With VirtualBox Guest Additions, "arbitrary string data" can be exchanged between guest and host

Given all the talk about using VirtualBox for privacy and security, it's worth emphasizing the risk of installing Guest Additions. In Chapter 4 ("Guest Additions") of the Oracle VM VirtualBox® User Manual <https://www.virtualbox.org/manual/ch04.html> under subsection 4.1 ("Introduction"), we see:

In Section 4.6. ("Guest properties"), we see:

Although software on the host and guest can exchange "arbitrary string data" using this "private communication channel", that's arguably not immediately problematic unless such software is present. Guests (VMs) are already at the mercy of their hosts, and this is just one of the mechanisms. The major threat here, I think, is that exploits in VMs could snoop on, or even compromise, hosts via existing host components. That's especially troubling for closed-source host operating systems, which could include "hooks" for VM exploits. Such "hooks" could also be spread via malware, of course.

 

Good post. I still don't know of an actual example where malware "in the real world" has broken out of a VM and made it to the host. Your thread title is very heart felt for me. I have been reading and hoping to find a way to safely use guest additions, but I always shrink back just suspecting its a security problem. As you know, I use many VM's for surfing the web. My biggest issue with VM's is screen resolution. I have discovered several ways to enlarge that but they all require guest additions.

I am struggling for a solution, but at the same time trying to avoid guest additions. I don't want to spend my days looking at a "half size" screen and I don't like the stretch look. I just want a more full size screen. Any ideas?

 

Well, scaled mode works without them, but it degrades resolution somewhat, which makes some desktops (particularly KDE for some reason) rather fuzzy So you're sometimes stuck between tiny and fuzzy

 

Yeah I tried Windows 7 on VirtualBox with guest additions. Without it, it looked awful. I wouldn't be able to use it much without guest additions. But it was pretty cool that I could run Windows 7 on a VM full screen and install Shadow Defender and Sandboxie and my VPNs etc. So my host had Shadow Defender and so did my VM. I enjoyed it. I'm ready to try Ubuntu now.

 

@caspian

Cool

 

I know we are only two of the many that hate the small screen size limitation of a VM. So for me its back to decision time. I will not run a small screen day in and day out, except for those operations where absolute security is a must. e.g. - here at Wilder's its a privacy issue for me but not really a strong security need. Since my host is Linux and never sees the internet except for updating itself, I feel OK with using a VM "adapted" for the convenience of a screen that is easy on the eyes. The host is still locked to VPN1 via UFW rules, so how can any leaks (not proven to have ever happened) be worse than those simply running Linux bare metal with a solid firewall in play? In other words an additional Linux VM running and using guest additions has to be at least as solid as Linux bare metal. Arguably it is much more solid since the VM "fear" of a breakout has never been proven in the real world. If I am incorrect on this PLEASE somebody throw up a real world link for us to review.

A side convenience is this allows the host to stay super clean, and swapping to a clean cloned VM every day or so takes about 3 minutes. This will simplify my backup protocol because the host is virtually static and maintaining a clean VM couldn't be any easier.

 

Sometimes I do install guest additions, for better performance, larger windows and shared folders. But like Palancar, that's on a Linux host with VPN and firewall, which isn't used for anything else, with FDE storage. But I don't install guest additions on Whonix, unless I'm doing something totally non-critical. And I always use Tor through at least two nested/chained VPNs.

 

Are you sure you are not my long lost brother/sister LOL!! During weak moments I use TOR with only one VPN in front of it. Forgive me? Joking!!!!

 

Joking aside, the fact that I use Tor is fairly high on my list of things that I keep private. While that's totally opposite to Tor Project's party line, posts on tor-talk like "OMG, I'm running a middle relay, and now my IP is banned!" are all too common

 

Seriously, I do know their party line. My ISP will never find out that I even know what TOR is, at least that is my goal. I never mention TOR in my extended family gatherings or other events, and of course would not dream of using TOR to connect to my real ID.

 

Well, one of their core goals is having everyone using Tor, so everything's private and no one stands out.

At least some PGP and now GnuPG advocates argue similarly about message encryption.

But hey, HTTPS is well on the way to becoming the norm

 

I don't even have my PGP key on a server. I simply distribute it as needed to those I wish to exchange stuff with.

BTW --- TOR is scooting along today.