Taming the beasts… aka suricata blueprint

If non-transparent proxy is being used, there is no real point in running Snort or Suricata with blocking enabled on LAN interface - all connections will be between internal hosts and LAN interface IP where proxy is listening. By default, those are whitelisted and if you decide to block internal hosts, you will cut off them from the internet completely…

Are you talking about a transparent firewall running snort/suricata? There are uses for this, no it's not for everyone. By default snort/suricata has difficulty determining its IPs when running in transparent mode, so no hosts will be whitelisted. Ask yourself. What would you pick? System compromise or system getting cut off from the internet? If an internal server is infected somehow and starts spewing exploits here and there, the acceptable way of dealing with it is cutting off its network access. Care! There have been cases (supposedly) in the past where malware was (allegedly) designed to that if you pulled the ethernet cable it would start destroying the system's filesystem.

A transparent snort/suricata system comes in handy when you don't want hosts on the network being able to access it in any way. How will you attack the upstream gateway if you don't know there IS an upstream gateway?

dgcom

Hmm… I thought, I clearly wrote:

If non-transparent proxy is being used…

Let me try one more time - if you do NOT run proxy (Squid or anything else) in transparent mode - which means internal machine browser have to specify proxy in the browser, which, in turn, means that internal machine will connect to proxy in order to request any web page - in this case, running Snort/Suricata riles, which check any protocols, which proxy can rely (ex. HTTP, HTTPS, FTP) is possible in alert mode only. Even if you check to block, by default connections will not be blocked, because they are only between internal machine and LAN interface IP and those IPs are whitelisted by Snort/Suricata as internal network.

See example in the attached screenshot. In there, 192.168.15.56 is the internal IP of the pfSense, which has Snort listening on port 8080 and 192.168.15.174 is the client, receiving obfuscated JavaScript in the web response. Snort will not block this because all IPs are internal.

In this case, if such blocking is required, appropriate rules should be activated on WAN interface, but you will not see internal IP in the alerts.

Sample1.jpg_thumb

Transparent or not the proxy will still not be blocked, since it's a known IP by snort/suricata. (WAN interface).

It will block the external host though, as long as it can see inside the protocol (ie no TLS).

If you want to block internal hosts, then just change the pass list to a different one. Snort/suricata will think all systems are to be blocked (even internal IP ones) if you have it listening on an internal interface.

EDIT:brain fart :p

dgcom

Transparent or not the proxy will still not be blocked, since it's a known IP by snort/suricata. (WAN interface).

Sorry, not sure I understand you - do you have your proxy listening on WAN interface?

If you want to block internal hosts, then just change the pass list to a different one. Snort/suricata will think all systems are to be blocked (even internal IP ones) if you have it listening on an internal interface.

What is "it" in here? Proxy?

Entire internal network is in the pass list by default.

Snort/suricata WAN interface. No matter what proxy you run internally, eventually it must connect to the outside to pull data in. That's when the alerts will fire up. Snort/suricata will try to ban both source+destination (if you did not set it up like that, you should) and since the destination (proxy) is listed on its (snort/suricata's) pass list, it (proxy) will not be blocked. The outside IP will though.

WRT the listening, I was talking about snort/suricata.

"Entire internal network is in the pass list by default." I am aware of that, that's why I said change the pass list. If you tell suricata these are the networks you should NOT ban, but do NOT include the private IPs in that list, suricata will notice the alert, check to see if a private IP is on the pass list, NOT see the IP there, therefore will proceed to ban the internal IP. Most likely the proxy (pfsense) will be banned as well, so that IP should be on the pass list.

If I still fail to see the point, my apologies, it was a long day.

dgcom

Yeah, I think we speak different languages.

I am not talking about WAN interface, not sure why you brought it in.

I am talking about Snort/Suricata instance on LAN interface. In case of non-transparent proxy it does not see external IPs, period.

Cino

WAN is brought in because it is needed to connected to the outside world. If you have the same rules on both interfaces and an alert pops up; the WAN interface will block the the external IP. interface. Since you should have the same alert for both interfaces, you can cross reference the WAN/LAN alert logs to find the internal IP on your LAN interface. I get what you're saying now about the LAN not blocking the the internal IP since its already white-listed. I haven't had any LAN clients stumble any malicious javascript yet.

@dgcom:

Yeah, I think we speak different languages.

I am not talking about WAN interface, not sure why you brought it in.

