Did you know that 91% of cyberattacks begin with a phishing email? A single click on a suspicious link can put sensitive data at risk and cause serious issues for your business.

What is email security?

Email security refers to the collective measures put in place to secure the access and content of email communication against unauthorized access, compromise, or loss. Think of it as a set of defenses that guard your inbox against phishing scams, malware, and junk mail. Email security encompasses the use of encryption, authentication methods (such as SPF and DKIM), spam filters, and anti-virus software. It takes a multi-layered approach to ensure:

• Confidentiality: Only authorized recipients can access email content.
• Integrity: Email messages remain unaltered during transmission.
• Availability: Users can access their email accounts and messages reliably.

Types of attacks that occur via email

Phishing attacks

Phishing is one of the most common email attacks and involves sending deceptive emails that appear to come from legitimate sources like banks, government agencies, or social media platforms. These emails often include urgent requests, such as verifying account information, resetting a password, or resolving a billing issue, to trick recipients into divulging sensitive information. For example, between 2013 and 2015, attackers impersonated a Taiwanese hardware supplier and sent fake invoices to Facebook and Google. This resulted in over $100 million in fraudulent payments.

Attackers exploit human emotions like fear, urgency, or curiosity to manipulate recipients. For example, an email might claim, “Your account has been compromised. Click here to secure it now!” Fearful recipients may act without verifying the authenticity of the email.

• Spear phishing: This is a highly targeted form of phishing, where attackers aim at specific individuals or organizations, often after gathering personal or professional details about the target to make the attack more convincing.
• Whaling: Whaling targets high-profile individuals, such as executives, CEOs, or other decision-makers. These attacks often involve sophisticated emails that mimic official correspondence to extract critical information or authorize financial transactions.
• Clone phishing: In this method, attackers replicate a legitimate email previously sent to the victim, replacing links or attachments with malicious versions. Because the email looks familiar, recipients are more likely to trust it.

Malware distribution

Malware-laden emails contain harmful attachments, such as infected files (e.g., .exe, .zip) or links to malware-hosting websites. Unsuspecting users who open these attachments or click the links risk infecting their devices with viruses, spyware, ransomware, or other malicious software.

The consequences of malware attacks are extensive and can range from stealing sensitive information to disabling entire systems. For example, in 2017, the "DHL Delivery" phishing campaign tricked recipients into opening email attachments disguised as invoices. These attachments installed the banking Trojan TrickBot, compromising users' devices and financial data. Such attacks showcase the growing sophistication of email-based malware distribution tactics.

Business Email Compromise

BEC attacks use highly sophisticated social engineering techniques where cybercriminals impersonate company executives, trusted partners, or other authoritative figures. Their goal is to manipulate employees into performing unauthorized actions, such as transferring funds, sharing sensitive data, or granting access to internal systems.

One notable example is the attack on Ubiquiti's Hong Kong subsidiary, where cybercriminals posed as executives and convinced a finance department employee to transfer funds. Believing the transfers were part of a confidential acquisition process, the employee made multiple payments to fraudulent accounts over 17 days, resulting in significant financial losses.

BEC attacks often lead to devastating financial and reputational damages for organizations, underscoring the importance of robust email security measures and employee training.

Ransomware campaigns

Ransomware attacks delivered via email are among the most destructive. These emails often contain malicious links or attachments that, when opened, activate ransomware. Once executed, the ransomware encrypts the victim's files or locks their device, demanding a ransom—usually in cryptocurrency—in exchange for restoring access.

For example, in 2021, Colonial Pipeline fell victim to a ransomware attack initiated by a malicious email. The attack forced the company to shut down its operations, resulting in widespread fuel shortages across the U.S. and a $4.4 million ransom payment. Such attacks highlight how a single malicious email can have far-reaching consequences for organizations and individuals.

Scams

Scam emails come in various forms and are crafted to deceive recipients for financial gain. Common examples include emails promising enticing rewards, such as lottery winnings or unexpected inheritances, which trick recipients into sharing personal or financial information or paying upfront fees to claim their "prize."

Other scams play on emotions. For instance, romance scams involve attackers building a false sense of trust and emotional connection with victims. Once trust is established, the attacker manipulates the victim into sending money for fabricated emergencies or personal needs. These scams often evolve over time, with attackers using psychological tactics to maximize their gains.

Spam

Spam emails flood users' inboxes with unsolicited advertisements, fraudulent offers, or irrelevant content. While spam may not always be malicious, it consumes valuable resources, clutters inboxes, and increases the risk of falling for phishing or malware-laden emails hidden among the junk.

How to secure your emails?

Use encryption

Email encryption protects the content of emails from unauthorized access or interception by encoding the message so that only the intended recipient can decipher it. It ensures that even if someone gains access to the email during transmission or stored on servers, they cannot read its contents without the appropriate decryption key.

