Prevent Phishing Business Email Compromise the Right Way

Prevent phishing business email compromise by focusing on how people trust routine emails, not just on blocking bad links. Most BEC incidents start quietly. Inboxes look normal. Then one believable message lands, and money moves before anyone questions it. It does not feel like an attack. It feels like work.

We work with MSSPs that already run full security stacks, email gateways, SIEM, SOAR, the usual controls. Still, BEC slips through because attackers aim at timing, authority, and habit, not the mail server itself. Our role is to help MSSPs choose, test, and audit controls that reduce this risk without slowing daily email and payment flows. Keep reading to see how this actually works in practice.

Key Takeaway

• BEC succeeds by exploiting trust, urgency, and authority, not malware alone
• Strong email authentication and phishing-resistant MFA stop most attacks early
• Training, verification, and fast response decide whether incidents stay small

Understanding Business Email Compromise Threats

BEC attacks are patient. That’s the part that surprises people. Business Email Compromise (BEC) occurs when cybercriminals gain unauthorized access to a business email account through social engineering or spoofing and then convince employees to make fraudulent financial transfers. Attackers exploit trust and legitimate internal workflows, not malware flaws [1].

Attackers sit quietly, watching how leaders write, how vendors talk, what finance teams do when quarter-end stress hits. The email that kicks things off might not have a link or an attachment at all. 

We’ve seen incidents where everything looked clean on the surface. No malware. No URL rewrites. No obvious signs. Just a request that fit the time, the tone, and the person it “came from.” That’s why traditional rules miss it, and why organizations that only think in terms of “bad links” keep getting surprised.

The pattern is simple, though:

• Attackers copy real behavior.
• They step in right when people feel pressure.
• They count on no one slowing down to verify.

Once you see that pattern, you stop looking only for bad files and start watching for bad decisions.

Common BEC Attack Scenarios

Table Common Business Email Compromise Scenarios 

BEC Scenario	What the Email Looks Like	Primary Risk	Prevention Focus
Executive Impersonation (CEO Fraud)	Urgent wire request from CEO or CFO tone	Unauthorized fund transfer	Email spoofing defense, MFA for executives, out-of-band verification
Vendor Invoice Fraud	Legitimate invoice with changed bank details	Payments sent to attacker accounts	Email verification protocols, dual authorization payments
Payroll Diversion	Employee requests direct deposit change	Salary theft	Sender legitimacy check, HR phishing risk training
Lookalike Domain Spoofing	Internal-style request from similar domain	Trust-based fraud	DMARC reject policy, domain spoofing block
Compromised Internal Account	Normal email from real inbox	Silent long-term fraud	Compromised account detection, email forwarding rules removal

Across different MSSPs and their clients, these BEC scenarios repeat with minor variations. As shown in Table, the names, dollar amounts, and sender details change, but the underlying patterns stay the same.

Most incidents fall into a small set of plays:

• Executive impersonation / CEO fraud
  Messages appear to come from senior leadership and arrive during travel, meetings, or late hours, when verification is least likely.
  
• Invoice fraud via vendor compromise
  Legitimate vendor conversations are reused, with only the payment details changed.
  
• Payroll diversion
  HR or payroll receives routine-looking requests to update direct deposit details, often timed close to pay cycles.
  
• Lookalike domain spoofing
  Slight domain variations are used to pass quick visual checks and blend into internal threads.

In each case, the attacker relies on the same levers highlighted in the table: authority, routine, and time pressure. The technical signals may look clean, but the risk emerges when normal workflows are pushed just far enough that no one pauses to verify.

The tech still matters, but the real point of failure is how everyday decisions are made under pressure.

Why Traditional Spam Filters Are Not Enough

Spam filters do a decent job blocking bulk junk, mass marketing, obvious scams, malware-driven campaigns. BEC is built to walk straight around that.

We see this a lot in product evaluations for MSSPs:

• The email comes from a real account (often already compromised).
• The domain passes SPF and DKIM.
• DMARC may even be aligned.
• There’s no file, no weird link, just a payment instruction.

From a filter’s point of view, it’s “clean.” From a finance manager’s point of view, it’s urgent. From an attacker’s point of view, it’s perfect.

This is why BEC demands layered defenses that watch behavior, not only content. Signature-based tools are still useful, but they rarely stand alone. In practice, many MSSPs close this gap by pairing internal controls with outsourced email filtering protection that can analyze sender behavior and message context beyond basic spam scoring. 

