Email Spoofing

What is Email Spoofing

Email spoofing occurs when an attacker sends an email that appears to come from a trusted source but actually originates from a different sender.

This tactic tricks the recipient into believing the email is legitimate, often to steal personal information, spread malware, or scam the victim.

For example, a spoofed email might seem to come from a known vendor or a company executive but is, in fact, sent by a hacker attempting to manipulate the recipient as part of a Business Email Compromise (BEC) attack.

Email Spoofing vs. Phishing

While email spoofing and phishing can overlap, they differ in purpose and approach:

1. Purpose

Email Spoofing: Primarily aims to disguise the sender’s identity, creating a false sense of trust in the email’s origin.
Phishing: Focuses on tricking recipients into sharing sensitive information or taking actions that compromise security, such as clicking on malicious links.

2. Method

Email Spoofing: Alters the email header, especially the “From” address, to make the email appear legitimate.
Phishing: Often includes spoofing but goes further by manipulating content to prompt actions like visiting fake websites or downloading malware.

3. Scope

Email Spoofing: May be used for various purposes, from spreading malware to causing confusion, without necessarily focusing on data theft.
Phishing: Uses various tactics, including spoofing, to explicitly target sensitive information or unauthorized access.

4. Indicators

Email Spoofing: Signs include mismatched email headers, unusual sender addresses, and generic greetings.
Phishing: Often characterized by urgent requests, suspicious links, demands for sensitive data, and frequent spelling errors.

How Email Spoofing Works

Email spoofing relies on falsifying email headers to hide the true sender. Here’s a typical sequence:

1. Crafting the Email

Selecting the Target: Attackers pick recipients, often employees or customers, to maximize impact.
Creating the Content: The email is written to mimic a trusted sender (e.g., an executive or service provider) and may include requests for sensitive data or links to malicious sites.

2. Forging the Header

Modifying the “From” Address: Attackers alter the “From” field to match a legitimate address, making the email appear trustworthy.
Adjusting Other Header Fields: Fields like “Reply-To” may also be changed to redirect replies to the attacker’s address.

3. Sending the Spoofed Email

Using Email Servers: Attackers may use compromised servers or specialized tools to send emails with forged headers.
Avoiding Detection: Tactics like using reputable servers or mimicking email formats help attackers bypass spam filters and security.

4. Reaching the Recipient

Appearing Legitimate: Once received, the email looks like it’s from a trusted source, prompting the recipient to open it and potentially follow the attacker’s instructions.
Engaging the Victim: Believing the email is genuine, the recipient may follow through with requests, leading to credential theft, malware infections, or data exposure.

Preventing Spoofed Emails

There are several technical controls that help 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.
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.