reach, which makes overprivilege and stolen credentials especially costly.

Q: What do organisations get wrong about API logging and monitoring?

A: Many teams log traffic but not identity behaviour. That leaves them blind to patterns like token replay, unusual source changes, and repeated authentication failures. Effective monitoring should answer who called the API, from where, how often, and whether the pattern matches the intended integration.

Q: How do you know if API access is too broad?

A: API access is too broad when the calling system receives more data or more privilege than it needs for the transaction it performs. A practical test is to compare the API response, the caller’s business purpose, and the minimum fields required. If those do not align, the access boundary is oversized.

Technical breakdown

Broken API authentication and token abuse

API authentication fails when a caller can present stolen, weak, or improperly validated credentials and still be treated as trusted. In practice, the risk is often not the API itself but the credential layer behind it, especially bearer tokens, API keys, and delegated access that are reused across systems. If authentication does not bind the caller tightly enough to identity, context, and permitted scope, an attacker can impersonate a legitimate integration and move directly into data access or administrative actions.

Practical implication: tighten authentication boundaries around every API credential class, especially where tokens can be replayed or reused.

Excessive data exposure and weak access scope

Excessive data exposure happens when APIs return more fields, records, or privileges than the calling application actually needs. This is an access design problem, not just a payload problem, because overbroad responses expand blast radius when a token is compromised or an integration is over-permissioned. Zero Trust and least privilege are relevant here, but they only work when the API contract, authorization layer, and data classification are aligned. Otherwise, every successful call leaks more than the business intended.

Practical implication: review API responses and entitlements together so access scope matches the minimum data required.

Logging, rate limits, and detection of misuse

Inadequate logging and monitoring turn API abuse into a silent problem. If you cannot see unusual call volumes, abnormal source patterns, or repeated authentication failures, you lose the chance to detect token theft, scraping, or automation-driven abuse early. Rate limiting is useful because it creates friction and exposes abuse patterns, but it is only effective when paired with event logging and alerting that can distinguish normal integrations from suspicious replay or enumeration behaviour.

Practical implication: pair rate limits with identity-aware logging so anomalous API behaviour is visible before data loss spreads.

Threat narrative

Attacker objective: The attacker wants to turn a valid API trust path into persistent access to sensitive data or operational systems.

1. Entry begins when attackers exploit broken API authentication or stolen tokens to appear as a trusted caller.
2. Escalation follows when the authenticated session exposes excessive data or permissions that let the attacker access more than the original use case required.
3. Impact occurs when the attacker extracts sensitive records, disrupts services through abuse, or pivots into broader breach activity through the API pathway.

Breaches seen in the wild

• Cisco DevHub NHI breach — IntelBroker exploited exposed Cisco credentials, API tokens and keys in DevHub.
• Codefinger AWS S3 ransomware attack — Codefinger used compromised AWS credentials to encrypt S3 buckets via SSE-C.

Read our 52 NHI Breaches Analysis report for a comprehensive view of breaches impacting Non-Human Identities including AI Agents.

NHI Mgmt Group analysis

API security is identity governance with an application surface area. The article correctly points to authentication, access control, and monitoring, but the deeper lesson is that APIs are simply where identity decisions become machine-executable. When tokens, keys, and delegated access are not governed as identities, the breach surface expands beyond the application team and into every system that trusts the API.

Excessive data exposure is often a privilege design failure, not a data bug. APIs leak most dangerously when permissions, schemas, and response payloads are designed in isolation. That creates a widening identity blast radius where a single valid token can unlock records far beyond the intended business transaction, which is exactly the failure mode Zero Trust is meant to constrain.

Broken API authentication is the same control failure that drives much of NHI compromise. Service accounts, API keys, and bearer tokens are non-human identities, and they fail when authentication is treated as a one-time gate instead of an ongoing trust boundary. The implication is that API security and NHI governance should be handled as one control plane, not two separate programmes.

API rate limits are necessary, but they are not a substitute for identity-aware detection. Limiting call volume can slow abuse, yet it does not tell you whether a token is legitimate, overprivileged, or being replayed from an unexpected environment. Teams need to treat API telemetry as evidence of identity behaviour, not just traffic behaviour, or they will miss the early signs of misuse.

