Business email compromise is one of the most dangerous cyber threats facing modern organisations. Unlike traditional spam, a business email compromise attack can involve a legitimate employee account, carefully researched messages and highly convincing requests.
An attacker may gain access to an employee’s mailbox and monitor conversations before sending fraudulent payment instructions, requesting sensitive information or impersonating an executive.
The most important defence is not simply knowing that BEC exists. Businesses need to understand how to detect business email compromise before the attacker has enough time to cause serious damage.
What Is Business Email Compromise?
Business Email Compromise, commonly called BEC, is a cyberattack where criminals manipulate or compromise business email communications to deceive employees.
The attacker may impersonate:
- A company director
- Finance staff
- A supplier
- A customer
- An employee
- An external business partner
The objective can vary from stealing money to obtaining confidential information or gaining access to additional systems.
A BEC attack does not always require sophisticated malware. In many cases, the attacker relies on stolen credentials, social engineering and knowledge of the organisation’s normal communication patterns.
Why Is BEC Difficult to Detect?
One reason business email compromise is so effective is that the messages can look completely normal.
An attacker may already know:
- Who works in the finance department
- Which employees approve payments
- Which suppliers the company uses
- When invoices are normally paid
- How executives communicate
- What projects the organisation is working on
This makes BEC different from obvious phishing emails containing spelling mistakes or suspicious attachments.
A compromised account can make fraudulent messages appear much more trustworthy.
7 Warning Signs of Business Email Compromise
1. Unexpected Payment Requests
A sudden request to transfer money should always receive additional verification.
Be particularly cautious when the request involves:
- A new bank account
- Urgent payment
- Large invoice
- International transfer
- Change of supplier details
- Unusual payment instructions
The safest approach is to verify the request through an independent communication channel.
2. Sudden Changes to Bank Details
Changing payment information through email is a major warning sign.
Even if the email appears to come from a known supplier, employees should verify the change using previously known contact information.
Do not use the phone number provided in the suspicious email for verification.
3. Unusual Login Activity
Unexpected sign-ins can indicate that an account has been compromised.
Security teams should investigate:
- New locations
- Unusual devices
- Impossible travel patterns
- Multiple failed login attempts
- Sign-ins at unusual times
- Unexpected authentication activity
One unusual login does not automatically mean an account has been hacked, but it can be an important signal when combined with other indicators.
4. Unexpected Mailbox Rules
Attackers may create email forwarding or inbox rules after compromising an account.
These rules can hide messages from the legitimate user or automatically forward sensitive communications to the attacker.
Unexpected mailbox rules should therefore be investigated promptly.
5. Messages Sent Without the User’s Knowledge
An employee may discover that emails were sent from their account even though they did not send them.
This can indicate account compromise.
Check sent items, deleted items and mailbox activity when investigating suspicious behaviour.
6. Pressure and Urgency
BEC attackers often create urgency.
Examples include:
- “Please complete this today.”
- “I’m currently unavailable.”
- “This payment is confidential.”
- “Do not call me.”
- “We need this processed immediately.”
Urgency reduces the time employees have to question the request.
7. Unexpected Requests for Sensitive Information
A request for payroll information, customer records, credentials or internal documents should be carefully verified.
Sensitive information should never be disclosed simply because a request appears to come from a senior employee.
How Businesses Can Detect BEC Earlier
Effective detection requires more than employee awareness.
Businesses should combine:
Identity monitoring + email security + user awareness + investigation + verification procedures
Security teams should monitor authentication activity and investigate suspicious changes to accounts.
Email environments should also be reviewed for unusual forwarding rules, suspicious activity and indicators of account takeover.
Why Multi-Factor Authentication Matters
Multi-factor authentication adds an additional layer of protection beyond passwords.
If an attacker obtains a password, MFA can make unauthorised access more difficult.
However, MFA should not be treated as a complete BEC solution.
Businesses should also consider:
- Strong identity controls
- Conditional access policies
- Risk-based authentication
- Account monitoring
- Security awareness training
- Incident response procedures
Create a Payment Verification Process
Technology alone cannot eliminate BEC.
Businesses should create a clear process for verifying sensitive financial requests.
For example:
- Receive the payment request.
- Check whether the request is unusual.
- Verify the recipient’s details.
- Contact the requester through an independent channel.
- Confirm the request before processing the payment.
This simple procedure can significantly reduce the risk of fraudulent transactions.
What To Do If You Suspect Email Account Compromise
If an employee believes their account has been compromised, avoid ignoring the warning signs.
The organisation should consider:
- Securing the affected account
- Reviewing recent sign-in activity
- Checking mailbox rules
- Reviewing sent and deleted messages
- Resetting credentials where appropriate
- Investigating other affected accounts
- Checking for suspicious forwarding
- Assessing whether sensitive information was accessed
- Escalating the incident to the appropriate security team
Fast investigation can help limit the attacker’s opportunity to continue operating inside the environment.
Business Email Compromise Prevention Requires More Than Awareness
Security awareness is important, but BEC prevention should be approached as a complete security process.
Organisations should combine technical controls with clear business procedures.
A strong BEC defence may include:
- Multi-factor authentication
- Secure identity management
- Email protection
- Security monitoring
- Employee awareness training
- Payment verification
- Access controls
- Incident response planning
The goal is not simply to prevent suspicious emails from arriving. The goal is to detect abnormal behaviour and stop an attacker before the incident becomes a business crisis.
Final Thoughts
Business email compromise can be difficult to identify because attackers often imitate normal business communication.
The most effective approach is to look beyond the email itself.
Unexpected payment requests, unusual login activity, mailbox rule changes, suspicious messages and urgent requests should all receive additional scrutiny.
By combining employee awareness with identity security, email monitoring and clear verification procedures, businesses can significantly improve their ability to detect BEC attacks early.
If your organisation is concerned about compromised accounts, suspicious email activity or business email security, a professional cybersecurity assessment can help identify weaknesses before attackers exploit them.
Frequently Asked Questions
What is business email compromise?
Business Email Compromise is a cyberattack where criminals impersonate or compromise business email accounts to conduct fraud, steal information or manipulate employees.
How can I detect a compromised business email account?
Look for unusual login activity, unexpected messages, mailbox forwarding rules, unfamiliar devices, suspicious payment requests and changes to normal communication patterns.
Can MFA prevent business email compromise?
MFA can significantly improve account security, but it should be combined with email protection, identity monitoring, access controls and employee awareness.
What should I do if an employee’s email account is compromised?
Secure the account, investigate authentication and mailbox activity, review suspicious messages and rules, determine what information may have been accessed and follow your incident response process.
Is business email compromise only a problem for large companies?
No. Businesses of all sizes can be targeted because attackers often select organisations based on opportunities rather than company size.
