New Active Exploit: memcached on port 11211 UDP & TCP being exploited for reflection attacks

Thu Mar 1 20:24:35 UTC 2018

On Thu, Mar 1, 2018 at 3:18 PM, Owen DeLong <owen at delong.com> wrote:

> I don’t agree that making RFC-1918 limitations a default in any daemon
> makes any
> sense whatsoever.
>
> First, there are plenty of LANs out there that don’t use RFC-1918.
>
> Second, RFC-1918 doesn’t apply to IPv6 at all, and (fortunately) hardly
> anyone
> uses ULA (the IPv6 analogue to RFC-1918).
>
> I do agree that listening on all addresses might not be the best default,
> but
> building assumptions about RFC-1918 into anything (other than the
> assumption
> that they’re generally a pretty bogus way to do IP) makes little sense to
> me.
>
>
this is sort of why openbsd listens only on 127.0.0.1/::1 by default,
right? it's the only sane choice for 'fresh out of the box' network
daemons: "Yes, it's running, yes I can healthcheck it locally to prove it's
running"

> Owen
>
> > On Mar 1, 2018, at 10:32 AM, Eric Kuhnke <eric.kuhnke at gmail.com> wrote:
> >
> > On the other side: VM/VPS providers have a template based image that they
> > use for every type and subtype of operating system it's possible to
> > auto-provision. For example Ubuntu Server Xenial AMD64 or Debian Jessie
> or
> > Stretch AMD64.
> >
> > It's important that VM/VPS providers don't push fresh images that have
> > anything vulnerable, abusable or exploitable enabled by default. Not all
> > VM/VPS providers do this. Standard sane configuration choices apply such
> as
> > bind9 not being a recursive resolver by default.
> >
> > If individual Debian, CentOS, Ubuntu or whatever other distro packages
> for
> > memcached or any other daemon have "listen on all interfaces = yes" or
> > "listen on non-RFC1918 IP ranges = yes" turned on in their respective
> > configurations, that would be an issue to take up with the package
> > maintainers for the daemons.
> >
> >
> >
> > On Wed, Feb 28, 2018 at 4:31 AM, Job Snijders <job at ntt.net> wrote:
> >
> >> Dear all,
> >>
> >> Before the group takes on the pitchforks and torches and travels down to
> >> the hosting providers' headquarters - let's take a step back and look at
> >> the root of this issue: the memcached software has failed both the
> >> Internet community and its own memcached users.
> >>
> >> It is INSANE that memcached is/was[1] shipping with default settings
> >> that make the daemon listen and respond on UDP on INADDR_ANY. Did nobody
> >> take notes during the protocol wars where we were fodder for all the
> >> CHARGEN & NTP ordnance?
> >>
> >> The memcached software shipped with a crazy default that required no
> >> authentication - allowing everyone to interact with the daemon. This is
> >> an incredibly risky proposition for memcached users from a
> >> confidentiality perspective; and on top of that the amplification factor
> >> is up to 15,000x. WHAT?!
> >>
> >> And this isn't even new information, open key/value stores have been a
> >> security research topic for a number of years, these folks reported that
> >> in the 2015/2016 time frame they observed more than 100,000 open
> >> memcached instances: https://aperture-labs.org/pdf/safeconf16.pdf
> >>
> >> Vendors need to ensure that a default installation of their software
> >> does not pose an immediate liability to the user itself and those around
> >> them. No software is deployed in a vacuum.
> >>
> >> A great example of how to approach things is the behavior of the
> >> PowerDNS DNS recursor: this recursor - out of the box - binds to only
> >> 127.0.0.1, and blocks queries from RFC 1918 space. An operator has to
> >> consciously perform multiple steps to make it into the danger zone.
> >> This is how things should be.
> >>
> >> Kind regards,
> >>
> >> Job
> >>
> >> [1]: https://github.com/memcached/memcached/commit/
> >> dbb7a8af90054bf4ef51f5814ef7ceb17d83d974
> >>
> >> ps. promiscuous defaults are bad, mmkay?
> >> Ask your BGP vendor for RFC 8212 support today! :-)
> >>
>
>