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Business email compromise

Business email compromise targets money or data flows through manipulated business mail - often via compromised mailboxes or convincing correspondence. This page outlines scenarios and controls.

Who this page is for

Executives, finance, procurement, IT and security leaders - everywhere payments are triggered or partners coordinated by email.

What is BEC?

Business email compromise is a targeted mail-based attack. Unlike classic phishing it aims at concrete business processes - payments, deliveries, contracts or HR.

Typical scenarios

Payment redirection: known suppliers seem to share new bank details.

CEO fraud: a fake executive demands an urgent transfer.

Supplier mail thread: a compromised supplier mailbox takes over running correspondence.

Compromised internal mailboxes: attackers observe real workflows and inject at the right moment.

Controls

Phishing-resistant [MFA](/en/mfa) removes many precursors.

Four-eyes principle and out-of-band verification for bank changes.

Clear payment approval with limits.

Regular awareness for finance and procurement, see security awareness.

Mailbox rules and anomalies monitored, see Microsoft 365 security.

Reporting paths known and low-friction.

Scenario

Accounts payable receives a plausible mail from a known supplier with a new bank account. A mandatory out-of-band call exposes the attack and the payment is stopped.

Checklist

  • Phishing-resistant MFA everywhere
  • Four-eyes principle on payments
  • Out-of-band verification of new bank data
  • Mailbox rules reviewed for anomalies
  • Awareness modules for finance and procurement
  • Clear reporting paths for suspicious mails

Frequently asked questions

+Difference from phishing?

Phishing is broader and often generic. BEC is targeted and tied to specific business processes.

+Is a spam filter enough?

No. Many BEC mails are technically clean and abuse trust and processes.

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