NIS2 Compliance Checklist 2026: Stop Web Skimming, API Key Theft, and RATs Before Regulators Call

In this Brussels dispatch, I’m laying out a practical NIS2 compliance checklist you can put to work today. Over the past week, investigators flagged a long-running web skimming operation draining checkout pages across Europe, a malicious Chrome extension siphoning crypto exchange API keys, and a new wave of AsyncRAT deliveries abusing trusted cloud infrastructure. Together they capture the NIS2 playbook: supply-chain compromise, credential theft, and resilient command-and-control. If you need a clear, up-to-date NIS2 compliance checklist that also aligns with GDPR and broader EU regulations, read on.

Why NIS2 matters right now

At today’s Brussels briefing, regulators emphasized three realities:

• Threat actors increasingly target the browser and front-end supply chain—think e-commerce skimmers embedded via third-party scripts.
• Credentials and API keys are the new crown jewels, with commodity extensions and info-stealers hoovering secrets at scale.
• Attackers blend in using legitimate infrastructure (e.g., CDN relays) to deliver remote access trojans (RATs), complicating detection and response.

NIS2, now in force across the EU with supervision ramping through 2025–2026, requires “state-of-the-art” risk management, incident reporting (early warning within 24 hours, incident notification by 72 hours, final report within one month), and governance that sticks—even on the board agenda. Fines can reach up to €10 million or 2% of global turnover for essential entities, and up to €7 million or 1.4% for important entities. Pair that with GDPR’s €20 million/4% ceiling when personal data is involved, and the business case for proactive cybersecurity compliance becomes unmistakable.

NIS2 Compliance Checklist: 15 controls to prioritize in 2026

Below is a pragmatic checklist I tested with CISOs in finance, healthcare, and critical SaaS. Map each item to your risk register, owners, and evidence for audits.

• 1) Payment page and web integrity monitoring: Deploy script integrity checks (SRI), strict Content Security Policy, and real-time monitoring for unauthorized DOM changes to stop web skimming on checkout pages.
• 2) Third-party script governance: Maintain an approved list of external scripts, pin versions, and block unapproved domains. Review analytics, tag managers, and advertising pixels quarterly.
• 3) Browser extension policy: Enforce managed browser profiles; disable unauthorized extensions. Scan for known-malicious extensions and block developer mode in enterprise settings.
• 4) Secrets and API key protection: Rotate API keys, scope permissions minimally, and store secrets in dedicated vaults. Instrument anomaly detection for trading or payment APIs to spot misuse fast.
• 5) EDR/XDR tuned for commodity RATs: Ensure behavioral rules for AsyncRAT-family persistence, lateral movement, and unusual child processes of scripting engines (Python, PowerShell).
• 6) Secure development and SBOMs: Require software bills of materials (SBOMs), signed artifacts, and pre-deployment scanning. Treat CDN-delivered code as supply chain risk.
• 7) Email and browser isolation for high-risk roles: Traders, finance, and admins should have phishing-resistant MFA and hardened browsing to curtail key theft.
• 8) Network egress controls and DNS security: Block known C2 patterns, enforce TLS inspection where lawful, and use DNS filtering to disrupt RAT beacons.
• 9) Backup, restore, and resilience: Test restores quarterly. Consider alternative connectivity paths for business continuity, including satellite or LTE failover, with clear governance for lawful use.
• 10) Vulnerability and patch management SLAs: Prioritize internet-facing assets. Track time-to-remediate and document risk acceptance for audit traceability.
• 11) Incident reporting workflow (24/72/30): Prewrite your CSIRT templates to meet NIS2’s early warning within 24 hours, incident notification by 72 hours, and final report within one month.
• 12) Supplier assurance: Classify suppliers under NIS2 exposure; require security attestations, breach notification clauses, and audit rights in contracts.
• 13) Data protection-by-design: Align security measures with GDPR’s data minimization and pseudonymization—especially for personal data in analytics and support logs.
• 14) Staff training tied to active threats: Simulate skimming and API key theft scenarios. Teach employees to recognize malicious extension prompts and fake trading tools.
• 15) Board reporting and accountability: Put NIS2 metrics (risk posture, incident SLAs, supplier exposure) on quarterly board agendas; record decisions and budgets.

Professionals avoid risk by using Cyrolo’s anonymizer to strip personal data from documents before sharing with teams or vendors. Try our secure document upload at www.cyrolo.eu — no sensitive data leaks.

GDPR vs NIS2: what changes for legal and security teams

I’m often asked by banks and hospitals whether NIS2 simply repeats GDPR. It doesn’t. Think of GDPR as governing personal data processing, while NIS2 governs the resilience and security of essential and important services, regardless of whether personal data is processed. Here’s a concise comparison:

Topic	GDPR	NIS2
Scope	Personal data processing and controllers/processors	Essential/important entities in critical sectors and digital services
Primary objective	Data protection and privacy rights	Cybersecurity risk management and service continuity
Incident reporting	Notify data protection authorities within 72 hours for personal data breaches	Early warning within 24 hours, incident notification by 72 hours, final report within one month to CSIRTs/competent authorities
Security requirements	“Appropriate” technical/organizational measures; privacy by design	Risk management measures, supply-chain security, crypto, access control, logging, and business continuity
Fines	Up to €20M or 4% global turnover	Up to €10M or 2% (essential) and €7M or 1.4% (important)
Supervision	Data protection authorities (DPAs)	Competent authorities and CSIRTs; sectoral supervision and audits
Evidence and audits	Records of processing, DPIAs, breach logs	Risk management documentation, incident reports, supplier controls, technical evidence

