Colonial pipeline exposed the limits of legacy authentication

At a glance

What this is: This is Axiad's analysis of the Colonial Pipeline attack, with the key finding that legacy authentication and machine identity gaps leave critical infrastructure exposed.

Why it matters: It matters because IAM, PAM, and NHI programmes in energy, manufacturing, government, and transport now sit inside broader resilience and compliance decisions, not just login design.

By the numbers:

• 80% of identity breaches involved compromised non-human identities such as service accounts and API keys.
• 96% of organisations store secrets outside of secrets managers in vulnerable locations including code, config files, and CI/CD tools.
• 91.6% of secrets remain valid five days after the targeted organisation is notified, showing a critical gap in remediation procedures.

👉 Read Axiad's analysis of the Colonial Pipeline attack and future-proof authentication

Context

Colonial Pipeline is a reminder that authentication failure in critical infrastructure is not just an access problem. When passwords, legacy systems, and machine certificates are weak or poorly governed, attackers can turn one foothold into operational disruption with effects that extend well beyond the compromised environment.

The identity lesson is straightforward. Critical infrastructure programmes have to treat user authentication, machine identity, and lifecycle governance as one control surface, because the same weak trust assumptions can undermine both enterprise systems and the physical services those systems support.

Key questions

Q: How should organisations modernise authentication in critical infrastructure without breaking operations?

A: Start with the systems that can affect safety, continuity, or regulated service delivery, then move from password-only access to phishing-resistant MFA and stronger device authentication. Use phased rollout, parallel controls, and audit evidence so operations teams can validate behaviour before legacy methods are retired.

Q: Why do legacy systems create more identity risk than modern platforms?

A: Legacy systems often depend on older authentication patterns, limited logging, and brittle integrations that make assurance hard to prove. That means one compromised credential can reach multiple downstream systems, while the organisation lacks the visibility and lifecycle control needed to contain it.

Q: What breaks when machine identities are not governed like user identities?

A: Devices, controllers, and service endpoints become trusted by default even when their certificates, ownership, or revocation paths are weak. In practice, that creates hidden access paths that bypass human review and can be reused during an incident.

Q: Who is accountable when a third-party identity can reach critical infrastructure?

A: Accountability sits with the organisation that allows the trust path to exist and remain active. Security teams should require documented access ownership, test revocation, and verify that supplier access is auditable across the full lifecycle, not just at onboarding.

Technical breakdown

Legacy authentication and password exposure in critical infrastructure

Legacy environments often keep older authentication methods alive because replacing them is operationally difficult. Passwords remain attractive to attackers because they can be intercepted, guessed, reused, or stolen, and one successful login can open multiple downstream systems. In critical infrastructure, the problem is not only the credential itself but the persistence of systems that cannot easily support modern controls such as phishing-resistant MFA or policy-driven access review. That leaves organisations with fragmented assurance and weak visibility across high-value services.

Practical implication: identify which critical systems still depend on passwords or outdated auth flows and prioritise them for modern authentication uplift.

Machine identity management for IoT and operational technology

Operational environments depend on machines, controllers, and devices that need their own identity, not just user accounts. PKI and device certificates are used to prove a machine is trusted before it exchanges data or triggers a transaction. Without that layer, a compromised camera, robot, or endpoint can become a pivot point into the wider environment. In infrastructure settings, machine identity governance is as important as human authentication because devices often outnumber users and are harder to monitor continuously.

Practical implication: inventory device identities and certificate trust paths before assuming network segmentation alone will contain compromise.

Compliance pressure is becoming an identity modernisation driver

The article points to NIST SP 800-171, CMMC, and broader legislative pressure as signals that authentication quality is now a compliance issue as much as a security issue. Regulated sectors cannot rely on ad hoc controls when they must prove strong authentication, auditability, and documented assurance. That creates a governance challenge: modernising identity controls often requires coordinated changes across users, machines, and third-party providers, not a single product swap.

Practical implication: map legacy authentication gaps to the standards you already report against, then use that mapping to justify remediation funding.

Threat narrative

Attacker objective: The attacker aims to turn a single trust failure into operational disruption with broader societal and regulatory consequences.

1. Entry occurred through weak or legacy authentication paths that reduced the assurance required to reach critical systems.
2. Escalation was enabled by the ability to reuse one compromised access path across multiple systems and operational dependencies.
3. Impact extended beyond the network into critical infrastructure operations, creating disruption and regulatory pressure.

Breaches seen in the wild

• Reviewdog GitHub Action supply chain attack — reviewdog/action-setup GitHub Action supply chain attack exposed secrets.
• CI/CD pipeline exploitation case study — full server takeover via exposed .git directory and mismanaged CI/CD pipeline secrets.

