Adding Local Rules

NIDS

You can add NIDS rules in /opt/so/saltstack/local/salt/idstools/local.rules on your manager. Within 15 minutes, Salt should then copy those rules into /opt/so/rules/nids/local.rules. The next run of idstools should then merge /opt/so/rules/nids/local.rules into /opt/so/rules/nids/all.rules which is what Suricata reads from.

If you don’t want to wait for these automatic processes, you can run them manually from the manager (replacing $SENSORNAME_$ROLE as necessary):

sudo salt-call state.highstate
sudo so-rule-update
sudo salt $SENSORNAME_$ROLE state.apply suricata

For example:

  • Let’s add a simple rule to /opt/so/saltstack/local/salt/idstools/local.rules that’s really just a copy of the traditional id check returned root rule:

    alert ip any any -> any any (msg:"GPL ATTACK_RESPONSE id check returned root 2"; content:"uid=0|28|root|29|"; classtype:bad-unknown; sid:7000000; rev:1;)
    
  • From the manager, tell Salt to update:

    sudo salt-call state.highstate
    
  • Update rules:

    sudo so-rule-update
    
  • Restart Suricata (replacing $SENSORNAME_$ROLE as necessary):

    sudo salt $SENSORNAME_$ROLE state.apply suricata
    
  • If you built the rule correctly, then Suricata should be back up and running.

  • You can then run curl http://testmynids.org/uid/index.html on the node to generate traffic which should cause this rule to alert (and the original rule that it was copied from, if it is enabled).

YARA

Default YARA rules are provided from Florian Roth’s signature-base Github repo at https://github.com/Neo23x0/signature-base.

Local Rules:

To add local YARA rules, create a directory in /opt/so/saltstack/local/salt/strelka/rules, for example localrules. Inside of /opt/so/saltstack/local/salt/strelka/rules/localrules, add your YARA rules.

After adding your rules, update the configuration by running so-strelka-restart.

Remotely Managed Rules:

To have so-yara-update pull YARA rules from a Github repo, copy /opt/so/saltstack/local/salt/strelka/rules/, and modify repos.txt to include the repo URL (one per line).

Next, run so-yara-update to pull down the rules. Finally, run so-strelka-restart to allow Strelka to pull in the new rules.