According to the FBI Internet Crime Complaint Center (IC3) 2024 data, business email compromise was one of the top sources of reported financial loss, contributing to nearly $2.8 billion in adjusted losses in the U.S. alone [2]. 

Core Technical Controls to Prevent BEC

Technology, when tuned well, should knock out as many fake emails as possible before humans ever see them. The problem we keep running into when we audit products and deployments is not “no tools,” but half-finished setups and weak policies.

Enforcing Email Authentication (SPF, DKIM, DMARC)

Email authentication is like caller ID for mail. It doesn’t solve everything, but it makes impersonation much harder.

At a basic level:

• SPF says which servers can send mail for your domain.
• DKIM signs messages so receivers can tell they weren’t changed in transit.
• DMARC ties both together and tells receivers what to do when something fails.

We often see MSSP clients with:

• SPF records that are too broad (+all or huge lists of senders),
• DKIM set up for just some services, not all,
• DMARC set to p=none and then forgotten.

A stronger setup looks like this:

• SPF is scoped narrowly to known providers.
• Every legit mail system uses DKIM consistently.
• DMARC is reviewed regularly, so reports actually lead to clean-up.

When these are done right, spoofed domains get blocked instead of “probably allowed.”

Using DMARC Reject Policies to Stop Impersonation

Monitoring-only DMARC (p=none) is like a smoke alarm that never makes a sound. Data comes in, but attacks still pass straight through. Attackers rely on that.

We’ve watched organizations move from:

• p=none → p=quarantine → p=reject

and see domain-level impersonation drop sharply. A reject policy tells receiving mail servers:

• “If this fails authentication, don’t deliver it. At all.”

For MSSPs, we usually recommend a phased move:

1. Clean SPF and DKIM.
2. Use DMARC reports to find legitimate senders you missed.
3. Gradually move to quarantine, then reject once you’re confident.

That shift closes one of the easiest doors attackers use.

Deploying Phishing-Resistant Multi-Factor Authentication

Passwords alone are easy to steal. We’ve seen attackers harvest them through fake login pages, reused credentials, or basic password spraying. Once they get in, they sit in mailboxes, set forwarding rules, and study patterns.

Phishing-resistant MFA makes that a lot harder. Stronger methods include:

• Hardware security keys (FIDO2, WebAuthn),
• Device-bound app prompts with number matching or known device checks,
• Conditional access that blocks legacy or weak auth paths.

For BEC, we always tell MSSPs to start with:

• Executives,
• Finance,
• HR,
• And anyone with admin rights.

When those people are protected, attackers can’t just walk into the mailboxes that matter most, even if they have the right password.

Securing Email Infrastructure and Endpoints

Email doesn’t exist in a bubble. Once an attacker lands in one place, they try to move sideways. We’ve seen compromises spread through:

• Old unpatched mail gateways,
• Legacy protocols like IMAP/POP without MFA,
• Uncontrolled forwarding from mailboxes to external addresses.

Basic hygiene goes a long way:

• Keep mail servers, clients, and related plugins patched.
• Disable legacy authentication where possible.
• Monitor login locations and unusual access patterns.
• Review and remove suspicious forwarding and inbox rules.

When we help MSSPs evaluate tools, we look for products that make these checks easier to automate, instead of leaving them as once-a-year tasks.

Advanced Email Filtering and Anomaly Detection

Modern email protection isn’t just about scanning attachments. Better tools look at behavior over time.

Signals that help catch BEC include:

• Unusual sending times for a given user,
• Sudden tone changes (new urgency, secrecy, or financial language),
• New forwarding rules created quietly,
• Logins from new countries or devices.

Good platforms flag emails like:

• “CEO sending a payment instruction from a new device in a new country, at 3 a.m., with wiring language they don’t usually use.”

When we test products for MSSPs, we focus on how well they handle context, not just how many known malware samples they block. A properly tuned managed email security gateway helps surface signals like unusual timing, sender behavior shifts, and silent forwarding changes, which matter more in BEC than attachment detection alone.

Policy-Based Safeguards and Verification Processes

Even with strong tools, the last line of defense is how people actually move money and approve changes. Policy is what gives them permission to slow down, to question, and sometimes to refuse.

Out-of-Band Verification for Financial Requests

Out-of-band verification means: don’t trust the same channel that made the request. If the request came through email, confirm it another way.

For high-risk actions, we recommend habits like:

• Calling known phone numbers from a trusted directory, not from the email signature.
• Using verified internal chat or ticketing systems for confirmation.
• Writing down and logging the verification step.

