Fraud prevention case study

AP Wire Fraud Prevention (BEC Defense) Case Study

A $120M company suffered a $400K wire fraud loss to a sophisticated business email compromise (BEC) attack. Three months later, the company had layered out-of-band verification, vendor master controls, payment authorization protocols, and a documented BEC playbook — and recovered partial loss through bank fraud claim.

Client profile: Composite case study based on a $120M revenue distribution company. The CFO's email was compromised; an attacker impersonated a vendor and redirected a $400K wire payment. Pre-incident, no out-of-band verification; post-incident, full BEC defense program.

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Company context Before — what was actually broken What Ledger Summit implemented BEC defense mechanics — the layered controls Implementation timeline Measured results

Company context

The client is a $120M revenue distribution company. The CFO's email was compromised through a phishing attack; the attacker observed payment patterns for several weeks, then impersonated a vendor (using a lookalike domain) and redirected a $400K wire payment to a fraudster-controlled account. The company discovered the fraud 11 days later when the actual vendor inquired about the unpaid invoice.

BEC (Business Email Compromise) is the most common large-loss fraud in finance per FBI IC3 statistics — billions in annual losses. The defense pattern is well-known but rarely fully implemented. We were brought in to design the program in 90 days post-incident.

$120M revenue distribution company
CFO email compromised via phishing
Attacker observed payment patterns 6 weeks
Impersonated vendor with lookalike domain
$400K wire to fraudster account
Discovered 11 days later
Bank fraud claim partial recovery: $280K
Insurance claim: deductible exceeded loss

Before — what was actually broken

No out-of-band verification on payment changes. Vendor master changes accepted via email. No dual approval on wire payments above threshold. No BEC training. Email security baseline (no MFA on CFO email; no DMARC; no business email gateway).

No out-of-band verification on payment / vendor changes
Vendor master changes via email
Wire approvals via email (no dual control)
No BEC awareness training
CFO email without MFA
No DMARC, SPF, DKIM email authentication
No business email gateway (Mimecast, Proofpoint)
No fraud detection on bank wires

What Ledger Summit implemented

A six-track BEC defense program: (1) email security hardening; (2) vendor master controls; (3) payment authorization protocols; (4) out-of-band verification; (5) BEC awareness training; (6) incident response playbook.

Email security: MFA mandatory; DMARC, SPF, DKIM enforced; business email gateway (Mimecast) deployed
Vendor master controls: change requests in-system only (no email); dual control on bank detail changes; W-9 + voided check verification on new vendors
Payment authorization: dual control on all wires above $10K; out-of-band callback for changes above $50K (call vendor at known phone number)
Out-of-band verification protocol: documented; phone numbers stored in vendor master separate from email
BEC awareness training: quarterly mandatory training; phishing simulation; CFO and AP team primary focus
Incident response playbook: detection signal definitions, internal escalation, bank notification, FBI IC3 reporting, legal counsel engagement
Fraud monitoring: Bank positive pay enabled; large wire alerts; pattern-anomaly detection
Cyber insurance review: coverage adequacy assessment, deductible vs. expected loss analysis

BEC defense mechanics — the layered controls

Layer	Control	Purpose
Email security	MFA, DMARC, SPF, DKIM, business email gateway	Reduce attack surface
Awareness	Quarterly BEC training; phishing simulation	Human-firewall hardening
Vendor master	Dual control on bank changes; in-system change requests only	Authorize legitimate changes only
Wire authorization	Dual control above threshold	Multiple eyes on every wire
Out-of-band verification	Phone callback to known number	Defeat email impersonation
Anomaly monitoring	Bank fraud alerts; pattern detection	Catch attacks in progress
Incident response	Documented playbook; bank/FBI reporting	Maximize recovery; minimize damage
Insurance	Cyber crime endorsement; adequate coverage	Financial protection if fraud succeeds

