How to spot malicious emails with ransomware

Did you know that many cyber incidents begin with a simple email? Ransomware attackers often use email as their first step to gain access to personal and business systems.

If you are reading this because you have experienced a ransomware incident and are unsure how to deal with it, contact Zensec immediately. Our rapid cyber incident response teams are available 24/7 to contain infected systems, protect your critical assets, and start the recovery process.

Unfortunately, many people aren’t familiar with these threats, meaning it’s challenging to distinguish between a safe message and a dangerous one.

The problem is that ransomware emails usually look similar to regular emails, and attackers use tricks to make the recipient believe that the message is from a person or brand they know and trust.

Even experienced users can slip up and open or click on an unsafe email. Luckily, there are ways to spot the signs of malicious emails, and we’ll cover them in this article.

What are malicious ransomware emails?

A malicious ransomware email is a phishing email designed to deliver ransomware malware. While typical phishing emails try to steal passwords or sensitive data, ransomware emails contain or link to a file that installs malware when they’re opened.

The malware encrypts files on the victim’s device and then demands payment for the decryption key.

Attackers often use attachments such as Word documents with hidden code or links that lead to infected websites. When the recipient interacts with these attachments or links, the ransomware begins its process, eventually locking critical files and systems.

These emails are crafted to look legitimate by copying the style and language of trusted contacts. The messages often include urgent requests to encourage quick action without careful thought.

• Invoice Scams: Fake invoices from companies you’ve never worked with

• Shipping Notifications: Delivery notices for packages you didn’t order

• Security Alerts: Warnings about account problems that don’t exist

• Document Requests: Urgent files that colleagues supposedly need you to review

Phishing emails are still popular because they target human psychology rather than technology. Email remains a popular delivery method because it allows attackers to quickly reach many people with little effort.

How ransomware emails differ from other threats

Not all suspicious emails work in the same way, and ransomware phishing emails have a specific goal: to deliver malware that locks files and demands payment. Other types of email threats focus on different objectives.

• Credential Phishing: The main goal of credential phishing is to steal personal information and login details. These emails lead to fake websites that look like real login pages. Ransomware emails focus on getting users to open files or click links that install malicious software rather than stealing passwords directly.

• Business Email Compromise: BEC scams don’t use malware at all. Instead, attackers impersonate executives or business partners to convince employees to send money or sensitive data through normal communication. These emails usually lack attachments or suspicious links because the goal is persuasion, not infection.

• Spam Emails: Spam emails are more generic in nature, and they’re often sent to thousands of people. In most cases, they send messages about shipping notices and invoices.

• Spear Phishing: Spam phishing impacts specific individuals with personalised details. Both types can deliver ransomware, but spear phishing appears more convincing because it includes real information about the target.

The key difference is that ransomware emails aim to compromise systems by running malware. Once ransomware executes, files can be encrypted quickly, and the damage can spread throughout connected networks.

Warning signs of ransomware emails

Most ransomware emails share specific characteristics that can help identify them before they cause harm:

• Urgent Language: The sender entices the recipient to act quickly, with subject lines like “Account suspended – verify immediately” or “Urgent payment required.” Legitimate organisations rarely demand immediate action without prior notice.

• Suspicious Addresses: Scam emails use domains that look similar to real companies. An email claiming to be from Microsoft might come from “microsft-support.com” instead of the official microsoft.com domain.

• Generic Greetings: Greetings like “Dear customer” or “Hello user” indicate mass-sent emails. Companies you have accounts with typically use your name in communications.

• Poor grammar and spelling can reveal non-native speakers or automated translation tools. Professional organisations proofread their communications carefully.

• Unexpected Attachments: If you’re not expecting the email provider to send an attachment, you should never click on it. These attachments include office documents, PDF files, compressed files, and files in unusual formats (ISO and OneNote).

• Context Problems: You should also check for emails that don’t match your situation, including invoices from companies you’ve never used, shipping notices for packages you didn’t order, or urgent requests from colleagues using unusual language, all warrant suspicion.

Multiple warning signs increase the likelihood that an email is malicious. When in doubt, verify through independent channels rather than responding to the email directly.

How ransomware email attacks work

Understanding the typical progression of an email-delivered ransomware attack helps with early recognition and response.

Initial delivery

The initial delivery phase begins when attackers send phishing emails to potential victims. These emails are designed to bypass spam filters and appear legitimate enough to avoid immediate suspicion. The message might impersonate a trusted sender or reference current events to seem relevant.

User interaction

If a user clicks on links or opens attachments, it counts as an interaction. This critical moment transforms a harmless email into a system compromise. Office documents might display messages like “Enable macros to view this document” to trick users into allowing malicious code to run.

Malware execution

If the user takes the bait, the malware activates. The initial payload might be a small program that downloads additional components or contacts remote servers for instructions.

Some attacks use a two-stage approach, in which the first program prepares the system before downloading the ransomware.

File encryption

Ransomware scrambles data using strong cryptography. Files become inaccessible and may be renamed with new extensions. A ransom note appears explaining that payment is required for decryption keys.

This entire process can unfold within minutes or hours of opening a malicious email. Early recognition at any stage can help limit damage, but prevention at the first stage is most effective.