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

NHI Mgmt Group analysis

Legacy authentication debt is an operational risk, not a technical inconvenience. The Colonial Pipeline example shows how old credentials, unsupported systems, and weak assurance combine to create a pathway into critical services. When the business depends on those services, authentication design becomes part of operational resilience, not just IAM hygiene. Practitioners should treat legacy auth as a board-level risk surface.

Machine identity is the missing control plane in many infrastructure programmes. The article correctly points to machines and IoT devices as part of the attack surface, but many organisations still govern them as if they were peripherals rather than identities. Certificates, device trust, and lifecycle discipline need the same attention as human login controls. Practitioners should align machine identity governance with the rest of their IAM and PAM model.

Compliance is now pulling identity modernisation forward. The pressure from NIST SP 800-171, CMMC, and related requirements means organisations can no longer defer authentication upgrades indefinitely. That changes the programme conversation from whether to modernise to how to sequence it without breaking operations. Practitioners should use compliance deadlines to accelerate remediation of the highest-risk authentication paths.

Critical infrastructure breaches expose identity blast radius. Once a low-assurance credential or device identity is accepted, the blast radius can extend from IT systems into physical operations and public services. That makes trust validation, device authentication, and third-party assurance part of the same governance model. Practitioners should measure where one identity can still reach too much of the environment.

From our research:

• 91.6% of secrets remain valid five days after the targeted organisation is notified, showing a critical gap in remediation procedures, according to Ultimate Guide to NHIs.
• Only 5.7% of organisations have full visibility into their service accounts, which means most remediation efforts still start with incomplete identity inventory.
• For a deeper view of breach patterns, see 52 NHI Breaches Analysis, which shows how identity exposure becomes exploitable across real incidents.

What this signals

Critical infrastructure programmes should assume that identity compromise will travel faster than operational remediation unless legacy authentication is explicitly retired. When machine identities, passwords, and third-party access are all governed separately, the result is slower containment and weaker accountability across the full service chain.

Identity blast radius: the real issue is not whether one credential can be stolen, but how far it can reach before controls stop it. That is why infrastructure operators need a joined-up view of human login policy, machine trust, and revocation discipline.

With 97% of NHIs carrying excessive privileges, per the Ultimate Guide to NHIs, the governance lesson is clear: access scope, not just authentication strength, determines how far an intrusion can spread.

For practitioners

• Replace password-only access on critical systems Move the highest-risk operational and administrative accounts to phishing-resistant MFA and eliminate lingering password-only paths where possible. Focus first on systems that can affect production, safety, or external service continuity.
• Inventory machine identities and certificate dependencies Build a complete register of devices, certificates, and trusted endpoints across operational and enterprise environments. Trace where one device identity can authenticate, what it can reach, and how it is revoked.
• Tie legacy auth remediation to compliance evidence Map each authentication gap to the standards and audit obligations you already report against, including logging, assurance, and access control requirements. Use that mapping to prioritise remediation by business impact, not by convenience.
• Review third-party trust paths in infrastructure services Check which external providers can authenticate into critical systems and whether their access is documented, tested, and auditable. Treat supplier identity as part of the same control environment as internal users and devices.

Key takeaways

• The Colonial Pipeline attack illustrates how legacy authentication can turn into operational risk when critical infrastructure depends on outdated trust assumptions.
• The scale of the problem is not limited to users, because machine identities, certificates, and third-party access can all extend the blast radius of compromise.
• Modernisation should focus on high-impact authentication paths first, with lifecycle governance and auditable revocation built into the rollout plan.

Key terms

• Legacy Authentication: Authentication built on older methods such as passwords or weak shared secrets that persist because replacement is hard. In practice, legacy authentication reduces assurance, limits visibility, and creates brittle dependencies that attackers can exploit across multiple systems once one credential is compromised.
• Machine Identity: The identity assigned to a device, workload, controller, or other non-human system so it can authenticate and be trusted. Machine identity governance covers certificates, revocation, ownership, and lifecycle control, which are essential when devices participate in critical operations or can reach sensitive services.
• Identity Blast Radius: The amount of access, systems, and business impact that can follow from a single identity compromise. In well-governed environments the blast radius is small, but excessive privilege, poor revocation, and weak trust boundaries can let one account or device influence far more than intended.

Deepen your knowledge

NHI governance, machine identity security, and identity lifecycle management are core topics in our NHI Foundation Level course, the industry's only accredited NHI security programme. If you are responsible for identity security strategy or programme maturity, it is worth exploring.

This post draws on content published by Axiad: Future-Proof Authentication: The Impact of the Colonial Pipeline Attack. Read the original.