What Is Email Spoofing?

A technique commonly used in phishing attacks and spams to trick users by sending emails from a forged sender address.

What Is Email Spoofing?

  • Email spoofing is a cyberattack that tricks users by sending malicious emails from forged users or trusted accounts. In spoofing attacks, senders usually forge email headers and impersonate credible and recognizable sources such as a colleague, financial institution, or enterprise. Recipients are more likely to click on the embedded malicious links or open malware attachments. By exploiting the recipient’s trust, the attacker can steal sensitive information. This identity deception attack is widely used in phishing and spam.

  • Generally, the following fields are modified or forged in email spoofing:

    • REPLY-TO: Forged name and email address
    • FROM: Forged name and email address
    • RETURN-PATH: Forged email address
    • SOURCE IP: Illegitimate Internet Protocol (IP) address

    Email systems are prone to email spoofing, as outgoing email servers have no way to identify whether the sender's address is spoofed or legitimate. Users need to manually review email headers to ensure the email is legitimate.

    Spoofing an email requires setting up or compromising a Simple Mail Transfer Protocol (SMTP) server. Attackers then manipulate their email addresses, so their phishing emails appear to be legitimate messages received from the brand, colleague, or enterprise.

    Email spoofing is one of the easiest ways to send malicious emails to users, as SMTP, a protocol used to send, receive, and route emails and attachments, lacks an authentication mechanism for email addresses.

  • Email spoofing can be carried out for several reasons:

    • To conceal the sender’s identity
    • To avoid spam blacklisting
    • To impersonate an individual or enterprise the victim knows
    • To obtain sensitive information and gain access to personal assets
    • To damage the victim's or enterprise's reputation
    • To commit identity theft
  • One of the best defenses against email spoofing is to be suspicious and alert. If there’s any doubt regarding the email or sender's legitimacy, it’s best to delete the email from your inbox and inform the trusted sender immediately. Moreover, avoid opening attachments, clicking the links included in such emails, and entering your login credentials. It’s crucial to have an updated antivirus or anti-malware to prevent email spoofing. Additionally, you can report suspicious emails to the security operations center (SOC). If your organization doesn’t have a reporting mechanism in place, contact your IT team about reporting procedures. Most organizations also use tools to help prevent account takeovers and improve account security.

  • There are various ways email spoofing can be done. However, the most common one is domain name spoofing. In this type of email spoofing, scammers impersonate the display name of the victim while leaving the email address intact.

    Example: "John Smith" <Johnsmith.cmu.edu@spambrand.com>

    Scammers can also spoof the entire email address:

    Example: "John Smith" <js1990@mailwatch.com>

    To determine if an email is malicious or legitimate, you must check the email header information. The email header consists of a significant amount of tracking information through which you can identify from where the message has traveled across the internet. Outlined below are a few tips to help you identify a spoofed email.

    • Confirm the sender's email address matches the display name: Spoofed emails look legitimate at first glance. However, when closely observed, the email header can reveal the actual status.
    • Ensure the “reply-to” header matches the source: When the recipient replies to a mail, the reply-to header is typically hidden and often overlooked when replying to an email. It’s important to check the “reply-to” email address before responding.
    • Determine the “return-path” of the email: This helps you to determine the origination point of the email and the return-path of the email that may be forged.
  • Your organization must provide training and reporting tools to their employees to protect their accounts against email spoofing attacks. The tools are critically important to spot scammers' identity, inbound attacks, and outbound impersonation. Traditional security controls like cloud-based email systems can detect and block malicious emails consisting of links or attachments. Moreover, organizations must offer identity-based protections to automatically detect, remove, and block phishing attacks, spoofed emails, BEC scams, and more.

    Standard email authentication protocols can help protect organizations and employee accounts against email spoofing.

    • Domain Keys Identified Mail (DKIM): DKIM is a technical standard email authentication protocol that enables organizations to protect email senders' and recipients' accounts from spoofing, phishing, scams, and other cyberattacks. It uses asymmetric encryption to create a private and public key pair wherein the public key is published in the domain's DNS record. It works by adding a digital signature to the header of an outgoing email. Once the receiving server receives the email with the signature in its header, the server asks for a unique public key TXT record saved in the domain's DNS record to verify whether the email is sent from that domain.
    • Sender Policy Framework (SPF): SPF is an email authentication protocol designed to protect your domain against spoofing, phishing, and other email attacks carried out by spammers. SPF enables organizations to specify the mail servers or IP addresses approved to send emails on their behalf. Once the recipient's server receives the email, the DNS records are checked to identify whether the IP address is listed in the SPF record. If it doesn’t fulfill the criteria, the email will fail in its authentication process.
    • Domain-based Message Authentication, Reporting, and Conformance (DMARC): DMARC also supplies email validation to protect domains from unauthorized usage such as email spoofing. DMARC helps prevent malicious emails by bringing visibility to whether the spoofed email should be accepted or rejected by recipients. This is done in tandem with SPF and DKIM email standards.
    • Automated identity monitoring tools: Identity monitoring tools are automated tools to prevent bad actors from accessing your credentials, system, and data. These tools monitor employee's email addresses to prevent data breaches. The tools consist of a history of past breaches with timelines and details to ensure timely protection of employee's sensitive information. Besides historic exposure check and email domain watchlist, these tools also offer private email address monitoring, IP address monitoring, comprehensive breach database, domain verification, and more. Moreover, some tools can gather logs from various sources, parse their data, and store and centralize it into a commonly readable format, so teams can quickly investigate potential threats. Additionally, you can narrow down the logs using advanced features such as visualizations, out-of-the-box filters, and responsive text-based searching for both live and historical events.
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