Public Wi-Fi as a cyber risk: How to protect yourself from attacks while on the go

Public Wi-Fi hotspots are now standard in train stations, cafes, hotels, and airports. What many underestimate is that carelessly connecting to an open network risks the loss of sensitive data – from passwords to business-critical information.

The risk is particularly high for professionals who travel regularly or work from home, as mobile devices are usually not as secure as stationary workstations in the company.

The five biggest dangers of using public Wi-Fi networks

Man-in-the-middle (MITM) attacks involve cybercriminals secretly intercepting data between a user's device and their Wi-Fi router, allowing them to read sensitive information – from logins and emails to business documents. According to BSI reports, MITM is one of the most common attack methods in public spaces.
Spread of malware: Once connected, attackers can introduce malware such as ransomware or keyloggers. The consequences: data theft, identity theft, or complete compromise of the endpoint.
Using unencrypted networks: Many public Wi-Fi networks are inadequately secured or use outdated encryption technologies. Without current encryption (e.g., WPA3), it is easy for third parties to intercept all data traffic.
Fake network names (Evil Twin Attacks): Cybercriminals set up deceptively realistic Wi-Fi access points, for example with the name "Hotel_WiFi_Guest". Users accidentally connect to the wrong network – and directly expose their data.
WLAN sniffing and tracking: Using tools like Wireshark or hardware sniffers, attackers record network activities – including password entries, visited websites, or even access to internal tools.

Case study: Data leak through "hotel Wi-Fi"

A field service employee of an IT systems house used an open hotel network while abroad. His device unknowingly connected to a fake Wi-Fi network. Within minutes, customer data, emails, and CRM access credentials were compromised. The attack was only detected and stopped through analysis using Allgeier CyRis's Active Cyber Defense Service .

Seven measures for greater security in public Wi-Fi

Use a VPN : A Virtual Private Network (VPN) encrypts all data traffic and reliably protects against man-in-the-middle attacks. Many companies already provide their employees with VPN clients – these should be used consistently.
Enforce HTTPS connections : Always use encrypted websites ("https://") – many browsers offer add-ons that automatically block insecure connections. Emails should be retrieved via SSL-encrypted connections.
Disable file sharing : Block file sharing on mobile devices on public networks. On Windows and macOS, this can be adjusted in the network settings (select "public network").
Disable automatic network login : Don't let your devices automatically select known networks – criminals can deliberately imitate these. This option can be disabled in your system's Wi-Fi settings.
Avoid confidential activities : Refrain from online banking, password changes, or accessing internal systems while connected to a public Wi-Fi network.
Turn off Wi-Fi and Bluetooth when not in use : Even when inactive, many devices regularly exchange data with networks within range. Deactivate both interfaces when no connection is needed.
Think Zero Trust – even on mobile: Don't trust any network across the board – not even in business lounges or hotels. Zero Trust means: Every connection and every device is consistently checked before access is allowed.

Technical solution: Mobile security with EMILY from Allgeier CyRis

With its EMILY solution, Allgeier CyRis offers a centrally managed platform for secure mobile data access. EMILY combines secure VPN tunnels, granular access control, and device management. Companies can define policies to control or automatically block access to public Wi-Fi networks.

Real-time monitoring and device compliance allow you to define which applications are permitted to be active on public Wi-Fi networks – and which are blocked. This protects data, even when employees rely on unfamiliar networks while traveling.

Checklist: How to make public Wi-Fi networks safer

Activate a secure VPN tunnel for all mobile devices
Enforce HTTPS and SSL connections in browsers and email clients.
Disable automatic Wi-Fi connections and file sharing.
Avoid confidential actions on public Wi-Fi (logins, banking).
Use mobile security solutions like EMILY for network and access control.
Train your employees in the safe use of public Wi-Fi networks.
Conduct regular audits and security checks.

Conclusion: How to address public Wi-Fi networks with Zero Trust

Secure business communication doesn't end at the office desk – it must also be guaranteed on the go. Using public Wi-Fi is often unavoidable, but it must be done consciously and with the right security measures in place. Tools like VPN, EMILY , and a zero-trust strategy help protect sensitive data even on the most insecure networks.