Switch Firmware v5.00: Enhanced Firmware Integrity Check

Zyxel_Claudia

To improve system security and prevent tampering, Zyxel Networks has implemented a new Enhanced Firmware Integrity Check mechanism in its latest switch firmware v5.00. This enhancement helps validate firmware authenticity using standardized cryptographic verification before installation or upgrade.

Why Firmware Integrity Matters

Firmware updates are critical to maintaining the security, stability, and feature set of your switches. However, corrupted or tampered firmware files can cause:

• Security breaches
• System instability

That’s why Zyxel now uses a SHA-256 hash-based integrity check to verify the authenticity of firmware files before they are applied.

Previous Behavior: Proprietary Hash Validation

In earlier firmware versions (before v5.00), Zyxel switches used a Zyxel-specific proprietary hash to verify firmware files.

What’s New in v5.00?

Firmware v5.00 introduces two integrity check methods:

1. Standard Integrity Check
   • Uses Zyxel’s proprietary hash (still supported for backward compatibility).
2. Enhanced Firmware Integrity Check (New)
   • Uses SHA-256, a widely adopted industry standard for secure hashing.
   • Verifies the firmware against an embedded SHA-256 checksum.

Default Behavior

When uploading firmware (v5.00 and later) via the Web GUI:

• The Enhanced Firmware Integrity Check is enabled by default.
• If the uploaded firmware lacks a valid SHA-256 checksum (e.g., older firmware versions), the system will reject the file and display an error.

Handling Downgrades

If you're attempting to downgrade to an older firmware version that does not include a SHA-256 hash:

• You must manually disable the Enhanced Firmware Integrity Check.
• This option is available under Maintenance > Firmware Upgrade in the Web GUI.

Once disabled, the system will revert to using the standard integrity check and allow installation of the older firmware.

Example Error

When trying to downgrade to a firmware version without a SHA-256 checksum while integrity check is enabled, you'll see error in the system log:

“Upgrade firmware failed due to file check error.”

Compatibility with External Tools

Regardless of whether you use:

• Web GUI
• FTP
• Zyxel’s ZON Utility

The firmware integrity check behavior will follow the switch's current configuration.