Periodic since 2.2 pages load blank, certs invalid

swix

When it happened, all dns requests returns "195.22.26.248" as IP address (also for invalid domains):

swix@pc:~> host google.ch
google.ch has address 195.22.26.248                                                                                                                                                                   
google.ch mail is handled by 10 mx1.csof.net.                                                                                                                                                         
google.ch mail is handled by 10 mx2.csof.net.                          

swix@pc:~> host aaaaaafadkfjdu93jifa.ch
aaaaaafadkfjdu93jifa.ch has address 195.22.26.248                                                                                                                                                  
aaaaaafadkfjdu93jifa.ch mail is handled by 10 mx1.csof.net.                                                                                                                                        
aaaaaafadkfjdu93jifa.ch mail is handled by 10 mx2.csof.net.

Unbound server is set as local resolver for a small LAN, with no forwarding to remote resolvers, so everything should be resolved locally.

Still investigating about how this could happen, and I will update this thread as soon as I find anything.
Kind regards.

PS: it apparently happened to last week, and I then disabled DNSSEC Support, but as it happened again it doesn't seem to be related.

Pakken

So far happened only one time for me.
After enabling dnssec and disabling all the forwards to public dns servers it seems to be fixed.
In addition, I've created a floating rule to block every local subnet to that 195.22.0.0 range.

Will keep you updated.
To be honest the strange thing is that in a couple of years of pfsense pre-2.2 and dnsmasq this never happened.
The problem appeared straight after upgrading to 2.2 and dnsresolver even tho, once again, only happened one time so far to me.

Best regards

doktornotor

@swix:

When it happened, all dns requests returns "195.22.26.248" as IP address (also for invalid domains):

I'd certainly investigate the LAN for possible infection. Just look at the amount of malicious crap associated with that IP:
https://www.virustotal.com/en/ip-address/195.22.26.248/information/

If you have some ISP-supplied router/modem in front of the pfSense box, Google for possible well-known firmware exploits as well.

@swix:

PS: it apparently happened to last week, and I then disabled DNSSEC Support, but as it happened again it doesn't seem to be related.

Disabling DNSSEC most certainly does NOT help anything. Very broken idea.

swix

@doktornotor:

I'd certainly investigate the LAN for possible infection. Just look at the amount of malicious crap associated with that IP:
https://www.virustotal.com/en/ip-address/195.22.26.248/information/
If you have some ISP-supplied router/modem in front of the pfSense box, Google for possible well-known firmware exploits as well.
ng DNSSEC most certainly does NOT help anything. Very broken idea.

Thanks for the suggestion, yes, I will try to have a look on this, but the network device (VDSL Bridge Zyxel P-870M) is in bridge mode, so I have no way to connect directly to it (or only via a serial console, with a cable to be found yet). Newest Firmware = 2009.

It just happened again a few minutes ago (3rd time today).

I was also trying to see if the root-servers file was tempered anyhow, but /etc/unbound/root.hints does not exist at all on the pfsense router.

Log extract when problem is happening, with many requests to "ns*.csof.net" servers where it shouldn't be the case :


Feb  9 12:55:25 pf unbound: [39509:0] info: reply from <4.85.in-addr.arpa.> 195.186.196.180#53
Feb  9 12:55:25 pf unbound: [39509:0] info: query response was ANSWER
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving daisy.ubuntu.com. A IN
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving ns1.canonical.com. AAAA IN
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving ns2.canonical.com. AAAA IN
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving ns3.canonical.com. AAAA IN
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving ns2.canonical.com. A IN
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving ns3.canonical.com. A IN
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving ns1.csof.net. AAAA IN       
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving ns2.csof.net. AAAA IN  
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving ns3.csof.net. AAAA IN
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving ns4.csof.net. AAAA IN
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving ns1.canonical.com. A IN
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving ns3.csof.net. AAAA IN
Feb  9 12:55:28 pf unbound: [39509:0] info: resolving ns1.csof.net. AAAA IN
Feb  9 12:55:28 pf unbound: [39509:0] info: response for ns3.canonical.com. A IN
Feb  9 12:55:28 pf unbound: [39509:0] info: reply from <com.>54.77.72.254#53
Feb  9 12:55:28 pf unbound: [39509:0] info: query response was ANSWER
Feb  9 12:55:28 pf unbound: [39509:0] info: response for ns2.canonical.com. A IN
Feb  9 12:55:28 pf unbound: [39509:0] info: reply from <com.>54.77.72.254#53
Feb  9 12:55:28 pf unbound: [39509:0] info: query response was ANSWER
Feb  9 12:55:28 pf unbound: [39509:0] info: response for ns1.canonical.com. A IN
Feb  9 12:55:28 pf unbound: [39509:0] info: reply from <com.>54.77.72.254#53
Feb  9 12:55:28 pf unbound: [39509:0] info: query response was ANSWER
Feb  9 12:55:28 pf unbound: [39509:0] info: response for daisy.ubuntu.com. A IN
Feb  9 12:55:28 pf unbound: [39509:0] info: reply from <ubuntu.com.>195.22.26.248#53          ########## wrong ! 
Feb  9 12:55:28 pf unbound: [39509:0] info: query response was ANSWER</ubuntu.com.></com.></com.></com.>

TBC.