We’ve watched this simple step stop large wire transfers mid-flight. The email “looked right,” but the voice on the phone said, “No, that’s not from me.”

Dual Authorization for High-Risk Transactions

One person should not be able to move large sums alone. When we review controls with MSSPs and their clients, we push for:

• Clear thresholds (for example, any transfer above $10,000 requires two approvers),
• Separation of roles (the requester is not the final approver).

This means attackers must compromise:

• Multiple people, or
• Multiple accounts, all at once, which is far harder than tricking one rushed employee.

Dual authorization doesn’t just protect money. It also protects employees who now have a policy-backed reason to say, “I can’t do this alone.”

Formal Business Email Compromise Policy

A BEC policy is not just a PDF in a folder. It’s a shared agreement about:

• Who can approve what,
• How exceptions are handled,
• How urgent requests are escalated,
• And which shortcuts are never allowed.

We’ve seen simple reminders work well:

• Small posters near finance desks,
• Short checklists pinned in tools they use daily,
• Clear language on what to do with any “urgent” payment request.

When that policy is visible and repeated, staff don’t feel like they’re “being difficult” when they ask to verify. They’re just following the rules.

Restricting Privileges and Sensitive Email Access

Least privilege is the quiet hero of BEC defense. If an attacker compromises one account but can’t reach payment systems, HR records, or executive threads, the damage stays much smaller.

Strong setups often include:

• Limited access to finance and HR mailboxes,
• Segmented systems for payments and approvals,
• Encryption for sensitive email threads.

Our work with MSSPs often includes auditing which accounts can see what, then recommending tools that give more granular control instead of “everyone in this group sees everything.”

Employee Training to Reduce BEC Risk

People are not the problem. Unprepared people are. When employees know the patterns, they start catching attacks before tools do.

Recognizing Social Engineering Red Flags

We’ve watched training sessions where once people see a few real BEC examples, they start to notice the same tells:

• Sudden urgency (“right now,” “before close of business”),
• Authority pressure (“this is from the CEO / board”),
• Requests for secrecy (“don’t loop anyone else in”),
• Slight breaks from usual process (new bank accounts, new email addresses).

Modern BEC emails are often well-written. No obvious grammar issues. That’s why we focus on context and behavior over spelling mistakes. The key question is, “Does this request match how we normally do this?”

Phishing Simulations and BEC-Specific Drills

Generic phishing tests catch some awareness gaps, but BEC needs its own drills. When we advise MSSPs, we suggest simulations that mirror:

• Real invoice flows,
• Real HR change requests,
• Real executive communication patterns.

Good drills:

• Are announced as learning tools, not traps,
• Provide fast feedback (“Here’s what you missed, here’s what you spotted”),
• Measure reporting speed, not just click rates.

Over time, we’ve seen organizations go from “nobody reports anything” to “security hears about suspicious emails within minutes.” That time shift matters.

Role-Based Training for Finance and HR Teams

Finance and HR live in the blast zone for BEC. Their training has to be deeper than a once-a-year slide deck.

We usually recommend:

• Scenario-based sessions using real-world cases,
• Run-throughs of what a fake vendor update looks like,
• Practice on how to push back on “urgent” but unverified requests.

When training feels specific to their daily work, we see engagement go up. They stop viewing it as theory and start seeing it as part of doing their jobs well.

Encouraging Immediate Reporting Without Penalty

One of the worst patterns we see is quiet shame after a click or a reply. People hesitate to report because they’re afraid of trouble. That delay gives attackers room to move.

A healthier model:

• No-blame reporting (“Thank you for telling us quickly”),
• Easy channels for alerts (a button in the mail client, a dedicated chat, a short form),
• Clear examples of when to report, even if they’re not sure.

Organizations that reward fast reporting end up with more signal, quicker containment, and fewer repeat incidents from the same techniques.

Incident Response Actions for Business Email Compromise

Even the best defenses will miss something. When they do, speed and clarity matter more than perfection.

Immediate Containment of Compromised Accounts

Once BEC is suspected, the first goals are:

• Stop the attacker’s access,
• Stop the attacker’s visibility.

Key steps we recommend and see in mature playbooks:

• Disable or lock the compromised account,
• Force password reset and MFA reset,
• Remove suspicious inbox and forwarding rules,
• Review recent login history and active sessions.

We’ve seen attackers hold onto access for weeks through quiet forwarding rules alone. Cleaning those up is often where control is actually regained.

