Default credentials and hardcoded keys undermine device identity because they are predictable, reusable, and difficult to control once deployed. If attackers can reuse the same secret across many devices, a single compromise can expose an entire fleet. PKI reduces that exposure by binding each device to a cryptographically verifiable identity and allowing certificate-level lifecycle control.
Why default credentials and hardcoded keys fail so badly in IoT fleets
IoT environments amplify a simple secret-management mistake into a fleet-wide trust failure. Default credentials are often shipped unchanged, while hardcoded keys are embedded into firmware, apps, or device images and then copied everywhere. That creates a predictable, reusable access path that is difficult to discover, rotate, or revoke once devices are deployed at scale.
Because IoT devices are frequently remote, resource-constrained, and difficult to update, the same secret can survive long after the original deployment. If an attacker learns one device secret, that secret often becomes a template for attacking many more devices, especially when vendors reuse credentials or keys across product lines, tenants, or environments.
Cryptographic identity helps because it replaces shared, static access material with per-device credentials that can be issued, tracked, rotated, and revoked individually. A certificate-based model does not remove operational complexity, but it narrows the blast radius and gives defenders a way to prove which device is authentic rather than trusting a factory default or an embedded secret.
Why the blast radius is so large in practice
The core problem is not just that the secret is weak, it is that the secret is shared, durable, and often invisible to operators. In an IoT fleet, a default password or hardcoded API key can exist across thousands of devices, making compromise of one unit materially relevant to the rest. The more identical the secret, the less meaningful the device boundary becomes.
This is why secrets management guidance for hardcoded credentials matters so much in device ecosystems, because secrets that are baked into software or firmware are not normal configuration values, they are latent access privileges. Guide to the Secret Sprawl Challenge is useful here because the same failure pattern shows up when credentials are duplicated, hidden, and hard to inventory.
Hardcoded keys also fail at lifecycle control. If a key is embedded in shipped code or firmware, rotation becomes a release problem rather than a simple security action. That is why Guide to NHI Rotation Challenges maps well to IoT fleets: the operational burden of rotating secrets rises quickly when devices are already in the field, intermittently connected, or managed by multiple teams.
By contrast, per-device cryptographic material is designed to be controlled individually, which is why Cryptographic Key Management Guide is relevant when you need to manage issuance, rotation, and revocation rather than merely store a shared secret somewhere safer.
What attackers do with default credentials and hardcoded keys
Attackers usually do not need a sophisticated exploit when the access path is already known. A default login can be tried at scale, and a leaked or guessed hardcoded key can be reused to authenticate, enumerate devices, or pivot into adjacent services. Once one credential works, the attacker often has a foothold that looks legitimate to the device or backend.
The same weakness can also support lateral movement and persistence. If a key is reused across devices, environments, or vendors, the attacker can keep returning through the same trust relationship even after one device is remediated. Top 10 NHI Issues and Ultimate Guide to NHIs, Key Challenges and Risks both help explain why reuse, overprivilege, and visibility gaps make compromise much harder to contain.
When hardcoded secrets are exposed in shipped software, public repositories, or extracted firmware, the issue can become a supply-chain style exposure rather than a single-device event. Hard-Coded Secrets in VSCode Extensions illustrates the broader pattern of a secret being copied into many downstream consumers, which is exactly what makes fleet compromise so efficient.
How to reduce the failure mode without pretending it disappears
The best answer is to eliminate shared secrets where you can and make the remaining ones short-lived, unique, and revocable. For IoT, that usually means provisioning each device with its own identity, avoiding factory defaults in production, and separating device bootstrap from ongoing authentication. If the environment still depends on a shared secret, treat it as a transitional risk, not a stable design.
OWASP Non-Human Identity Top 10 is directly relevant because it frames the exact failure patterns practitioners need to prevent: secret leakage, overprivileged identities, insecure authentication, and long-lived secrets. For device fleets, those are not abstract issues, they are the conditions that turn one compromise into many.
For implementation detail, OWASP Cheat Sheet Series is a useful reference point for secure handling of authentication material, while NIST Cybersecurity Framework 2.0 supports the broader governance view of identifying, protecting, detecting, responding, and recovering from credential-related failures.
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 addresses the attack and risk surface, while NIST SP 800-53 Rev 5 and CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-02 — Secret Leakage | Default and hardcoded device secrets are leaked or reused access material. |
| NHI-05 — Overprivileged NHI | Shared IoT secrets often grant broader access than each device needs. | |
| NHI-07 — Long-Lived Secrets | Hardcoded keys and defaults persist across deployments and are hard to revoke. | |
| Recommendation — Remove embedded secrets and rotate any exposed device credentials immediately. Scope each device credential to the minimum backend access required. Replace durable device secrets with short-lived, revocable credentials. | ||
| NIST SP 800-53 Rev 5 | IA-9 — Identification and Authentication (Non-Organizational Users) | IoT devices authenticate as non-organizational entities and need unique auth controls. |
| IA-5 — Authenticator Management | The issue is lifecycle control over embedded credentials and keys. | |
| AC-6 — Least Privilege | Reusable device secrets often enable excess access across a fleet. | |
| Recommendation — Use device-specific authentication instead of shared default credentials. Enforce issuance, rotation, revocation, and expiry for all device authenticators. Limit each device credential to only the permissions it needs. | ||
| CIS Controls v8 | CIS-5 — Account Management | IoT default accounts and reusable secrets require strong lifecycle governance. |
| CIS-6 — Access Control Management | Fleet access depends on controlling who and what can authenticate successfully. | |
| Recommendation — Inventory, disable, and replace default accounts and shared device credentials. Restrict device access paths and revoke exposed credentials quickly. | ||
Practitioner Guidance
What to prioritise: Treat any shared credential that can unlock multiple devices as a fleet-risk issue, not a device hygiene issue. The first question is whether the secret is reusable across units, environments, or product generations; if it is, blast-radius reduction comes before convenience.
What to verify: Confirm that each deployed device has a unique identity path, that bootstrap credentials are not still active after enrollment, and that revocation is actually enforced at the backend. If a compromised device can still authenticate after reset or redeployment, the control is not real.
Common mistake: Teams often focus on storage security while leaving the secret model unchanged. Protecting a hardcoded key better does not fix the fact that the same key exists everywhere, and that design choice is the real failure mode.
Practitioner takeaway: In IoT, the danger is not only secret exposure, it is secret uniformity. The safer design is one where compromise is local, rotation is possible, and authentication proves a specific device rather than a shared manufacturing default.
Related resources from NHI Mgmt Group
- Why do leaked or default credentials create such high risk in OT environments?
- Why do exposed API keys and tokens create such a high-risk failure mode in software delivery?
- Why do compromised admin credentials create such a high-risk failure mode for organisations?
- Why do hard-coded service account credentials create such a high breach risk?
Deepen Your Knowledge
Reviewed and updated by the NHIMG editorial team on September 27, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