Immediate response if you suspect a malicious email

If you suspect you’ve been sent an email with malicious content or phishing scams, taking instant action is essential. The time it takes you to react can be the difference between preventing phishing attacks from occurring altogether or minimising their damage.

If you receive a suspicious email but haven’t clicked on anything:

• Avoid interacting with any malicious links or attachments

• Verify the sender through independent contact methods

• Report the email to your IT team or security personnel

• Delete the message after reporting

If you’ve already clicked something suspicious:

• Disconnect from the internet immediately by unplugging Ethernet cables or disabling Wi-Fi

• Contact IT or security teams right away

• Preserve the original email and any error messages

• Avoid shutting down the computer unless files are actively being encrypted

• Change any passwords that might have been entered on suspicious websites

Speed matters more than perfection in these situations. Even if you’re not certain something is wrong, reporting potential incidents allows security teams to investigate and protect others from ransomware threats.

Prevention strategies

A multi-pronged approach is always best when protecting your company from malicious content and long-term damage. Popular techniques include:

• Email Security Systems: Email security systems offer spam filtering capabilities that filter dangerous messages before they reach inboxes. They scan attachments, check sender reputations, and analyse message content for suspicious patterns. Advanced solutions use sandboxing to test attachments in isolated environments.

• Software Updates: Regularly updating your computer systems’ software is key to plugging security holes that attackers might exploit. Keeping email clients, web browsers, and document viewers current reduces the chance that malicious files can execute successfully.

• User Training: Cyberattacks are a continuously evolving threat, and companies should focus on employee awareness. Larger organisations should educate team members on known vulnerabilities, including opening unrecognised emails and using weak passwords. Simulated phishing exercises provide safe practice opportunities.

• Account Restrictions: Only letting certain employees access information like bank accounts and customer details can make it harder for cybercriminals to disable your security systems and install system-wide malware.

• Backup Systems: Having a backup solution in place avoids the need to pay ransoms. Offline backups and immutable storage protect against encryption attacks. Recovery procedures help restore operations quickly after incidents.

Combining technical controls and human awareness creates multiple opportunities to stop attacks before they succeed.

Getting professional help

Organisations facing ransomware incidents often benefit from expert assistance. Incident response specialists bring experience, tools, and established procedures to complex situations.

Professional responders can quickly contain threats, analyse the scope of damage, and guide safe recovery processes. They understand legal requirements for breach notifications and can coordinate with law enforcement when appropriate.

ZenSec specialises in ransomware recovery and provides 24/7 support for organisations dealing with cyber incidents. Our team handles everything from initial containment through complete system restoration.

FAQs

What are the most obvious signs that an email contains ransomware?

Clear warning signs include unexpected attachments (especially Office documents asking you to enable macros), urgent language demanding immediate action, sender addresses that don’t match the claimed organisation, and requests to open files or click links for things you didn’t request.

Generic greetings like “Dear customer” instead of your name also indicate mass-sent phishing attempts.

How can I verify if a legitimate-looking email is actually safe?

Check the complete sender email address, not just the display name, for misspellings or wrong domains. Hover over links to see the real destination URL before clicking, and contact the supposed sender using official contact information from their website rather than replying to the email.

When in doubt, make phone calls to the organisation using their official numbers.

Can ransomware infect my computer just by opening an email?

Modern email programs don’t automatically run malicious code just from opening messages. Ransomware typically requires clicking a link or opening an attachment to activate.

However, avoid loading images or previewing attachments from suspicious emails, as some HTML content can still pose risks through techniques like HTML smuggling, resulting in infected computers.

Will antivirus software always catch phishing attacks?

Anti-virus programs and spam filters block many threats, but not all of them. Attackers constantly modify their techniques to avoid detection, and brand-new malware variants might not be recognised immediately.

Well-crafted spear phishing emails can bypass automated filters, making human vigilance essential as a final defence layer.

What immediate steps can prevent damage after clicking a suspicious email link?

Disconnect from the internet immediately by unplugging network cables or turning off Wi-Fi to prevent malware from communicating with remote servers. Contact your IT security team immediately and avoid shutting down your computer unless you see files actively being encrypted. Change any passwords you entered and preserve the original email for investigation.

Which types of email attachments pose the highest ransomware risk?

Office documents (Word, Excel, PowerPoint) with macros represent the biggest traditional threat, though Microsoft now blocks internet macros by default.

Attackers have shifted to OneNote files, HTML attachments, ISO disk images, and password-protected ZIP files to bypass security measures. Executable files (.exe) and script files (.js, .vbs) are inherently dangerous and rarely legitimate in business emails.

How do cybercriminals make ransomware emails bypass modern security features?

Attackers adapt to security improvements by using new file types not covered by existing filters, providing step-by-step instructions to bypass security warnings, or using social engineering to convince users to turn off protections.

They might send password-protected attachments with passwords in the email text, use legitimate file-sharing services to host malware, or exploit trust in newer formats like OneNote files.

Do cyber insurance policies typically cover ransomware attacks that start with email?

Most cyber insurance policies include ransomware coverage, but specific terms vary significantly between providers. Coverage might include incident response costs, business interruption losses, and sometimes ransom demands.

However, policies often require evidence of proper security practices, like employee training and updated software. Review your policy details and involve your insurer early in any incident for the best outcome.