The Intrusion Prevention System (IPS) system of Ixolate is based on Suricata and utilizes Netmap to enhance performance and minimize CPU utilization. This deep packet inspection system is very powerful and can be used to detect and mitigate security threats at wire speed.
IDS and IPS
It is important to define the terms used in this document. An Intrustion Detection System (IDS) watches network traffic for suspicious patterns and can alert operators when a pattern matches a database of known behaviors. An Intrusion Prevention System (IPS) goes a step further by inspecting each packet as it traverses a network interface to determine if the packet is suspicious in some way. If it matches a known pattern the system can drop the packet in an attempt to mitigate a threat.
The Suricata software can operate as both an IDS and IPS system.
Choosing an interface
You can configure the system on different interfaces. One of the most commonly asked questions is which interface to choose. Considering the continued use IPv4, usually combined with Nat, it is quite important to use the correct interface. If you are capturing traffic on a WAN interface you will see only traffic after address translation. This means all the traffic is originating from your firewall and not from the actual machine behind it that is likely triggering the alert.
Rules for an IDS/IPS system usually need to have a clear understanding about the internal network; this information is lost when capturing packets behind NAT.
Without trying to explain all the details of an IDS rule (the people at Suricata are way better in doing that), a small example of one of the ET-Open rules usually helps understanding the importance of your home network.
alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"ET TROJAN Observed Glupteba CnC Domain in TLS SNI"; flow:established,to_server; tls_sni; content:"myinfoart.xyz"; depth:13; isdataat:!1,relative; metadata: former_category MALWARE; reference:md5,4cc43c345aa4d6e8fd2d0b6747c3d996; classtype:trojan-activity; sid:2029751; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, deployment Perimeter, signature_severity Major, created_at 2020_03_30, updated_at 2020_03_30;)The \$HOME_NET can be configured, but usually it is a static net defined in RFC 1918. Using advanced mode you can choose an external address, but bear in mind you will not know which machine was really involved in the attack and it should really be a static address or network.
\$EXTERNAL_NET is defined as being not the home net, which explains why you should not select all traffic as home since likely none of the rules will match.
Since the firewall is dropping inbound packets by default it usually does not improve security to use the WAN interface when in IPS mode because it would drop the packet that would have also been dropped by the firewall.
General setup
The settings page contains the standard options to get your IDS/IPS system up and running.
| Enabled | Enable Suricata |
| Capture mode | Choose between “PCAP live move (IDS)” for alerts only, “Netmap (IPS)” for alerts and discards via netmap driver, or “Divert (IPS)” to redirect packets via firewall rules. The action for a rule needs to be “drop” in order to discard the packet, this can be configured per rule or ruleset (using an input filter) |
| Listeners | When “Divert (IPS)” mode is used, specify the number of listeners to initiate, usually this equals the number of CPUs in your system. |
| Promiscuous mode | Listen to traffic in promiscuous mode. (all packets instead of only the ones addressed to this network interface) |
| Enable syslog alerts | Send alerts to syslog, using fast log format |
| Enable eve syslog output | Send alerts in EVE format to syslog, using log level info. This will not change the alert logging used by the product itself. Drop logs will only be send to the internal logger, due to restrictions in suricata. |
| Pattern matcher | Controls the pattern matcher algorithm. Aho–Corasick is the default. On supported platforms, Hyperscan is the best option. On commodity hardware if Hyperscan is not available the suggested setting is “Aho–Corasick Ken Steele variant” as it performs better than “Aho–Corasick”. |
| Interfaces | Interfaces to protect. When in IPS mode, this needs to be real interfaces supporting netmap. (when using VLANs, enable IPS on the parent) |
| Rotate log | Log rotating frequency, also used for the internal event logging (see Alert tab) |
| Save logs | Number of logs to keep |
Advanced options
Some less frequently used options are hidden under the “advanced” toggle.
| Home networks | Define custom home networks, when different than an RFC1918 network. In some cases, people tend to enable IDPS on a wan interface behind NAT (Network Address Translation), in which case Suricata would only see translated addresses instead of internal ones. Using this option, you can define which addresses Suricata should consider local. |
| default packet size | With this option, you can set the size of the packets on your network. It is possible that bigger packets have to be processed sometimes. The engine can still process these bigger packets, but processing it will lower the performance. |
Download rulesets
When enabling IDS/IPS for the first time the system is active without any rules to detect or block malicious traffic. The download tab contains all rulesets available on the system (which can be expanded using plugins).
In this section you will find a list of rulesets provided by different parties and when (if installed) they where last downloaded on the system. In previous versions (prior to 21.1) you could select a “filter” here to alter the default behavior of installed rules from alert to block. As of 21.1 this functionality will be covered by Policies, a separate function within the IDS/IPS module, which offers more fine grained control over the rulesets.
