[bshipp]

I don't know if I would say it's a nothing burger, but i don't see how it affects important servers. It might impact a number of linux desktops and, if they are linked to important servers, provide a backdoor access into important services.

Being able to run arbitrary code in a root account with no authentication would seem to be a pretty important security breach, although I don't think it's quite the level of danger it was built up to be.

[andersa]

But why would such desktops be exposed to the public internet directly?

[bshipp]

Likely no good reason. But he seemed to have identified many many systems that were, inexplicably, exposing port 631 to the internet. There is some reason people are doing it and, given the number of target systems, it must be some sort of default configuration.

  > "This thing is packaged for anything, in some cases it’s enabled by default, in others it’s not, go figure . Full disclosure, I’ve been scanning the entire public internet IPv4 ranges several times a day for weeks, sending the UDP packet and logging whatever connected back. And I’ve got back connections from hundreds of thousands of devices, with peaks of 200-300K concurrent devices. This file contains a list of the unique Linux systems affected. Note that everything that is not Linux has been filtered out. That is why I was getting increasingly alarmed during the last few weeks."

[bonzini]

The 9.9 issue is the foomatic-rip vulnerability; not cups-browsed listening on 0.0.0.0. See here:

> LAN: a local attacker can spoof zeroconf / mDNS / DNS-SD advertisements (we will talk more about this in the next writeup) and achieve the same code path leading to RCE.

[yrro]

I believe you'd still need cups-browsed installed, enabled & configured to accept remote printer broadcasts, _and_ have foomatic installed locally in order to get hit by this.

Modern version of cups will basically only talk to "driverless" IPP Everywhere printers, which all understand a common set of raster formats and hence have no need for printer-model specific software like foomatic-rip to be installed. They do this via mDNS, which means you don't need cups-browsed to be installed either.

[andersa]

I see. This sounds like a problem for people using public wifi...

[bonzini]

Maybe, maybe not. If I understand correctly, you still need to print something to the printer to achieve RCE via foomatic-rip.

[tsimionescu]

You do, until someone finds a way to exploit the other buffer overflows. But also, this attack is persistent: you get infected without any interaction at the coffee shop, and two years later when you print something at home on your well secured network: BAM!

[aragilar]

Uh, how? Unless somehow it stays around even though you've left the network (which I didn't think happens, but I could be wrong), this lasts just as long as the mDNS attacking server is on the network?

This to me feels like the author missed why the system was set up the way it was, and therefore doesn't present useful solutions.

[dumpsterdiver]

The likely target that emerged in my mind reading this is mom and pop point of sale systems.

The operators of such systems are completely oblivious to such risks, and the underpaid PoS software support team following a script to restart CUPS probably are as well.