• Transport Layer Security (TLS): TLS is a protocol that encrypts email messages in transit between email servers. It ensures that emails cannot be intercepted or read by unauthorized parties while transmitted over the internet. TLS is widely used and often implemented automatically by email service providers (like Gmail or Outlook).
• S/MIME (Secure/Multipurpose Internet Mail Extensions): S/MIME allows users to digitally sign and encrypt email messages using digital certificates, providing authentication and confidentiality. S/MIME is commonly used in enterprise environments and with email clients that support it, such as Microsoft Outlook.
• PGP (Pretty Good Privacy) PGP combines symmetric-key and public-key cryptography to encrypt and decrypt emails, files, or instant messages
• End-to-end Encryption (E2EE): E2EE encrypts messages on the sender's device and decrypts them on the recipient's device, ensuring only the sender and recipient can read the message. Encryption keys are stored locally, keeping them inaccessible to email service providers. Example: ProtonMail.
• Encrypted email gateways: These gateways encrypt emails as they leave an organization's network and decrypt them upon entering the recipient's network. This approach ensures secure transmission between organizational boundaries. Examples: Zix, Proofpoint.
• Cloud-Based Encryption Services: These services offer encryption as part of a cloud-based email solution, handling encryption automatically within the service infrastructure. An example is Google Workspace.

Implement Multifactor Authentication (MFA)

Multifactor Authentication adds an extra layer of security by requiring users to verify their identity through multiple factors, such as passwords, one-time codes, or biometric data. This reduces the risk of unauthorized access, even if credentials are compromised through phishing or other attacks. For example, a user logging into their email may need to enter a password and verify a code sent to their phone, ensuring enhanced security.

Configure DNS records

DNS (Domain Name System) records play a crucial role in email security by enabling various mechanisms that help protect email communication. Here's how DNS records contribute to email protection:

• SPF (Sender Policy Organization Framework): SPF is a DNS record that specifies that the recipient's mail servers are authorized to send emails on behalf of a domain. By publishing SPF records, the primary owners can prevent email spoofing and phishing attacks by specifying the legitimate email sources for their domain. When an email is received, the recipient's mail server checks the SPF record of the sender's domain to verify the authenticity of the sending server.
• DKIM (DomainKeys Identified Mail): DKIM is an email authentication mechanism that uses cryptographic signatures to verify the integrity and authenticity of messages. Domain owners generate a DKIM signature for outgoing emails by adding a DKIM record to their DNS settings. When an email is received, the recipient's mail server can verify the DKIM signature by looking up the corresponding DKIM record in the sender's DNS settings. DKIM helps prevent email tampering and ensures that emails are not altered during transit.
• DMARC (Domain-based Message Authentication, Reporting, and Conformance) DMARC is an email authentication protocol that builds up on SPF and DKIM to give domain owners greater visibility and control over their email traffic. With DMARC, domain owners can specify policies for handling emails that fail SPF or DKIM authentication, such as quarantining or rejecting them. DMARC also enables domain owners to receive reports on email activity, helping them monitor and improve their email security.
• PTR (Pointer) Records, or reverse DNS records, map IP addresses to domain names. Receiving mail servers use them to verify the sender's hostname's authenticity. When an email is received, the recipient's mail server can perform a reverse DNS lookup on the sender's IP address to retrieve the corresponding PTR record. A mismatch between the sender's hostname and the PTR record may indicate suspicious activity.

Use spam filters

Spam filters enhance email security by automatically identifying and blocking unwanted and potentially harmful emails. They detect phishing attempts, malware-laden attachments, and spoofed emails through content analysis, sender behavior, and reputation checks. Advanced techniques like machine learning and heuristics allow spam filters to recognize patterns and continuously adapt to emerging threats, preventing malicious emails from reaching users' inboxes.

Implement threat detection systems

Monitoring email activity and using threat detection tools is essential for spotting suspicious behavior and keeping emails secure. Behavioral analytics can detect unusual logins, like from unexpected locations or devices, which could signal a hacked account. Tools like Microsoft Defender scan incoming emails to flag and quarantine anything suspicious. They use machine learning to identify phishing attempts, malware, or spoofed emails based on known patterns. For example, if an email has a harmful attachment or comes from a risky sender, the system can block it before it reaches your inbox.

Best practices for email security

• Provide regular training and awareness programs to educate employees about phishing techniques.
• Configure spam filters on email servers or email clients to automatically detect and filter out spam, phishing, and malicious emails.
• Only click links or attachments if you fully trust them.
• Phishing emails often mimic real addresses. Look for misspellings or odd characters.
• Beware of files with extra extensions (e.g. ".pdf.exe").
• Use strong passwords and enable Multi-factor authentication for your email account.
• Keep email clients, web browsers, and operating systems up-to-date with the latest security patches and updates.