Email Spoofing


What is Email Spoofing

Email spoofing is when someone sends an email that looks like it came from a trusted source, but actually comes from a different sender address.

This is done to trick the recipient into believing the email is legitimate, often to steal personal information, spread malware, or scam the recipient.

For example, a spoofed email might appear to come from a vendor or the CEO, but was actually sent by a hacker trying to trick the recipient as part of a business email compromise attack.

Spoofing vs. Phishing

The main difference between spoofing and phishing lies in the methods used and threat actor’s objectives:

1. Purpose

  • Email Spoofing: The primary purpose of email spoofing is to disguise the sender’s identity to make the email appear as if it’s from a trusted source. It aims to create a false sense of trust.
  • Phishing: The primary purpose of phishing attacks is to trick the recipient into divulging sensitive information or performing actions that compromise their security, such as clicking on malicious links or providing personal details.

2. Method

  • Email Spoofing: This involves altering the email header information, particularly the “From” address, to make it look like the email is from a legitimate source.
  • Phishing: This technique often uses email spoofing as one of its techniques but goes further by crafting the email content to trick the recipient into taking specific actions, such as visiting a fake website or downloading a malicious attachment.

3. Scope

  • Email Spoofing: This can be used as a standalone technique for various purposes, including spreading malware, conducting scams, or simply causing confusion. It’s not necessarily focused on stealing information.
  • Phishing: This is a broader attack strategy that uses various methods, including email spoofing, social engineering, and fake websites, to specifically steal sensitive information or gain unauthorized access.

4. Indicators

  • Email Spoofing: Indicators of spoofing often include discrepancies in the email header, unusual sender addresses that don’t match the displayed name, and generic greetings instead of personalized ones.
  • Phishing: Indicators of phishing often include urgent or alarming messages prompting immediate action, suspicious links that do not match the legitimate website, requests for sensitive information, and poor grammar or spelling mistakes in the email content.

How Email Spoofing Works

Email spoofing works by falsifying the email header to make it appear as if the email is coming from a trusted source when it’s actually coming from an attacker. Here’s a step-by-step explanation of how it typically works:

1. Crafting the Email

  • Selecting the Target: The attacker chooses the recipient(s) they want to trick, often targeting individuals within an organization or customers of a specific service.
  • Creating the Content: The attacker writes an email designed to look like it’s from a trusted source, such as a company executive, a colleague, or a known service provider. The content might include requests for information, links to malicious websites, or attachments containing malware.

2. Forging the Header

  • Modifying the “From” Address: The attacker changes the email header, specifically the “From” address, to display a trusted sender’s email address. This makes it appear as though the email is coming from that legitimate source.
  • Adjusting Other Header Fields: In addition to the “From” address, attackers might also modify other header fields such as “Reply-To” to redirect any responses to an address controlled by the attacker.

3. Sending the Spoofed Email

  • Using Email Servers: The attacker uses a compromised or misconfigured email server to send the spoofed email. They may also use specialized software that allows them to send emails with forged headers.
  • Avoiding Detection: Attackers often use techniques to avoid detection by spam filters and other security measures. This might include using reputable email servers or mimicking the style and format of legitimate emails.

4. Reaching the Recipient

  • Appearing Legitimate: When the recipient receives the email, it appears to come from a trusted source. This increases the likelihood that the recipient will open the email and take any requested actions, such as clicking a link or downloading an attachment.
  • Engaging the Victim: The recipient, believing the email is legitimate, might respond to the attacker’s requests, leading to compromised credentials, stolen information, or malware infection.

How to Detect a Spoofed Email Address

There are several technical controls that organizations can put in place to prevent spoofed emails from reaching employees. These include:

  • SPF (Sender Policy Framework): Ensures that emails are sent from authorized mail servers by checking the sender’s IP address against a list of approved IPs for the domain.
  • DKIM (DomainKeys Identified Mail): Adds a digital signature to the email header, which the receiving server can verify to ensure the email has not been tampered with and is from the claimed domain.
  • DMARC (Domain-based Message Authentication, Reporting & Conformance): Uses SPF and DKIM to provide instructions to receiving mail servers on how to handle emails that fail authentication checks. It also provides reporting capabilities to monitor and improve email authentication practices.
  • Email Gateways: Deploy email security gateways that filter incoming emails for spam, malware, and phishing emails.
  • Domain Registration: Register similar and misspelled versions of your domain to prevent attackers from using them for spoofing.
  • Threat Intelligence: Use threat intelligence services to get notified when a potential phishing domain is created. This enables security teams to take down the site before an attack.