Re: [Qemu-devel] Design Decision for KVM based anti rootkit

[David Vrabel]

On 16/06/18 12:49, Ahmed Soliman wrote:
> 
> To wrap things up, the basic design will be a method for communication
> between host and guest is guest can request certain pages to be read
> only, and then host will force them to be read-only by guest until
> next guest reboot, then it will impossible for guest OS to have them
> as RW again. The choice of which pages to be set as read only is the
> guest's. So this way mixed pages can still be mixed with R/W content
> even if holds kernel code.

It's not clear how this increases security. What threats is this
protecting again?

As an attacker, modifying the sensitive pages (kernel text?) will
require either: a) altering the existing mappings for these (to make
them read-write or user-writable for example); or b) creating aliased
mappings with suitable permissions.

If the attacker can modify page tables in this way then it can also
bypass the suggested hypervisor's read-only protection by changing the
mappings to point to a unprotected page.

David