Blocking Indicators of Compromise Across Systems

Any known piece of the attack can become a defense if shared quickly:

• Malicious or suspicious domains,
• IP addresses,
• Sender addresses or patterns,
• Unique subject lines or templates.

MSSPs that have solid tooling can push these indicators into:

• Email gateways,
• Endpoint security,
• Firewalls and DNS filters.

Automation shines here, because manual blocking in the middle of a live incident is slow and error-prone. When email-based fraud overlaps with broader compromise indicators, teams often rely on malware analysis incident response workflows to correlate email artifacts with endpoint and network signals before attackers can pivot further.

Coordinating With Financial Institutions

If money has already moved, we always tell clients: don’t wait, call the bank now. Hours matter.

A strong plan includes:

• Pre-identified bank contacts,
• A standard script or checklist for what to provide,
• A clear internal trigger (“If suspected fraud over X amount, call immediately”).

Sometimes transfers can be frozen or reversed early. The longer the delay, the more likely the funds are gone for good.

Notification and External Reporting Requirements

Different regions and sectors have different laws, but in many cases there are:

• Partners who must be told,
• Regulators who expect reports,
• Law enforcement channels that can help.

In the United States, we often see clients file with The FBI Internet Crime Complaint Center (IC3).

Legal and compliance teams should be pulled in quickly. We’ve seen better outcomes when this is rehearsed ahead of time rather than improvised during chaos.

Integrating Managed Security and Email Monitoring Providers

This is where our own work connects most with MSSPs. Many providers already manage firewalls, EDR, and SIEM, but email-focused monitoring and product selection lag behind.

We help MSSPs:

• Evaluate email security and BEC-focused tools honestly,
• Test how they handle real-world BEC patterns,
• Audit deployments to make sure features are actually turned on and tuned.

Continuous monitoring, shared playbooks, and tested integrations give MSSPs the ability to react faster, with fewer blind spots. That means fewer quiet compromises and shorter dwell time when one does happen.

FAQ

How can teams check urgent payment emails without slowing finance work?

To prevent phishing business email compromise, teams must slow down just enough to check requests. Use out-of-band verification like calling a known phone number. Add dual authorization payments so one person cannot move money alone. These simple steps support wire transfer fraud prevention while keeping finance work moving.

What email setup problems let fake executive emails get through?

Weak email setup helps executive impersonation attacks succeed. Missing SPF records setup, broken DKIM authentication, or no DMARC implementation leaves doors open. Without a reject DMARC policy, fake CEO fraud scams can reach inboxes. Strong email spoofing defense and domain checks stop many attacks early.

Why is phishing-resistant MFA important for executives?

Phishing-resistant MFA protects email accounts even if passwords are stolen. Multi-factor authentication email controls block login attempts from attackers pretending to be leaders. MFA for executives helps stop authority impersonation before damage happens. It also makes compromised account detection easier by flagging strange login behavior.

What should employees watch for besides bad links or files?

Not all phishing emails use links or malware. Employees should look for urgent email red flags, pressure to act fast, and requests to keep things secret. Grammar error phishing is less common now. Employee cybersecurity awareness helps staff question emails that feel wrong, even if they look clean.

What should teams do first when they spot a BEC attempt?

Fast action matters in BEC incident response. Lock the account, reset access, and remove email forwarding rules. Share indicators to block similar emails. Use suspicious email reporting right away. If money moved, call the bank and file a law enforcement BEC report as soon as possible.

Holding the Line Against Phishing-Driven Business Email Compromise

When you line up these layers, authentication, MFA, smart policies, trained staff, and fast response, the shape of BEC changes. Attackers still try, but they hit fewer gaps and face more people willing to pause and verify. For MSSPs, this is where real resilience is built: not by adding more tools, but by making the stack work under pressure.

Talk to MSSP Security to get expert, vendor-neutral consulting that helps MSSPs reduce tool sprawl, audit and optimize email security stacks, improve integration, and make clearer decisions. With 15+ years of experience and 48K+ projects completed, we support needs analysis, PoCs, and practical recommendations that fit real operations.

References

1. https://ico.org.uk/about-the-ico/research-reports-impact-and-evaluation/research-and-reports/learning-from-the-mistakes-of-others-a-retrospective-review/phishing/
2. https://www.nacha.org/news/fbis-ic3-finds-almost-85-billion-lost-business-email-compromise-last-three-years 

Related Articles

1. https://msspsecurity.com/outsourced-email-filtering-protection/
2. https://msspsecurity.com/managed-email-security-gateway/
3. https://msspsecurity.com/malware-analysis-incident-response/