Identity lifecycle for APIs is still the overlooked control surface. Older APIs, stale keys, and deprecated integrations remain exploitable long after the original project is forgotten. The discipline here is not only access provisioning but removal, ownership clarity, and periodic validation that every API credential still belongs to a live business process.

From our research:

• Two-thirds of enterprises have endured a successful cyberattack resulting from compromised non-human identities, with a quarter encountering multiple attacks, according to The 2024 ESG Report: Managing Non-Human Identities.
• More than 1 in 5 non-human identities are believed to be insufficiently secured, which shows how quickly unmanaged machine access becomes normalised across large environments.
• For a broader breakdown of the control failures behind these breaches, see 52 NHI Breaches Analysis for recurring patterns in exposure, overprivilege, and lifecycle gaps.

What this signals

API security is converging with NHI governance faster than most programmes are structured to handle. Once service accounts, tokens, and integration keys are treated as operational identities, the old split between application security and IAM stops making sense. Teams that keep these controls separate will struggle to explain ownership, scope, and offboarding when an API credential is reused outside its intended business flow.

In practice, the next maturity step is not more policy, but better identity observability. If you cannot see which integrations are active, which credentials are stale, and which endpoints return unnecessary data, you are managing exposure by assumption. That is why programmes aligned to NIST Cybersecurity Framework 2.0 and the OWASP Non-Human Identity Top 10 tend to produce clearer accountability around API risk.

Deep visibility into machine access creates a practical control signal for boards and auditors. When identity telemetry shows how many API paths are live, who owns them, and which ones have not been reviewed recently, governance becomes measurable rather than aspirational. That shifts the conversation from generic breach fear to concrete lifecycle control.

For practitioners

• Inventory every API credential class Map API keys, bearer tokens, service accounts, and certificates to the business process that owns them. Remove orphaned credentials and require a named owner for each integration path so stale access cannot survive by default.
• Bind API permissions to minimum response scope Review which fields and records each API can return, not just which endpoints it can call. Reduce payloads, mask sensitive attributes, and separate administrative functions from read paths where possible.
• Pair logging with identity-aware anomaly detection Capture authentication failures, unusual call bursts, new source locations, and repeated token reuse as identity signals. Feed that telemetry into alerting so suspicious API behaviour is visible before data exfiltration becomes large-scale.
• Treat deprecated APIs as active risk Retire outdated endpoints on a tracked schedule and confirm that old tokens, routes, and test integrations are revoked when the API is no longer part of a supported business flow.

Key takeaways

• API security failures are usually identity failures first, because APIs trust tokens, keys, and delegated access as callers.
• The scale of the problem is material, with breach costs averaging $4.35 million in the source article’s cited data.
• Organisations need to manage API credentials, payload scope, and telemetry as one governance surface, not three disconnected controls.

Key terms

• Application Programming Interface: An API is a defined communication layer that lets software systems request data or actions from one another. In security practice, it becomes an identity boundary because callers often authenticate with tokens or keys that must be scoped, monitored, and retired like any other access credential.
• Broken Authentication: Broken authentication is a failure in how a system proves that a caller is who or what it claims to be. For APIs, that often means weak token handling, replayable credentials, or poor validation of delegated access, which allows unauthorised callers to act as trusted integrations.
• Excessive Data Exposure: Excessive data exposure occurs when an API returns more information than the caller actually needs. The issue is usually a design and authorization problem rather than a coding typo, and it increases breach impact because a stolen credential can reveal far more data than intended.
• Non-Human Identity: A non-human identity is any machine-based or software-based identity used to authenticate and authorise access, including service accounts, API keys, tokens, certificates, bots, and workloads. These identities must be governed through ownership, scope, lifecycle, and monitoring controls because they often operate without human review at execution time.

Deepen your knowledge

API security and non-human identity governance are core topics in our NHI Foundation Level course, the industry's only accredited NHI security programme. If your environment relies on service accounts, API keys, or delegated integrations, this is the right starting point.

This post draws on content published by StrongDM: What is API Security? Risks, Checklist, and More. Read the original.