[Cerowrt-devel] Possibly Serious Compromise

[Cerowrt-devel] Possibly Serious Compromise

[William Katsak]

I"m having a possible very serious issue with Cero. I started noticing 
slow internet access today and checked the router. I noticed a boatload 
of dns resolutions. These push the router load over 1, and eventually 
dnsmasq crashes and has to be restarted.

After tracing it for an hour or so and ruling out misbehaving software 
on the local net, I enabled logging in dnsmasq and saw that the 
resolutions were coming from 127.0.0.1. I kept running netstat -up until 
I saw some of the connections, and saw that they were coming from lua. 
All of the requests seem to be reverse DNS lookups of all kinds of crazy 
IPs.

These requests look like part of some attack/compromise. If I kill 
lighthttpd, everything settles down and runs fine. If I turn it back on, 
the traffic starts again. I am thinking some kind of vulnerability in 
the http server allowing malformed requests from outside? I can't for 
the life of me figure out how they are getting in though. I have very 
few changes to the firewall config, and only a few port forwards.

I'll send more info as I get it.

Anyone else see anything like this?

-Bill


-- 
****************************************
William Katsak <wkatsak@gmail.com>
****************************************

Re: [Cerowrt-devel] Possibly Serious Compromise

[Dave Taht]

Hmm. Port 81 is generally blocked from the outside world, which is
where lua runs. Port 80 is open, but serves up nearly no files by
default, and shouldn't be able to get to lua.

Please install tcpdump-mini. put in a usb stick and mount it. do a
tcpdump -i ge00 -w /whereverthestickis. Put the capture file up
somewhere I can get at it. Or just capture for 60 seconds to /tmp
(assuming little other traffic).You can also cut the size of the
capture down with -s 128, but that wouldn't reveal what was going on
as well.

I was, incidentally, under the impression we'd left reverse dns
lookups off in lighttpd.


On Sat, Jan 3, 2015 at 4:20 PM, William Katsak <wkatsak@gmail.com> wrote:
> I"m having a possible very serious issue with Cero. I started noticing slow
> internet access today and checked the router. I noticed a boatload of dns
> resolutions. These push the router load over 1, and eventually dnsmasq
> crashes and has to be restarted.
>
> After tracing it for an hour or so and ruling out misbehaving software on
> the local net, I enabled logging in dnsmasq and saw that the resolutions
> were coming from 127.0.0.1. I kept running netstat -up until I saw some of
> the connections, and saw that they were coming from lua. All of the requests
> seem to be reverse DNS lookups of all kinds of crazy IPs.
>
> These requests look like part of some attack/compromise. If I kill
> lighthttpd, everything settles down and runs fine. If I turn it back on, the
> traffic starts again. I am thinking some kind of vulnerability in the http
> server allowing malformed requests from outside? I can't for the life of me
> figure out how they are getting in though. I have very few changes to the
> firewall config, and only a few port forwards.
>
> I'll send more info as I get it.
>
> Anyone else see anything like this?
>
> -Bill
>
>
> --
> ****************************************
> William Katsak <wkatsak@gmail.com>
> ****************************************
> _______________________________________________
> Cerowrt-devel mailing list
> Cerowrt-devel@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/cerowrt-devel



-- 
Dave Täht

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