I am talking about Snort/Suricata instance on LAN interface. In case of non-transparent proxy it does not see external IPs, period.

snort/suricata interface on LAN should show the same alert that snort/suricata on the WAN will show. If you did change the pass list, then both the internal (private) IP and the external (malicious site) IP will be blocked. If you still think that pfsense will not see the internal IP because it somehow "travels through the proxy" then you are missing a critical piece of information. snort/suricata are running the interfaces as promiscuous. That means they see every single packet that hits them, even if it's not destined for them. snort/suricata will see the packets from the laptop to the proxy (assuming proxy on pfsense), the proxy's answer to the laptop (both on LAN interface) and the request from the proxy to the malicious site, and the malicious site answer to the proxy (WAN interface). Anything that flags an alert with any of that will result in an IP being blocked, even internal IPs. Period. (throwing it in there, since something clicks in my head when someone says period to me, then everything turns black).

dgcom

@Cino:

If you have the same rules on both interfaces and an alert pops up; the WAN interface will block the the external IP. interface. Since you should have the same alert for both interfaces, you can cross reference the WAN/LAN alert logs to find the internal IP on your LAN interface. I get what you're saying now about the LAN not blocking the the internal IP since its already white-listed. I haven't had any LAN clients stumble any malicious javascript yet.

Yes, that is the point I am trying to make - in such case you have to have appropriate rules enabled on WAN interface and, as you said, there is a need to find which internal IP it was, on the LAN interface as well… But that is a lot of manual labor to cross-reference alert logs :( And the additional memory used for duplicate rules...

For me, Snort http preprocessor with its built-in inspection rules (like (http_inspect) HTTP RESPONSE HAS UTF CHARSET WHICH FAILED TO NORMALIZE) is too noisy and blocks normal sites often.

dgcom

@jflsakfja:

Anything that flags an alert with any of that will result in an IP being blocked, even internal IPs.

Don't know about you, but in my setup internal IPs are in the safe list by default (did I repeat it 3rd time?).
Oh, and I am not complaining about that.

@dgcom:

@jflsakfja:

Anything that flags an alert with any of that will result in an IP being blocked, even internal IPs.

Don't know about you, but in my setup internal IPs are in the safe list by default (did I repeat it 3rd time?).
Oh, and I am not complaining about that.

I also repeated 3 times that you can actually change the PASS list so they are not.

dgcom

And why would I need to remove my internal network from the pass list?
What is the use case? May be for some public hotspot it may make sense, but not for the trusted network…

There is no such thing as a trusted network. As I said somewhere else, the only thing you should trust is the little voice inside your head. Everything/everyone out there is out to get you. And no, it's not paranoia when they ARE out to get you.

NSA aside, the use case is when trying to limit a local (internal) host from spreading something nasty on the internet. Other than that, there is no use for it, since it can still spread the "nasty" to other hosts on its subnet. When each host is on a different subnet, that's a different story, it effectively blocks it from accessing the entire network, but that is a highly specialized use case (ie not something you will encounter outside of an ISP).

Another use case that pops into my mind is when providing internet access to others (free wifi anyone?). You can't tell what their systems are infected with, so to limit your liability you could block it from accessing the internet.

As you can see from the guide, most weight is put into securing the network from outside threats, with some weight given on somewhat limiting outgoing connections. My recommendation for a normal home network is to use your trusted network example. Perfectly normal paranoia aside, it's very unlikely the NSA has broken into your house/computer-while-it-was-shipped and installed a backdoor. Incoming "nasties" are blocked. Since they are blocked, and you use some common sense (a shocking truth, but that hottie that keeps sending you naked images of her, is actually trying to get your email client to parse a command obfuscated in the image, ala firefox (yes a browser) jpg code execution), your network is (mostly) safe. Yes there are other attack vectors (eg browser memory mismanagement) but those are outside the scope of this guide :D.

BBcan177

Here is a report from The Solutionary Security Engineering Research Team (SERT) Quarterly Threat Intelligence Report for Q2 2014

http://www.solutionary.com/research/threat-reports/quarterly-threat-reports/sert-threat-intelligence-q2-2014/

Key findings include:
The top 10 ISPs represented the source of 52% of the malware identified in the new period.

Amazon-hosted malware nearly triples in first half of 2014.

56% of malware captured was hosted in the United States, a 12% increase from Q4’13

Malicious SSH activity continues to be a popular method to gain administrative access to target systems.

Not going to register to download a report that I'm responsible of producing at my work :p

Let me guess, they propagate the Chinese 1337 hackers meme?

BBcan177

@jflsakfja:

Not going to register to download a report that I'm responsible of producing at my work :p
Let me guess, they propagate the Chinese 1337 hackers meme?

Its great that you are cataloging these Malicious Attempts in your network. But its important to have a well balanced Source of Threats. Some Sources are good for Mail Servers, others Malware, others SSH attack etc. By combing threat sources from a multitude of Threat Sources, you can better determine their IP Reputation.

