Is it possible to write protect a CF card by hardware?

[sam1275]

Hi everyone.
Is it possible to write protect a CF card by hardware? Just like block pin23 (write signal) on IDEs, Is there any similar thing to completely block any writes on CF card? Some CF cards have write protection switch, is that reliable? Or just a dummy thing like SD cards.
Thank you.

[Grapsus]

The write signal is for writing an ATA command to the drive, it does not necessarily mean that data will be written on the disk. Hardware write blockers exist, they are used in forensics, but they're more complex than just blocking one pin, they need to understand the higher level protocol in order to refuse actual write commands.

[Fraser]

+1 on forensic write blocks.
Encase use such.
They are expensive but essential in legal forensics

Aurora

[sam1275]

Thank you guys!
So the block pin method even doesn't work on IDE?
What about the switch on the industrial CF card? Is there a way to bypass it without hardware access, for hackers or virus?

[Grapsus]

I think it's very hard to tell in general. There are many ways to implement a write protection in a memory card, it could be at IDE interface level, write access to flash chips could be blocked, etc. Depending on the attacker's level of access, remote administrator or physical access to the card, and the implementation of the protection it could be very easy or very hard to bypass.

Most importantly it will be very hard to get any level of warranty outside marketing crap. If what you're trying to protect has legal implications, you may better find an alternative solution like for example using robust cryptography to sign the data on the card instead of relying on the hardware.

[sam1275]

I think it's very hard to tell in general. There are many ways to implement a write protection in a memory card, it could be at IDE interface level, write access to flash chips could be blocked, etc. Depending on the attacker's level of access, remote administrator or physical access to the card, and the implementation of the protection it could be very easy or very hard to bypass.

Most importantly it will be very hard to get any level of warranty outside marketing crap. If what you're trying to protect has legal implications, you may better find an alternative solution like for example using robust cryptography to sign the data on the card instead of relying on the hardware.

Thank you.