Re: [Libguestfs] [PATCH v3 0/7] Feature: Yara file scanning

NoxDaFox
2017-02-20T11:46:29Z

2017-02-20 12:26 GMT+02:00 Daniel P. Berrange <berrange@redhat.com>:

> On Sun, Feb 19, 2017 at 07:09:51PM +0200, Matteo Cafasso wrote:
> > Rebase patches on top of 1.35.25.
> >
> > No changes since last series.
>
> Can you explain the motivation behind adding the APis to libguestfs ?
>
> Since the libguestfs VM is separate from the real VM, it can't
> be relying on any live process state to scan for malicious code,
> so must be exclusively considering the file contents.
>

This is the use case. For the former one, there are tools such as Rekall
and Volatility which already do a great job.

http://www.rekall-forensic.com/
http://www.volatilityfoundation.org/


> Could yara not simply use the existing libguestfs APIs to do its
> work. At the simplest case this might be having the FS fuse mounted
> at a location. Alternatively having it directly use the C API to
> access content it needs would be safer against malicious symlinks.
>

There are both security and performance implication in using the FS fuse
locally mounted.

A vulnerability within the Yara scanner might lead to the host being
exposed. This is one of the reasons libguestfs is a good tool for helping
disk forensics as it adds a layer of protection against exploits.
More information here:
http://libguestfs.org/guestfs-security.1.html
https://pythonhosted.org/vminspect/#design-principles

Moreover, the fuse FS brings performance impacts which might be
considerable if we want to scan an entire FS or set of folders.
http://libguestfs.org/guestfs.3.html#mount-local


>
> Perhaps there's performance benefits todoing it by adding new APIs ?
> If so do you have any info on the scale of the benefit ?
>

> Regards,
> Daniel
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