I typically don't like to have to register for Reports also. But looking at the Solutionary Website, there are other reports available online without needing to register.

http://www.solutionary.com/research/threat-reports/monthly-threat-reports/2014/06/security-threat-report-june-2014/

Looking at my current suggested List of Blocklist Sources (See data below),

grep "98.124.198.1" pf/*

pf/ET_IPrep.txt:98.124.198.1
pf/e_tcnc:98.124.198.1
pf/e_tdrop:98.124.198.1

grep "85.159.211.119" pf/*

pf/ET_IPrep.txt:85.159.211.119
pf/e_tblackhole:85.159.211.119
pf/e_tcnc:85.159.211.119

grep "85.25.148.6" pf/*

pf/IBlock_BT_Spy.txt:85.25.148.6

grep "217.12.207.151" pf/*

pf/IBlock_BT_Spy.txt:217.12.207.151

grep "192.99.6.61" pf/*
no results
grep "192.99.6.0" pf/*
no results
grep "^192.99." pf/*
pf/ToastedSpam.txt:192.99.0.0/16

Game Over Zeus Botnet (goz)
http://garwarner.blogspot.ca/2014/07/new-gameover-zeus-variant-uses-fastflux.html?m=1

Only ET IQRisk Blocklist picks up all of these IPs.

I have seen this spam hit my Network "E-ZPass" (I forwarded them to SpamCop also)
http://garwarner.blogspot.ca/2014/07/e-zpass-spam-leads-to-location-aware.html?m=1

Only ET IQRisk Blocklist picks up all of these IPs.

Mr. Jingles

Right, I finally have a little bit more time to work on this now :P

Could I ask one more question, JFL?

This is what I am struggling with:
1. You said in one thread (I think it was your previous thread about how to set up Snort) said to ditch Snort for Suricata;
2. Some Snort rules (some 600 I believe Bill said) Suricata can not interpret.
3. Your current instructions (this thread) only deal with the ET-rules, not with the Snort rules.
4. I take it ET doesn't completely overlap the Snort (paid subscription, which is what I have) rules, so there is/might be value in using both the Suricata- and Snort rules in Suricata.

What would be wisdom here? Take your old instructions about the Snort rules to know what to disable, or do you consider these instructions obsolete perhaps? If so, ditch Snort all together? (but then point 4?) If not ditch Snort, how do you cope with the rules Suricata can't handle (the Snort rules)? There are 600 it seems, so [a1] how to find out which ones and [a2] after disabling these, aren't we missing out on important protection?

Or: have both Snort and Suricata inspect the interfaces at the same time (Snort with the full subscriber rule set, Suricata with the ET rule set)?

Yes, vague and complex for a stupid economist like me, I know :-[

( ;D )

Thank you again very much :P

@Hollander:
1)The only reason suricata is better than snort is that snort's inline has been abandoned and the developers moved to suricata, so if you want an IPS then you have to use suricata. We are talking about the general majority of users out there, there are other differences, but most users will never notice them. There is NO other software out there that matches its capabilities right now, pay,free,donated-to-us-by-aliens. It is actually the top of the line, absolute best IDS/IPS available. It bloody hell should be the best, it was funded directly by the U.S. government, I'm sure those guys want to get their money's worth.

2)As far as the rules that suricata cannot interpret you only have these 2 choices:a)don't use them or b)manually rewrite the rule so that it is accepted by suricata.

3)This thread is about suricata, so there is no point in dealing with the snort rules, since those rules are not used. My opinion as to whether they are updated, or not, is my opinion only and does not reflect the opinion of The Company, etc… etc...

4)If you followed the guide to the letter and actually set up your suricata as suggested, you should be seeing about 90% banned hosts from custom rules (simple port scanning rules that detect port scans even the ET rules miss). Do you want to focus on the 1% that is banned hosts from the snort rules (assuming you are using snort with suricata, and filtered out the not working rules), the 9% from ET rules, or the 90% from custom rules? ;)

