M&A teams are great at valuing revenue, retention, and operational efficiency. Cyber risk is different: it hides in tooling sprawl, vendor contracts, identity systems, and “temporary” exceptions that quietly become permanent. And once you close, you inherit all of it—breach history, incident response gaps, compliance exposure, and third-party dependencies. These can turn into headline risk.

The good news: cybersecurity due diligence doesn’t have to be a months-long audit to be useful. A focused, deal-friendly approach can surface the risks that change valuation, deal terms, and post-close integration priorities.

Below is BlackCloak’s cybersecurity due diligence checklist built for deal teams, with practical requests, red flags, and decision points.

M&A due diligence: What executives expect vs. what actually happens

At the executive level, M&A is about growth: market expansion, talent acquisition, product acceleration, and shareholder value. Cybersecurity is assumed to be important but manageable. Contained. Fixable after close. At least, in theory.

What executives expect

  • “They must be in good shape—no major incidents that we know of.”
  • “We can standardize our tools post-close and be fine.”
  • “Cyber is important, but it’s mostly an IT issue.”

In practice, that’s rarely how it unfolds. What deal teams often uncover is not a catastrophic failure, but something more dangerous: invisible accumulation of risk. 

A “security program” may exist—but it’s frequently a patchwork of point solutions layered over years of growth. Policies may be written but unenforced. Identity systems may lack consistent MFA coverage. SaaS sprawl may outpace oversight. Logging may be partial. Privileged access may be broader than anyone realized.

Incident history can also be misleading. “No material breaches” may technically be true—while compromised credentials circulate on the dark web, executive inboxes are routinely targeted, and third-party integrations create unmonitored pathways into sensitive systems. 

For public companies, cybersecurity governance and incident disclosure now sit squarely at the board level. That changes how acquirers must think about materiality, reporting timelines, and reputational exposure. 

How to use this checklist

Cyber diligence should create clarity, not delay. It’s impossible to audit everything. Use this list to identify the most pressing and impactful risks that can affect valuation, disclosure obligations, executive exposure, or integration stability.

To apply this checklist efficiently:

  • Prioritize what changes the deal. Focus on identity gaps, incident history, regulatory risk, and potentially ongoing data breaches to high-access personal or company accounts.
  • Request proof, not promises. A dashboard, report, or policy artifact provides more signal than verbal assurances.

Cybersecurity due diligence checklist during M&A

The following checklist highlights key cybersecurity areas that commonly influence deal risk, integration planning, and leadership exposure during a transaction.

1) Governance: who owns risk, and how is it managed?

Here, teams should assess whether security is being treated as a true business risk or simply an IT function. That alone can provide significant insight into what you can expect to find.

Ask for:

  • A clear security reporting line (who ultimately owns cyber risk?)
  • Current policies and standards (even lightweight versions)
  • A risk register and recent executive/board reporting
  • Evidence that major initiatives (new systems, vendors, acquisitions) undergo security review

What strong governance looks like: Named executive accountability, regular reporting cadence, documented risk decisions, and alignment with frameworks such as the NIST CSF “Govern” function.

Red flags: Security is “shared” informally across IT. No reporting cadence. No documented risk decisions. No visibility at the board level.

2) Incident history: what happened, what was learned, what remains

“No incidents” often means “no public incidents.” That distinction matters.

Ask for:

  • An incident log covering the last 24–36 months (including near misses)
  • Ransomware or business email compromise history
  • Cyber insurance claims
  • Forensics reports and evidence of remediation

What you’re really evaluating: Detection and response capability, and whether corrective actions were implemented—or simply discussed.

Red flags: Claims of zero incidents alongside limited logging or monitoring. Recurring issues with no structural fixes.

3) Identity and access policies

Identity is often the highest-risk, lowest-effort vulnerability.

Ask for:

  • Single Sign-On (SSO) coverage map (and ideally, what systems remain outside it)
  • MFA enforcement status—especially for email and privileged accounts
  • Privileged access controls (admin account handling, shared credentials)

Helpful validation questions:

  • Is MFA enforced for executives and administrators everywhere?
  • Are there shared or legacy credentials in use?

Red flags: No MFA for email/admin. Orphaned accounts. Contractors with standing access. A culture of broad local admin rights.

4) Third-party & supply chain risk

Many breaches originate through trusted vendors. How many vendors have access to the private data of the company you’re looking to acquire?

Ask for:

  • Tiered vendor list by criticality
  • Vendor risk assessment process and samples
  • Third parties with privileged or sensitive access
  • Contract clauses covering security and breach notification

What strong oversight looks like: Defined assessment cadence, documented vendor controls, clear notification timelines.

Red flags: No vendor review process. Broad MSP access without monitoring. Weak or absent contractual protections.

5) Executive digital exposure: The highest-value target during M&A

M&A activity creates visibility, volatility, and urgency—all conditions that threat actors exploit. During transactions, executives are disproportionately targeted through spear phishing, account takeover, and attacks on personal devices or home networks.

Ask for:

  • Executive email security posture (MFA enforcement, conditional access, phishing protections)
  • Monitoring for credential exposure or impersonation domains
  • Policies governing executive device management (corporate and personal)
  • Controls around deal-related communications and document sharing
  • Any executive-focused threat monitoring or digital risk protection program

What you’re assessing: Whether senior leadership—board members, C-suite, finance leaders, and deal principals—have hardened identities and devices, or whether they represent an unmonitored entry point into the transaction.

During high-profile corporate events, attackers often shift from broad network intrusion attempts to precision targeting of individuals. A compromised executive inbox during a deal can lead to wire fraud, leaked terms, reputational damage, or regulatory scrutiny.

Red flags: No enforced MFA for executive email. Personal devices used for deal communication without protection. No home network security or digital executive protection program.

The “first 30 days after close” M&A cyber best practices

Even strong diligence won’t catch everything. Plan for rapid stabilization:

  1. Identity lockdown: enforce MFA everywhere; disable stale accounts; protect admin paths.
  2. Endpoint coverage: get EDR + device management to near-100%.
  3. Backup/restore validation: run at least one restore test on critical systems.
  4. Vendor access review: inventory integrations and third-party access; rotate keys and credentials.
  5. Executive hardening: ensure executive devices, email, and identities are protected, even on personal devices and home networks—as breaches on any account can lead to corporate compromise.

Where BlackCloak helps M&A due diligence

Even with solid cybersecurity M&A due diligence, deal teams can inherit unseen risk—especially at the executive layer, where compromised identities, targeted phishing, and device exposure can create outsized damage fast. 

If you want an “exec-layer safety net” during and after a transaction, BlackCloak helps protect high-profile leaders and their households with Concierge Cybersecurity™ that complements your internal IT and security program—so the riskiest users don’t become the easiest entry point post-close.

Contact our team to learn more today.