Description |
This article describes downgrade issues due to an enhanced BIOS-level signature and file integrity checking. A solution is offered. |
Scope |
FortiGate running BIOS version 5000100, 6000100, or newer. |
Solution |
If a FortiGate device is running BIOS version 5000100 or 6000100 (or newer), the user will not be able to downgrade to 6.0, 6.2, or any other FortiOS versions below the ones listed here:
The device will not pass traffic and will display this error when booting up:
Booting OS...
It is recommend to upgrade FortiOS to a version that supports the BIOS security check to maximize the security posture of the device. Warning: Changing BIOS security level affects the overall security posture of the device and network. A lower BIOS security level could allow a user with administrative access to the FortiGate appliance to install and run modified, malicious firmware builds.
Note: It is possible to check the security level currently set before rebooting the unit or after changing it with the command 'get system status'.
get system status
Starting with v7.0.16, v7.2.11, v7.4.6, and v7.6.1, the naming convention for Security Levels has been updated. The previous numerical levels 0, 1, and 2 are now represented as low, low, and high, respectively. More information about this change can be seen in this document: BIOS security Low and High level classification 7.0.16.
Some units such as FortiGate 50G, 70G, 90G, 120G and 200G and their variants have a 'Signed Firmware Hardware Switch' that requires physical access to change the BIOS security level. If BIOS security level does not appear as an option for a physical device, see the product's datasheet to verify if a device includes this feature. |
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