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Date: Tue, 6 Aug 2013 19:33:18 +0300
From: Johan Boger <>
To: Trevor Bergeron <>
Subject: Re: Potential security flaw in network
 implementation at


It is possible this has now been fixed. I have talked with Digitalocean and
they have rolled out fixes in their network. I no longer observe the same
amount, just arp as you say. The problem was that their switches dropped
macs from the arp table, and the next packet was then sent onwards to all
other macs in that switch. This allowed you to see quite a bit.

If what you did no longer works, you did this after the fixes were rolled

I like how DO handled this, even though I disagree with how this was setup
in the first place. Arp spoofing might still be possible, but most likely
they will apply fixes for that too, in the following days.

All the best,

Johan Boger
On Mon, Aug 5, 2013 at 5:51 PM, Trevor Bergeron <> wrote:

> Would you mind sharing how you were getting other users' traffic? I am
> unable to replicate this, I see only STP and occasional ARP using
> # tcpdump -nni eth0 host not [my ip]
> mal
> On 08/04/2013 08:22 PM, Johan Boger wrote:
> > Hi,
> >
> > Today, I discovered that a certain large ISP specializing in cloud
> hosting (
> >, has misconfigured their network in a way that allows
> for
> > anyone to monitor customer network traffic. Per the guidelines of
> > responsible disclosure, I have informed the ISP in question both when I
> > first noticed the issue, and also before going public with the
> information.
> > As I am sure some of this info has already trickled out (or is perhaps
> > already common knowledge - if so, I apologize), I feel it is paramount to
> > get this information out there, so that customers and others who feel
> this
> > is not something they want, can act accordingly (or at least take
> > counter-measures to protect their information).
> >
> > What happened:
> >
> > I ordered a cloud vps (a very affordable one at that, I must say) at
> >, using the NYC node. During the process of checking
> > replication between master and slave, I noticed there was a lot of
> > background noise in tcpdump. I kept looking and when I eliminated the
> ports
> > I was using, what was left was somewhat worrying. It seems DigitalOcean
> > has, using KVM and libvirt per their own recognition, put the
> > libvirt-interface in an overly large bridge, and then kept applying more
> > and more networks (multiple /24, it seems). While this might be a
> > convenient way of assigning new networks to an ever-growing customer
> stock,
> > it also sort of turns the entire thing into an amateur radio station
> (using
> > the word amateur here to denote the activity, not the skill level of
> > Digitalocean staff!).
> >
> > I want to make one thing clear. This is one of the better cloud shops I
> > have used (and I have used a lot). They seem to have excellent support,
> > provide what they claim to provide, and my billing there so far amounts
> to
> > less than a dollar (even though I've fiddled with lots of stuff).
> > this does not mean that I want to be able to read what goes on with
> various
> > mail, ircd, web and Microsoft sql servers, in networks far outside of my
> > logical reach, as a customer with one IPv4.
> >
> > I am not an angry ex-customer. I will keep using their services, if this
> is
> > fixed. Which is exactly why I am sending this email. I hope that it might
> > add extra motivation, before someone gets their environment hacked. The
> way
> > it is now, anyone even remotely interested, could fire up a VPS in less
> > than a minute, and have full sniffing capabilities with hundreds (if not
> > thousands) of servers. All while customers are using said servers to
> > develop what I can only assume is important enough to host in a cloud.
> >
> > I will not paste logs as that would add nothing to my disclosure, more
> than
> > a possibility to exploit innocent users. I wish to encourage the
> community
> > to take a few steps back and not engage in target practice, while
> > Digitalocean undoubtedly remedies this situation (I have been in contact
> > with them repeatedly before coming here).
> >
> > I hope that this helps, for whatever it's worth. I will happily answer
> any
> > followups, as long as they do not include requests for additional probes.
> > This is where my involvement ends. I leave this information in the hands
> of
> > the community, and Digitalocean (who I hope reads this list).
> >
> >
> > Best Regards,
> >
> >
> >
> > _______________________________________________
> > Full-Disclosure - We believe in it.
> > Charter:
> > Hosted and sponsored by Secunia -
> >
> _______________________________________________
> Full-Disclosure - We believe in it.
> Charter:
> Hosted and sponsored by Secunia -

Johan Boger

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