From headline attacks to NIS2 controls: mapping recent threats

• Web skimming at checkout: Map to controls 1–3, 6, and 12. For retailers and PSPs, integrate integrity monitoring and supplier contracts that forbid unvetted scripts.
• Malicious “trading” browser extensions: Controls 3–4, 7, and 14. Finance and crypto platforms should enforce managed extensions and detect anomalous trading via API rate/behavioral limits.
• AsyncRAT via trusted infra: Controls 5, 8, and 10. Tune EDR for script abuse, restrict egress, and prioritize patching of internet-facing apps.
• Communications resilience during disruptions: Controls 9 and 15. Business continuity plans should consider connectivity alternatives, but document lawful use and oversight.

As one CISO I interviewed in Frankfurt put it: “Our fastest wins came from killing risky extensions, pinning scripts, and rotating API keys. NIS2 gives me the mandate to make that stick.”

Practical workflow: your 72-hour NIS2 incident drill

1. Detect: SOC flags abnormal script behavior or API use. Triage with predefined criteria for NIS2 relevance.
2. Decide: Within hours, convene incident response, legal, and DPO. If likely to significantly disrupt services, prepare the 24-hour early warning.
3. Notify: Issue the early warning to the competent authority/CSIRT within 24 hours; deliver the 72-hour incident notification with known indicators and containment steps.
4. Contain and eradicate: Revoke compromised keys, block malicious domains, remove rogue scripts, and harden egress.
5. Recover: Validate clean deploys from signed artifacts; test customer-facing functionality and communications.
6. Report: Within one month, submit the final report, including root cause, impact, and planned improvements.
7. Learn: Update the risk register, supplier requirements, and training content. Brief the board.

Use AI safely in compliance workflows

Many teams now analyze incidents, draft regulator notifications, and synthesize audit evidence with AI. That’s efficient—but risky if you paste unredacted logs or customer data into generic LLMs:

• Before sharing evidence, remove personal data and secrets with an AI anonymizer.
• Centralize files in a secure document upload flow so sensitive PDFs, DOCs, and screenshots don’t leak to shadow IT.

Critical reminder: When uploading documents to LLMs like ChatGPT or others, never include confidential or sensitive data. The best practice is to use www.cyrolo.eu — a secure platform where PDF, DOC, JPG, and other files can be safely uploaded.

Professionals avoid risk by using Cyrolo’s anonymizer at www.cyrolo.eu and keeping audit artifacts compliant without exposing personal data.

Compliance checklist summary you can screenshot

• Script integrity, CSP, and payment page monitoring
• Managed browser profiles and extension controls
• Secrets vaulting, key rotation, and API anomaly detection
• EDR/XDR with RAT behavior rules; egress/DNS controls
• SBOMs and signed artifacts for the front end and back end
• Connectivity resilience with clear governance
• Supplier risk tiers, clauses, and attestations
• 24/72/30 incident reporting templates ready
• GDPR alignment: minimization, pseudonymization, DPIAs
• Role-based training tied to current threat campaigns
• Board-level KPIs and investment tracking

EU vs US: where the bar is moving

Compared with the US, where disclosure rules focus on material cyber incidents and sectoral frameworks, the EU’s NIS2 sets a prescriptive baseline for operational risk management across critical services. Expect convergence: US and EU regulators increasingly scrutinize supplier controls, identity security, and incident timelines. For multinational firms, harmonize on the stricter standard to reduce rework.

FAQ: your NIS2 compliance checklist questions answered

What is the NIS2 compliance deadline?

Member States transposed NIS2 in late 2024, with sector supervision phasing in across 2025–2026. Check your national regulator’s guidance for registration, sectoral scoping, and audit timelines—don’t assume you’re exempt.

Who falls under NIS2?

“Essential” and “important” entities in sectors such as energy, transport, banking/financial market infrastructure, health, drinking water, digital infrastructure, ICT services, and certain digital platforms. Many SaaS providers supporting these sectors are in scope via supply-chain exposure.

How does NIS2 differ from GDPR?

GDPR protects personal data; NIS2 protects the continuity and cybersecurity of services. A single incident may trigger both—e.g., a skimmer steals cardholder data (GDPR) and disrupts payment services (NIS2). Prepare to notify both authorities where applicable.

What are the NIS2 incident reporting timelines?

Early warning within 24 hours of becoming aware; incident notification by 72 hours with preliminary assessment; and a final report within one month.

How do I prepare for a NIS2 audit?

Map risks to controls, assign accountable owners, maintain evidence (policies, logs, reports), and rehearse the 24/72/30 workflow. Use a secure repository for artifacts and anonymize logs that include personal data before sharing with auditors or suppliers.

Conclusion: make your NIS2 compliance checklist actionable

The latest web skimmers, key-stealing extensions, and RAT campaigns aren’t outliers—they’re the everyday backdrop for NIS2. Turn this NIS2 compliance checklist into an implementation plan with owners, SLAs, and audit-ready evidence. And when AI helps you draft incident reports or collate evidence, protect your organization: anonymize before you share and route files through a secure channel. Start now with Cyrolo’s anonymizer and secure document upload at www.cyrolo.eu to reduce risk, meet EU regulations, and keep regulators confident in your controls.