Trel

I just want to clear up a few things

When any DNS Server can be used (not just unbound) and DNS Sec is set to off
-A DNS lookup from any computer to one of the domains cause EVERY subsequent lookup to resolve to "195.22.26.248"
(persists until unbound service is restarted)

When only unbound can be used and DNS Sec is set to ON, and port 53 is blocked except to pfsense
-A DNS lookup from any computer to one of the domains causes unbound to stop resolving anything, all lookups fail
(persists until unbound service is restarted)

Thanks to a packet capture I was able to find which domains were being looked up, I then overrode the hosts and set the IP to 0.0.0.0 so they resolve but obviously can't get out

When only unbound can be used and DNS Sec is set to ON, port 53 is blocked except to pfsense, AND the hosts are overrode so Unbound doesn't make any query on those domains outward either
-All problems seem to cease

(Also, due to the packet capture, I can say the original request is coming from an unrooted Android device requesting port 80 on a few of those sites, based on the URL, it's requesting an API for determining the outward IP)

EDIT: here's the overrides I did to flat out prevent those names from being resolved.

overrides.jpg_thumb

swix

Thanks for your update Trel, we're still searching here, but enabling DNSSEC does not stop the issue. And last time, it stopped by itself after about 5 minutes.

When "broken", all webrequests are redirected to http://xsso.www.example.org (with the original domain name instead of example.org).

GET /domain/www.example.org HTTP/1.1
Host: sso.mlwr.io
User-Agent: Mozilla/5.0 (X11; Linux x86_64) (...)
Accept-Encoding: gzip, deflate, sdch
Accept-Language: de,en-US;q=0.8,en;q=0.6
Cookie: anbsso=a5f4221ae2729d945150c83748e2ea12 (...)

Response: HTTP/1.1 302 Moved Temporarily
Server: nginx-perl/1.2.9.7
Date: Mon, 09 Feb 2015 14:29:31 GMT
Content-Type: text/html
Transfer-Encoding: chunked Connection: keep-alive
Set-Cookie: btst=b1b2035cffe818d92d7f6604a1318beb|myip|...
Location: http://xsso.www.example.org/a5f4221ae2729d945150c83748e2ea12

Just increased the logfiles size to try to see more next time it happens and added monitoring to get an alert directly.

And another view with wget, with and without https, with the same "lolcat" I already saw in another thread:


om@ompc:~> wget http://www.example.org
--2015-02-09 13:55:37--  http://www.example.org                                                                                                                                                     
Resolving www.example.org (www.example.org)... 195.22.26.248                                                                                                                                           
Connecting to www.example.org (www.example.org)|195.22.26.248|:80... connected.                                                                                                                        
HTTP request sent, awaiting response... 302 Moved Temporarily                                                                                                                                      
Location: http://sso.mlwr.io/domain/www.example.org [following]                                                                                                                                      
--2015-02-09 13:55:39--  http://sso.mlwr.io/domain/www.example.org
Resolving sso.mlwr.io (sso.mlwr.io)... 195.22.26.248
Reusing existing connection to www.example.org:80.
HTTP request sent, awaiting response... 200 OK
Cookie coming from sso.mlwr.io attempted to set domain to example.org
Length: unspecified [text/html]
Saving to: ‘index.html.3’

om@ompc:~> wget https://www.example.org
--2015-02-09 13:55:43--  https://www.example.org/
Resolving www.example.org (www.example.org)... 195.22.26.248
Connecting to www.example.org (www.example.org)|195.22.26.248|:443... connected.
ERROR: cannot verify www.example.org's certificate, issued by ‘/CN=lolcat’:
  Self-signed certificate encountered.
    ERROR: certificate common name ‘lolcat’ doesn't match requested host name ‘www.example.org’.
To connect to www.example.org insecurely, use `--no-check-certificate'.

Trel

You said you enabled DNSSEC, but question, what do you have in

System -> General -> DNS servers?

swix

PS: installed packages on this router: arpwatch, bandwithd, cron, darkstat, mailreport, nrpe, rrd summary, openvpn client export.

swix

@Trel:

You said you enabled DNSSEC, but question, what do you have in
System -> General -> DNS servers?

