Vendor Email Compromise (VEC): How to Stop Attacks from Trusted Vendors
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Vendor Email Compromise (VEC) is a targeted cyberattack where threat actors infiltrate or spoof trusted vendor accounts to deceive your team. These attacks bypass traditional filters and exploit supply chain trust, leading to financial fraud and data breaches.
This guide breaks down how VEC works and the exact steps you need to block it.
Key Takeaways
- Vendor Email Compromise (VEC) exploits trusted vendor relationships to bypass filters and deliver targeted phishing, malware, or fake invoice attacks.
- VEC attacks are rising, often using real vendor accounts or convincing spoofed domains to evade traditional email defenses.
- Legacy security methods like basic filters and unauthenticated email (no SPF/DKIM/DMARC) are ineffective against modern VEC tactics.
- The business impact is severe, including financial loss, data breaches, reputational damage, and potential compliance violations.
- Defense requires a layered strategy: Email authentication (SPF, DKIM, DMARC), vendor risk management tools, and behavior-based monitoring.
- Proactive user training and inbox monitoring are critical to detecting and responding to attacks that slip past initial defenses.
What is Vendor Email Compromise
Vendor email compromise is a specific type of business email compromise (BEC) whereby a threat actor targets a particular business via its third-party vendors.
Lifecycle of Vendor Email Compromise Attacks:
- Attackers typically use social engineering or brute force to compromise the email accounts of vendors
- Compromised accounts are used to send fake messages to people at the target organization.
- These could contain fake invoices, requests to access sensitive resources, or even downloads containing forms of malware like spyware or ransomware.
- Attacks are highly targeted and seek to take advantage of a common blind spot by exploiting the trust between vendor and client.
Business Impact
- Financial losses
- Operational disruption
- Regulatory penalties from data protection authorities
- Reputational damage
Why Traditional Defenses Fail Against Modern VEC Attacks
BEC now accounts for 73% of reported cyberattacks, making it the top email-based threat to organizations.
Yet most businesses still rely on outdated security practices like basic filters or traditional authentication checks, which do little to stop Vendor Email Compromise (VEC).
Yet most businesses still rely on outdated security practices like basic filters or traditional authentication checks, which do little to stop Vendor Email Compromise (VEC).
❌ Basic Spam Filters – Miss well-crafted, targeted emails.
❌ Weak Email Authentication – Lack of SPF, DKIM, or DMARC allows domain spoofing.
❌ Over-Reliance on Vendor Trust – Employees don’t question requests from “known” senders.
Why VEC is Dangerous:
- Uses real vendor accounts to send malicious emails
- Bypasses spam filters and even mimics legitimate domains
- Exploits trust in the supply chain
Legacy protections aren’t enough:
To stop modern VEC attacks, you need:
- Domain-level email authentication (SPF, DKIM, DMARC enforcement)
- Ongoing monitoring of vendor domains
- Threat intelligence tied to real-time spoof detection
Action Required: Shift to proactive email security, block spoofed senders and monitor vendor behavior to reduce VEC attacks.
Defending Your Company Against VEC Attacks
You can deploy the following technologies and best practices to minimize VEC attack risks:
- Use Advanced Authentication
Prevention is the best course of action for dealing with VEC attacks. This is where advanced email authentication protocols like SPF, DKIM, and DMARC excel. SPF checks that incoming emails are sent from authorized servers, while DKIM prevents messages from being tampered with in transit. DMARC ensures that vendor domains are correctly aligned, blocking impersonation attempts.
- Engage in Vendor Risk Management
Vendor risk management is all about systematically identifying and mitigating third-party risks. This requires you to monitor the security posture of vendors, which can admittedly be labor-intensive. There are purpose-built vendor risk management software that can help you to streamline things significantly.
- Monitor Inboxes and User Activity
In addition to taking preventative measures against VEC attacks, you should also have detection and response systems in place in case something slips through the net. This is where email monitoring tools and SIEM (Security Information and Event Management) systems can help. They maintain complete visibility over all activity on your company network.
- Establish Comprehensive Security Practices and Policies
By their nature, VEC attacks compromise a social engineering aspect, making employee awareness training essential. Staff should be provided with regular orientation on what VEC attacks involve and how to identify indicators of compromise to promote vigilance.
Protecting your supply chain with proactive email security
As businesses grow more reliant on external services and cloud platforms, vendor communication has surged, creating a prime target for attackers.
Vendor Email Compromise (VEC) is now one of the main risks with third-party vendors, especially as it easily evades traditional email defenses.
To counter this, organizations must move beyond legacy security. The solution: a layered email security strategy that combines authentication (SPF, DKIM, DMARC), behavioral monitoring, and vendor risk management.
This approach not only stops VEC attacks but also secures your supply chain for the long term.
Domain & Email Security Expert at PowerDMARC
Ahona is the Marketing Manager at PowerDMARC, with 5+ years of experience in writing about cybersecurity topics, specializing in domain and email security. Ahona holds a post-graduation degree in Journalism and Communications, solidifying her career in the security sector since 2019.
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