TL;DR
Yes, it’s possible, but difficult and unlikely for most attackers. A previous visitor could potentially install persistent spyware if they had physical access to your network (even briefly) and exploited vulnerabilities. However, modern operating systems and security measures make this challenging. Factory reset resistance adds another layer of complexity. Focus on strong passwords, up-to-date software, and monitoring for unusual activity.
Understanding the Threat
Let’s break down how an attacker might try to do this and what makes it hard:
- Initial Access: The attacker needs a way onto your network. This could be through compromised Wi-Fi, exploiting a vulnerable device (like an old router), or even physically connecting something to your network.
- Malware Installation: Once inside, they need to install malware on your PC and phone.
- Persistence: The biggest challenge is making the malware survive reboots and, crucially, factory resets. This requires deep system access and techniques like modifying bootloaders or firmware.
Steps to Protect Yourself
- Secure Your Router (First Priority):
- Change the Default Password: Use a strong, unique password.
- Enable WPA3 Encryption: If your devices support it, use WPA3 for stronger Wi-Fi security.
- Update Firmware Regularly: Router manufacturers release updates to fix vulnerabilities. Check their website or router settings.
# Example command (may vary by router) - Disable Remote Management: Unless you specifically need it, turn off remote access to your router’s settings.
- Keep Your Software Up-to-Date:
- Operating Systems (Windows, macOS, Android, iOS): Enable automatic updates or check for them regularly. Updates often include security patches.
- Applications: Update your browsers, antivirus software, and other programs.
- Strong Passwords & Multi-Factor Authentication (MFA):
- Use strong, unique passwords for all accounts. A password manager can help.
- Enable MFA whenever possible. This adds an extra layer of security beyond just a password.
- Antivirus/Anti-Malware Software:
- Install reputable antivirus software on your PC and phone. Keep it updated.
- Run regular scans.
- Firewall Protection:
- Ensure your firewall is enabled (Windows Firewall, macOS Firewall).
- Configure the firewall to block unwanted connections.
- Monitor Network Activity:
- Look for unusual traffic patterns. Your router’s interface might show connected devices and their activity.
- Consider using a network monitoring tool (e.g., Wireshark – advanced) to analyze traffic.
- Factory Reset as Last Resort:
- A factory reset will remove most malware, but it’s not foolproof if the attacker has deeply embedded themselves in firmware or bootloaders (rare).
- After a factory reset, immediately update your software and change passwords.
- Beware of Phishing & Social Engineering:
- Be cautious about clicking links or opening attachments from unknown sources.
- Don’t share sensitive information over email or phone unless you are certain of the recipient’s identity.
Factory Reset Resistance & Persistence
Spyware designed to survive factory resets is advanced and typically targets specific devices or vulnerabilities. It often involves:
- Bootloader Modification: Altering the code that runs before the operating system loads.
- Firmware Exploitation: Compromising the low-level software controlling hardware components.
- Secure Boot Bypass: Disabling security features designed to prevent unauthorized bootloaders from running.
These techniques are complex and require significant technical expertise. While not impossible, they’re beyond the capabilities of most attackers.
What if You Suspect Infection?
- Disconnect from the Network: Immediately isolate your devices to prevent further communication with the attacker.
- Run a Full System Scan: Use multiple antivirus/anti-malware programs.
- Consider Professional Help: If you’re concerned, consult a cyber security professional for assistance.
- Factory Reset (with caution): As a last resort, perform a factory reset after backing up important data (if safe to do so).