Malware

What is Malware?

Malware is malicious software designed to infiltrate, damage, or gain unauthorized access to computer systems and data. In the context of email, attackers often use malware as a payload delivered via attachments, links to infected websites, or embedded scripts. Email remains one of the most common distribution channels for malware because it enables attackers to reach many targets quickly and to social-engineer recipients into executing harmful content.

Malware delivered by email can range from relatively simple annoyances to highly destructive tools. Examples include ransomware that encrypts files and demands payment, banking trojans that steal credentials, spyware that records user activity, and remote-access trojans that give attackers control over a compromised host. Attackers frequently combine malware with phishing techniques to increase the likelihood that recipients will open attachments or click links.

How Email Malware Works

Email-based malware campaigns typically follow a sequence of reconnaissance, delivery, and execution. Attackers craft messages that appear legitimate, using spoofed senders, lookalike domains, or compromised accounts, then attach malicious files (Office documents with macros, ZIP archives, executables) or include links to weaponized websites. If a user opens the attachment or follows the link and enables embedded content, the malware installs and begins its payload activities.

• Attachment-based payloads: documents or executables that run code when opened
• Link-based payloads: URLs to sites that host drive-by downloads or credential-phishing forms
• Macro-enabled files: Office documents that request macro activation to run malicious scripts
• Malicious archives: compressed files that attempt to bypass gateway scanners

Detection and Prevention Strategies

Defending against email-borne malware requires a combination of technical controls, policy, and user awareness. No single control is sufficient on its own, so layered defenses are the industry best practice.

• Publish and enforce SPF, DKIM, and DMARC to reduce the success of spoofed senders
• Use gateway antivirus, sandboxing, and URL scanning to detect malicious attachments and links
• Block or quarantine suspicious file types and require content-disarm/rewrap (CDR) for attachments
• Enable multi-factor authentication to limit damage from credential theft
• Keep endpoints and servers patched and use endpoint detection and response (EDR) tools
• Run regular phishing simulations and user training to reduce risky behavior
• Restrict macro execution and block or quarantine messages that request enabling macros

Rapid incident response and automated takedown processes for malicious domains and URLs reduce the attack surface and limit campaign duration. Monitoring telemetry, such as spikes in bounces, complaints, or unusual sending patterns, can provide early warning of active malware campaigns.

Malware and DMARCeye

DMARCeye helps organizations spot malware-related threats by correlating authentication failures, sending IPs, and message patterns across mailbox providers. While DMARC and related protocols do not detect malware directly, they reduce the effectiveness of impersonation techniques that attackers use to trick recipients into executing malware.

DMARCeye analyzes DMARC aggregate and forensic data to surface suspicious senders, lookalike domains, and compromised accounts that are commonly used in malware distribution. The platform also highlights abnormal volumes, unusual attachment types, and repeat offenders, enabling faster investigation and remediation.

Sign up for a free trial of DMARCeye today and secure your email domain.

To learn more about DMARC and DMARC-related terms, explore the DMARCeye Glossary.