Completely empty, so shoud unbound start with root servers directly. I was wondering where was the hints file for unbound, but it seems to be directly in the binary file (strings unbound) :

A.ROOT-SERVERS.NET.
198.41.0.4
B.ROOT-SERVERS.NET.
192.228.79.201
C.ROOT-SERVERS.NET.
192.33.4.12
D.ROOT-SERVERS.NET.
199.7.91.13
E.ROOT-SERVERS.NET.
192.203.230.10
F.ROOT-SERVERS.NET.
192.5.5.241
G.ROOT-SERVERS.NET.
192.112.36.4
H.ROOT-SERVERS.NET.
128.63.2.53
I.ROOT-SERVERS.NET.
192.36.148.17
J.ROOT-SERVERS.NET.
192.58.128.30
K.ROOT-SERVERS.NET.
193.0.14.129
L.ROOT-SERVERS.NET.
199.7.83.42

Derelict

Ok. So what are the DNS servers configured on the client?

swix

@Derelict:

Ok. So what are the DNS servers configured on the client?

Set via DHCP, simply the router's ip address:


   option domain-name-servers 192.168.1.100;

Derelict

And you've actually verified that's the case on the client?

doktornotor

@swix:

Thanks for your update Trel, we're still searching here, but enabling DNSSEC does not stop the issue.

It does NOT stop the issue on domains that are not signed, no. Also, it will NOT prevent the DNS hijack if your clients are NOT using pfSense or another DNSSEC-enabled resolver, even if the zones are signed. It will prevent resolving domains to malicious crap for the rest.

Block/redirect all DNS queries on LAN to pfSense
Find and reimage infected crap.

Trel

@doktornotor:

Find and reimage infected crap.

I agree, but I would like to point out the way it affects pfsense/unbound is not a good thing at all.

A lookup on a completely isolated network segment made unbound start giving bad resolutions to ALL network segments when other DNS servers were permitted, and when they were blocked, unbound simply stopped replying.

That's not really the best outcome for a single computer looking up a bad domain.

swix

@Derelict:

And you've actually verified that's the case on the client?

Yes, + also did tests with dig @192.168.1.100 and directly via the pfsense shell. "poisoned" ip in every case (after a few seconds after the beginning of a new occurence of the issue).

@doktornotor:

It does NOT stop the issue on domains that are not signed, no. Also, it will NOT prevent the DNS hijack if your clients are NOT using pfSense or another DNSSEC-enabled resolver, even if the zones are signed. It will prevent resolving domains to malicious crap for the rest.

Yep, I supposed that too, but sometimes there are collateral effets to such settings.

@doktornotor:

Block/redirect all DNS queries on LAN to pfSense

Find and reimage infected crap.

It will continue tomorrow, now it is calm again, as everybody left the office :) But even if it is related to one malicious host on the LAN, it shouldn't be able to break the unbound resolver so easily…

Thanks again for all your feedbacks and until tomorrow!

Derelict

If pfSense/unbound asks the configured upstream DNS servers to resolve a query and gets something unexpected back it's not the fault of pfSense/unbound.

You need to be looking at these queries from the root back and see where things go wrong.

Very intriguing.

doktornotor

@Derelict:

If pfSense/unbound asks the configured upstream DNS servers to resolve a query and gets something unexpected back it's not the fault of pfSense/unbound.

Yes, exactly. Strongly suspect most of the people here are either using some hacked ISP device that hijacks the DNS traffic or the clients do not query the pfSense DNS resolver at all.

Derelict

Also, by obfuscating everything to example.com, you are eliminating the ability of everyone reading this thread from seeing what responses they get to the same queries.

Maybe someone else would get the BS responses and be in a better position to troubleshoot it than you are.

I would put this on LAN:

pass IPv4 TCP/UDP source LAN net dest ! 192.168.1.100 port 53 log

Put that above your normal pass rule. If everything is as you say, it should log nothing.

On pfSense 2.2 you should be able to set the dest to ! This Firewall (self).

doktornotor

@Derelict:

Also, by obfuscating everything to example.com, you are eliminating the ability of everyone reading this thread from seeing what responses they get to the same queries.

Pretty sure I could get these guys involved in investigating the issue here (they've also written the Knot DNS server so I'm rather convinced they are familiar with DNS :P) – however that'd require either remote access or at least uncensored traffic captures. Not example.com -- totally useless.

Trel

@doktornotor:

@Derelict:

If pfSense/unbound asks the configured upstream DNS servers to resolve a query and gets something unexpected back it's not the fault of pfSense/unbound.

Yes, exactly. Strongly suspect most of the people here are either using some hacked ISP device that hijacks the DNS traffic or the clients do not query the pfSense DNS resolver at all.

Using Comcast with a modem only (not a gateway in bridged mode). Here's the block rule.
With these settings, if I try to look up the domain I get this scenario

When only unbound can be used and DNS Sec is set to ON, and port 53 is blocked except to pfsense
-A DNS lookup from any computer to one of the domains causes unbound to stop resolving anything, all lookups fail
(persists until unbound service is restarted)

I understand that an infected machine should not be on the network, but if a mere typical DNS lookup can cause this much havoc, then something is really wrong.

restricted_dns.gif_thumb