Policies
The policy menu item contains a grid where you can define policies to apply to installed rules. Here you can add, update or remove policies as well as disabling them. Policies help control which rules you want to use in which manner and are the preferred method to change behaviour. Although you can still update separate rules in the rules tab, adding a lot of custom overwrites there is more sensitive to change and has the risk of slowing down the user-interface.
A policy entry contains 3 different sections. First some general information, such as the description and if the rule is enabled as well as a priority. Overlapping policies are taken care of in sequence, the first match with the lowest priority number is the one to use.
Secondly there are the matching criteria, these contain the rulesets a policy applies on as well as the action configured on a rule (disabled by default, alert or drop), finally there is the rules section containing the metadata collected from the installed rules, these contain options as affected product (Android, Adobe flash, …) and deployment (datacenter, perimeter).
The last option to select is the new action to use, either disable selected rules, only alert on them or drop traffic when matched.
Installed rules
The rules tab offers an easy to use grid to find the installed rules and their purpose, using the selector on top one can filter rules using the same metadata properties available in the policies view.
User defined rules
Most of the rules being used on your IDPS system will be supplied by third party vendors like Proofpoint, but in some cases it can be convenient to build some (limited) rules yourself. The “User defined” tab offers this functionality.
Fingerprinting
Ixolate includes a very polished solution to block protected sites based on their SSL fingerprint. You can manually add rules in the “User defined” tab.
Bypassing the engine
The Bypass toggle offers the ability to skip traffic inspection, our How-tos section contains a good example to exclude local traffic passing your network and increase routing performance.
Alerts
In the “Alerts” tab you can view the alerts triggered by the IDS/IPS system. Use the info button here to collect details about the detected event or threat.
Advanced configuration
Since this file is parsed by our template system, you are able to use template tags using the Jinja2 language.
Available rulesets
Emerging Threats
Emerging Threats (ET) has a variety of IDS/IPS rulesets. There is a free, BSD-licensed version and a paid version available.
ET Open
The ETOpen Ruleset is not a full coverage ruleset and may not be sufficient for many regulated environments and thus should not be used as a standalone ruleset.
Ixolate has integrated support for ETOpen rules.
ETPro Telemetry
Proofpoint offers a free alternative for the well known Etpro telemetry ruleset.
ETPro (commercial)
When in possession of a Proofpoint ET Pro oink code, you can install the os-intrusion-detection-content-et-pro plugin via System › Firmware › Plugins.
As soon as the plugin is installed, you will find an option etpro.oinkcode under settings in Services › Intrusion Detection › Administration / Download where you can enter this code.
Abuse.ch
Abuse.ch offers several blacklists for protecting against fraudulent networks.
SSL Blacklist
SSL Blacklist (SSLBL) is a project maintained by abuse.ch. The goal is to provide a list of “bad” SSL certificates identified by abuse.ch to be associated with malware or botnet activities. SSLBL relies on SHA1 fingerprints of malicious SSL certificates and offers various blacklists.
See for details: https://sslbl.abuse.ch/
Feodo Tracker
Feodo (also known as Cridex or Bugat) is a Trojan used to commit ebanking fraud and steal sensitive information from the victim’s computer, such as credit card details or credentials. At the moment, Feodo Tracker is tracking four versions of Feodo, and they are labeled by Feodo Tracker as version A, version B, version C and version D:
- Version A Hosted on compromised webservers running an nginx proxy on port 8080 TCP forwarding all botnet traffic to a tier 2 proxy node. Botnet traffic usually directly hits these hosts on port 8080 TCP without using a domain name.
- Version B Hosted on servers rented and operated by cybercriminals for the exclusive purpose of hosting a Feodo botnet controller. Usually taking advantage of a domain name within ccTLD .ru. Botnet traffic usually hits these domain names using port 80 TCP.
- Version C Successor of Feodo, completely different code. Hosted on the same botnet infrastructure as Version A (compromised webservers, nginx on port 8080 TCP or port 7779 TCP, no domain names) but using a different URL structure. This Version is also known as Geodo and Emotet.
- Version D Successor of Cridex. This version is also known as Dridex
See for details: https://feodotracker.abuse.ch/
URLHaus List
Ixolate version 18.1.7 introduced the URLHaus List from abuse.ch which collects compromised sites distributing malware.
See for details: https://urlhaus.abuse.ch/
App detection rules
Ixolate 18.1.11 introduced the app detection ruleset. Since about 80 percent of traffic are web applications these rules are focused on blocking web services and the URLs behind them.