Understanding Calendar-Based Phishing -

I felt compelled to write this blog post after getting three bogus events invite this weekend, and not knowing who had invited me! Unlike traditional phishing emails, calendar-based phishing involves unsolicited event invitations that automatically appear in a user’s calendar. These events often contain malicious links or prompts designed to harvest personal data. The invites I got contained links to a Google drive (probably to a script to hack my devices or Google account) or linking to a form to ask you to enter your details and steal your identity.

Common Tactics Employed

Fake Prize Notifications: Invitations claim the recipient has won a prize, such as a smartphone or gift card, requiring them to click a link to claim it.
Credential Verification Requests: Events masquerade as security alerts from trusted services, urging users to verify account details via provided links.
Urgent Action Demands: Invitations labeled as “Important” or “Urgent” press users to take immediate action, often leading to phishing sites.

Real-World Implications

Recent studies have highlighted the scale of this threat. For instance, researchers observed over 4,000 phishing emails exploiting calendar invites in a single month, targeting users across various sectors . Calendar-based phishing attacks often bypass traditional email security measures, as the invitations originate from legitimate calendar services.

Protecting Yourself from Calendar Phishing

Adjust Calendar Settings

To mitigate unsolicited calendar invitations:

Modify Invitation Settings:
- Navigate to your calendar application’s settings.
- Locate the option for Event Settings.
- Find the option related to Guest Permissions.
- Choose “Add Invitations to my Calendar – When I respond to the invitation in email” in the drop-down list to prevent automatic additions. It will effectively add an invitation to your calendar only when you respond to the invitation by email.

Be Cautious with Unknown Invitations

Verify the Sender: Ensure the invitation is from a known contact.
Avoid Clicking Suspicious Links: If unsure about an event’s legitimacy, refrain from interacting with its content.

Enhance Overall Security

Enable Two-Factor Authentication (2FA): Adds an extra layer of security to your accounts.
Keep Software Updated: Regularly update your calendar and email applications to patch security vulnerabilities.

Conclusion

Calendar-based phishing represents a sophisticated evolution in cyber threats, leveraging trusted platforms to deceive users. By staying informed and adjusting your calendar settings, you can significantly reduce the risk of falling victim to such scams.