Detecting Business Email Compromise

Overview

Business Email Compromise (BEC) is a sophisticated fraud scheme where attackers impersonate executives, vendors, or trusted partners to trick employees into transferring funds, sharing sensitive data, or changing payment details. Unlike traditional phishing, BEC often contains no malicious links or attachments, relying purely on social engineering. This guide covers detection techniques using email gateway rules, behavioral analytics, and financial process controls.

Prerequisites

• Email security gateway with BEC detection capabilities
• Understanding of organizational financial processes and approval chains
• Access to email logs and SIEM platform
• Knowledge of social engineering tactics

Key Concepts

BEC Attack Types (FBI IC3 Classification)

1. CEO Fraud: Attacker impersonates CEO, requests urgent wire transfer
2. Account Compromise: Employee email compromised, used to request payments from vendors
3. False Invoice Scheme: Fake invoices from "vendor" with changed bank details
4. Attorney Impersonation: Impersonates legal counsel for urgent confidential transfers
5. Data Theft: Requests W-2, tax forms, or PII from HR

Detection Indicators

• Urgency and secrecy language ("confidential", "do not discuss with others")
• New or changed payment instructions
• Executive communication outside normal patterns
• Display name matches executive but email domain differs
• Reply-to address differs from From address
• First-time communication pattern between sender and recipient
• Request for gift cards or cryptocurrency

Implementation Steps

Step 1: Configure BEC-Specific Email Rules

• Flag emails with VIP display names from external domains
• Detect financial keywords combined with urgency language
• Alert on first-time sender to finance/accounting staff
• Check for Reply-To domain mismatch

Step 2: Deploy Behavioral Analytics

• Baseline normal communication patterns per user
• Detect anomalous requests (unusual recipient, unusual time, unusual request type)
• Monitor for email forwarding rule changes (T1114.003)

Step 3: Implement Financial Controls

• Dual-authorization for wire transfers above threshold
• Out-of-band verification for payment detail changes (phone callback)
• Vendor payment change verification process
• Finance team training on BEC red flags

Step 4: Monitor for Account Compromise

• Detect impossible travel in email login locations
• Alert on email forwarding rule creation
• Monitor for mailbox delegation changes
• Check for inbox rules hiding BEC-related emails

Tools & Resources

• Microsoft Defender for O365 Anti-BEC: Built-in BEC detection
• Proofpoint Email Fraud Defense: BEC-specific solution
• Abnormal Security: AI-driven BEC detection
• FBI IC3 BEC Advisory: https://www.ic3.gov/
• FinCEN BEC Advisory: Financial institution guidance

Validation

• BEC detection rules trigger on test scenarios
• Financial controls prevent unauthorized transfers in drills
• Account compromise detection catches simulated attacks
• Reduced BEC susceptibility in awareness assessments

Compliance Framework Mapping

This skill supports compliance evidence collection across multiple frameworks:

• SOC 2: CC6.1 (Logical Access), CC7.2 (Anomaly Detection)
• ISO 27001: A.7.2 (Information Security Awareness), A.13.2 (Information Transfer)
• NIST 800-53: AT-2 (Awareness Training), SI-8 (Spam Protection), SC-7 (Boundary Protection)
• NIST CSF: PR.AT (Awareness & Training), DE.CM (Continuous Monitoring)

Claw GRC Tip: When this skill is executed by a registered agent, compliance evidence is automatically captured and mapped to the relevant controls in your active frameworks.

Deploying This Skill with Claw GRC

Agent Execution

Register this skill with your Claw GRC agent for automated execution:

# Install via CLI
npx claw-grc skills add detecting-business-email-compromise

# Or load dynamically via MCP
grc.load_skill("detecting-business-email-compromise")

Audit Trail Integration

When executed through Claw GRC, every step of this skill generates tamper-evident audit records:

• SHA-256 chain hashing ensures no step can be modified after execution
• Evidence artifacts (configs, scan results, logs) are automatically attached to relevant controls
• Trust score impact — successful execution increases your agent's trust score

Continuous Compliance

Schedule this skill for recurring execution to maintain continuous compliance posture. Claw GRC monitors for drift and alerts when re-execution is needed.