Display name spoofing is a common tactic used by phishers and scammers. It involves an attacker sending an email where the visible sender name appears legitimate, often impersonating a trusted individual or brand, even if the underlying email address is different. This can be incredibly deceptive, as recipients often glance at the display name before checking the full email address.
Many organizations implement SPF, or Sender Policy Framework, as a foundational layer of email authentication. While SPF is vital for verifying the sender's IP address, a common misconception is that it also directly protects against this type of "friendly-from" or display name spoofing.
However, the reality is that SPF's scope is more limited. To truly defend against display name spoofing, a more comprehensive approach involving additional email authentication protocols like DKIM and, most importantly, DMARC, is required.
Understanding SPF's role in email authentication
How SPF works
SPF is a DNS TXT record that specifies which mail servers are authorized to send email on behalf of your domain. Its primary purpose is to prevent spammers from sending messages with forged 'Mail From' (or envelope sender) addresses, which is the address used during the SMTP transaction, not necessarily the one displayed in your email client.
When an email server receives an incoming message, it performs an SPF check by looking up the sender's domain's SPF record. It then compares the IP address of the sending server with the list of authorized IPs in the SPF record. If there's a match, SPF passes, indicating that the email originated from an approved source. You can read more about how SPF authenticates the Mail-From address in detail.
This mechanism is highly effective at preventing unauthorized servers from sending email using your domain as the envelope sender. It acts as a basic gatekeeper, ensuring that only specified servers are permitted to initiate email transmission for your domain.
SPF's fundamental limitation lies in its focus on the 'Mail From' (envelope sender) address, also known as the Return-Path. It does not directly authenticate the 'From' header, which is the user-visible address and display name shown in email clients. This distinction is critical because display name spoofing specifically exploits this gap. For a deeper dive, explore whether SPF authenticates the 'From' header directly.
In a display name spoofing attack, an attacker can craft an email where the 'Mail From' address either belongs to a legitimate, unauthenticated third-party service or is simply an address that passes SPF for a completely different domain. Crucially, the 'From' header's display name will be manipulated to impersonate someone known to the recipient, such as a CEO or a colleague. The underlying technical sender might pass SPF, but the visible name is misleading.
This means that even with a perfectly configured SPF record, an email could still pass SPF checks while carrying a spoofed display name. The recipient's email client would show a familiar name, increasing the likelihood they will open, read, and potentially act on a malicious email.
SPF focus
Authenticates the 'Mail From' (envelope sender) address.
Verifies if the sending server's IP is authorized.
Display name spoofing targets
Manipulates the 'From' header's visible name.
Bypasses SPF checks by using a technically valid 'Mail From' (or Return-Path) address.
DMARC and DKIM: The full solution
The combined power of DMARC and DKIM
To effectively combat display name spoofing, you need to implement DKIM, or DomainKeys Identified Mail. DKIM adds a digital signature to your emails, cryptographically linking the message to your domain. This signature, which is part of the email header, helps verify that the email content hasn't been tampered with in transit and that it genuinely originates from your domain.
The most robust defense comes from DMARC, or Domain-based Message Authentication, Reporting, and Conformance. DMARC builds upon SPF and DKIM by providing a framework that allows domain owners to specify how receiving mail servers should handle emails that fail authentication checks. Critically, DMARC introduces the concept of "alignment," where the 'From' header domain must align with the domains authenticated by SPF or DKIM. This is where DMARC truly shines in stopping display name spoofing, as it directly addresses the 'From' header. Learn more about how DMARC authenticates the 'From' header directly.
With DMARC in place and configured to enforce a policy like p=quarantine or p=reject, emails with a spoofed display name that don't align with your SPF or DKIM authentication will be quarantined or rejected entirely, preventing them from reaching your recipients' inboxes. Utilizing a DMARC monitoring platform like Suped allows you to gain visibility into your email ecosystem and ensure proper DMARC implementation. Our AI-powered recommendations simplify the process of identifying and fixing issues.
Enhanced DMARC protection with Suped
Suped provides unparalleled DMARC monitoring and reporting, empowering you to effectively combat display name spoofing and other email threats.
AI-powered recommendations: Get actionable insights to fix DMARC, SPF, and DKIM configuration issues.
Real-time alerts: Stay informed about potential threats and spoofing attempts as they happen.
Unified platform: Monitor DMARC, SPF, and DKIM alongside blocklist and deliverability insights.
SPF Flattening: Avoid SPF lookup limits without complex manual management.
Implementing comprehensive protection
Steps to protect your domain
To fully protect your domain against display name spoofing, your strategy must extend beyond just SPF. Start by ensuring your SPF record is correctly configured and that all legitimate sending sources are included. Then, implement DKIM for all outgoing mail, ensuring your digital signatures are valid. The final, and most critical, step is to deploy DMARC with an enforcement policy, gradually moving from p=none to p=quarantine and eventually p=reject. Regularly review your DMARC reports, which tools like Suped provide, to catch any unauthorized sending and ensure proper alignment. For guidance on transitioning your DMARC policy, see our guide on how to safely transition your DMARC policy.
Beyond authentication protocols, educate your employees about the risks of phishing and display name (or email) spoofing. Encourage them to always verify sender identities, especially for suspicious requests, and to look beyond just the display name. Implementing additional anti-spoofing protection mechanisms offered by email providers, such as Microsoft Defender for Office 365, can also add an extra layer of defense against sophisticated attacks, as detailed in Microsoft's anti-phishing documentation. Understanding the comprehensive nature of email spoofing helps in building a stronger defense.
Conclusion
Securing your email identity
While SPF is an indispensable component of email security, it's not designed to protect against display name spoofing on its own. Its role is primarily to authenticate the sending server's IP address against the 'Mail From' domain. Relying solely on SPF leaves a significant vulnerability that attackers can exploit to trick recipients.
The ultimate defense against display name spoofing lies in a layered approach, integrating SPF with DKIM and enforcing policies with DMARC. This trifecta ensures that both the technical sender and the visible 'From' header are authenticated, providing a robust shield against impersonation and phishing attempts. Tools like Suped are designed to help you implement and monitor these critical protocols effectively.
Microsoft Defender for Office 365, can also add an extra layer of defense against sophisticated attacks, as detailed in Microsoft's anti-phishing documentation. Understanding the comprehensive nature of email spoofing helps in building a stronger defense.