Implementation timeline

Weeks 1–2: Email security hardening: MFA, DMARC, gateway deployment
Weeks 3–4: Vendor master controls: dual-control on bank changes; cleanup of vendor master
Weeks 5–6: Payment authorization: dual control wire policy; out-of-band verification protocol
Weeks 7–8: BEC training: rollout to AP, CFO, finance, and vendor-facing teams
Weeks 9–10: Incident response playbook drafted, tested, distributed
Weeks 11–12: Fraud monitoring activation; cyber insurance review

Measured results

Metric	Before	After	Delta
BEC incidents post-implementation	—	0 in 12 months	—
Phishing simulation pass rate	~60% baseline	~95% post-training	+35 pp
Vendor master changes via email	Common	0	−100%
Wire approvals (single control)	>50%	0%	−100%
Out-of-band verification rate	0%	100% on changes	—
Mean detection time (if attack)	11 days	Hours (alerting)	—
Insurance coverage adequacy	Deductible exceeded loss	Coverage right-sized	—

Alternatives considered

Option	Time	Cost band	Strengths	Weaknesses
Big-4 forensic / advisory	3–6 months	$220K–$420K	Brand; deep methodology	Cost; over-scoped
Cyber consulting (Mandiant, KPMG)	3–4 months	$140K–$240K	Security depth	Less finance-process focus
Mimecast + internal controls	3 months	$80K–$140K (license)	Email security strong	Doesn't fix process
Ledger Summit + email gateway (selected)	12 weeks	$80K–$140K	Right-sized; finance-focused	License + maintenance

When this approach fits

$25M+ revenue with material vendor / wire activity
Recent BEC incident or near-miss
IPO-readiness, audit committee pressure on fraud risk
Cyber insurance renewal requiring control enhancement
PE-backed companies with sponsor diligence on fraud posture
Companies with international vendor relationships (BEC particularly common)

Lessons learned

BEC defense is process, not tool. Email gateway alone doesn't prevent the attack; out-of-band verification does.
Vendor master is the highest-leverage control. Most BEC attacks pivot to changing vendor banking; locking that down stops the attack.
Quarterly training, not annual. Phishing simulation cadence drives behavior change; annual training has minimal effect.
Phone callback to known number, every time. "Verified by email" is the failure mode; callback to known number defeats impersonation.
Tested incident response playbook saves recovery. Bank fraud claim has tight time windows (24–48 hours); knowing the protocol matters.

Frequently asked questions

What's the typical BEC fraud loss?

FBI IC3 reports billions in annual losses across thousands of incidents. Average per incident: $50K–$500K; large incidents reach $10M+.

How do attackers typically execute BEC?

Compromise an executive email; observe payment patterns; impersonate vendor or executive; request urgent payment redirection; exploit gap in controls (email-only verification).

What's the difference between BEC and traditional phishing?

BEC is targeted, often after weeks/months of reconnaissance; uses observed patterns; impersonates trusted parties. Traditional phishing is broad and opportunistic.

How does out-of-band verification work?

Call the vendor at a phone number stored in vendor master (not email signature); verify the change request verbally. Stops email-based impersonation cold.

What about cyber insurance?

Most policies require certain controls (MFA, dual approval) for coverage. Cyber crime endorsement specifically covers wire fraud. Review at renewal for adequacy.

What's positive pay?

Bank fraud control: company submits expected check / wire list; bank only pays items on the list. Catches forged checks and unauthorized wires.

How do you train AP team specifically?

Quarterly BEC training with examples; phishing simulation 4x / year; AP team has dedicated module on vendor change requests.

What about incident response if fraud occurs?

Documented playbook: notify bank within 24 hours (fraud claim window); contact FBI IC3 (cybercrime reporting); engage legal counsel; preserve evidence.

Can banks recover wires?

Sometimes — depends on whether fraudster account is still funded, jurisdiction, and timing. Notify bank within 24 hours for best chance; even then, recovery is partial in most cases.

What about international wires?

International wires harder to recover; SWIFT recall window typically 24 hours; cross-border legal action expensive. Out-of-band verification critical for international.

BEC fraud is the largest loss vector in finance. How exposed are you?

A 30-minute call walks your AP and wire process and tells you where the gaps are.

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