The trick to setting up an IDS/IPS is thinking like an attacker. What would you do to compromise an unknown system? These are the steps (most) attackers worth their salt follow (note: Does NOT refer to Chinese and Korean so called "state sponsored hackers", I don't have the time to deal with script kiddies):
a) Identify who the system belongs to. If it belongs to a letter soup agency, have the drill ready (you do have a "In the case of emergency, drill HERE" sticker that when followed shatters the HDD's platters right? Easy access to RAM modules (cold attack) is a bonus.
b) Identify used services. Usually a full portscan follows that identifies the used ports. This is the first trap we set up. Following this guide, ALL privileged ports are now under constant check. A portscan (even so called "sophisticated" portscans, using actual TCP handshakes (not trying to trick the system into responding)) WILL hit our trap if it's destined for privileged ports (probability it is:infinite).
c) In the case of true "state sponsored hackers" I personally expect them NOT to perform portscans. They should have been at one of my classes so far (if you are a state sponsored hacker and have missed my training classes, please contact your supervisor for a re-schedule) and should have known by now than when attacking, you NEVER alert the victim. And yes, I am talking to you United States Army Information Systems Control (now integrated into NETCOM). How many times have you seen a cat running around screaming "ARE THERE ANY MICE HERE??????" It crawls silently next to its victim, then attacks. The same strategy should be implemented here: Perform a legitimate connection to a used port, and see what information you can gather from it. If it spews out that the webserver used is a known buggy version, then find the exploit for it and attack it. It's not rocket science. This is were security by obscurity comes in handy. If you don't allow the attacker to understand the version of a software used, then the attacker is more likely to screw up by trying to use known large scale exploitable bugs (bugs that should be corrected by your updates long ago. You are updating without delays right?). Suricata will fire up an alert on old exploits, since I will not bother with the latest and greatest exploits. If my upstream distribution patches the flaw within 8 hours of it being public, and ET publishes a rule update at the end of the day, I'll take my upstream distribution over ET any time. What I'm trying to say here is, there is no point in trying to keep up with exploits using rules, you should instead keep up with exploits using server admin best practices. 99.999% of so called "industry leaders" have absolutely NO idea when the last time their servers were updated. I've seen SSL certificates being expired for a WHOLE YEAR being used by a so called "leading web hosting provider", and I believe my, and everybody's, conclusion is that if you did not see that your SSL certificate has been expired for the past year, there is at least a 1 year gap between the last time you checked and updated the server and now. 1 year of NOT patching a system is the difference between a compromise and not.
d) The attacker has successfully exploited a known flaw and is now on your system. This is were inward facing interfaces come in handy. If a webserver starts scanning your firewall for open ports, then this is a clear sign of a compromised system. If that same webserver starts sending out reflection attacks out of nowhere, it too is a clear sign of a compromise. Ideally in this case the IDS/IPS will block the server. Having a few angry customers is better if you handle your compromise transparently. An announcement somewhere along the lines of "We have detected signs of a system compromise and have to shut down a system pending further investigation" will go a long way instead of, I don't know, SITTING ON A COMPROMISE FOR 2 MONTHS? coughebaycough pardon my Vogons. Seeing your webserver ending up on your IDS/IPS's banned hosts list is your hint to pick up the phone, give me a call and say "hello, are you offering forensic analysis services? Yes, we have had a system compromise. Ok I'll see you on monday". You should never ask how much a forensic analysis of a compromised host costs. It's a case of a "if you have to ask how much it costs, you cannot afford it".

Summary because I just previewed the post and my $deity I write long posts :p.
Use the IDS/IPS to detect and prevent network attacks. Use server best practices to STOP host attacks. If you are using snort/suricata for a home network, most of these points are invalid, since the only way in is:
1)browser bug
2)email client bug
3)irc/messenger/voip client bug
4)"any service that performs connections with a remote network" bug

Trust me, if I can't see it, I can't shoot at it. Light bending around planets to look behind them (not the keep a google tab open type, if I can't type its name out of my head, I don't bother) does not apply in network/system security.
Ideally the bugs should be handled by your upstream (commercial company,beer drunk open source developers, depends on the case) swiftly and your exposure will be minimized. This is where common sense comes in. I will never delay updating a critical software to a newer version that fixes a bug because I don't like the newer version's interface. A little hint here: based on my professional experience, updating a system first, THEN checking what/if-something doesn't work is the best way to maintain a system. This also depends on the distro you are using. If you are using distro X because "ZOMGWTFBBL it uses the latest version of text editor nobody uses!!!ZOMGWTFLOLBEES" then ditch it and start using distros created before the other distro's creators were even born. In other words, if you are using a debian derivative, STOP as soon as possible (yesterday would be nice) and start using debian. Use the money you saved from unscheduled downtimes, things breaking right and left, and support financially debian. If I was a developer and was starving to death, I wouldn't sit down and code the bug fix for you. If you offered me a piece of pizza, then sure as hell I would sit down. I would even fix that other bug that is affecting you but isn't so serious.

q54e3w

Only ET IQRisk Blocklist picks up all of these IPs.

Would be great to be able to get access to this at a Snort consumer licence or similar price. I asked a few months back and was told ET got rid of it due to abuse by enterprise customers abusing the offer.

One thing that would be a reassuring addition for the dashboard widget would be a date/timestamp when the rules were last updated.

I'm very impressed with Suricata and this threads guidance, thank you.

BBcan177

@irj972:

Only ET IQRisk Blocklist picks up all of these IPs.

Would be great to be able to get access to this at a Snort consumer licence or similar price. I asked a few months back and was told ET got rid of it due to abuse by enterprise customers abusing the offer.

Would be good if they change their minds. More People need to speak up and ask them for a better package.

One thing that would be a reassuring addition for the dashboard widget would be a date/timestamp when the rules were last updated.

This is already part of my latest widget.

https://forum.pfsense.org/index.php?topic=78062.msg432181#msg432181