Event Masker – 2021.08 Release

We are proud to announce a new release for Event Masker, with many productivity tweaks and significant enhancements.

ES Integration

It was cumbersome to move from the tab where you had the notable event you wanted to mask, to the tab with Event Masker opened on the correct rule. That is why you may now create a mask rule directly from Splunk Enterprise Security Incident Review panel.

By selecting the Actions drop down menu and clicking on Whitelist Notable in Event Masker, you are directed to the rule creation page. The notable events fields are prefilled, as well as the scope and name of the rule, so it is easy for you to pick what you need. Tick the boxes, tweak the lines as you see fit, and that’s it! Don’t waste anymore time copy/pasting the values!

ES Workflow action redirect to Event Masker form

Validity Period Logic

Event whitelisting based on timespan needed to be more flexible. Previously, we used the time of search to decide when to mask events. From now on, we use the generated time of the given events.

Also, we have seen that the _time field is not necessarily available at the moment you invoke the mask streaming command. Thus, we added the timefield argument to specify against which field you want time exclusions to be applied. For programmatic reasons, its format is %Y-%m-%d %H:%M:%S.%Q.

This enables, for instance, to mask a maintenance window where you see the same events again and again.

Below is an example of logs that are masked only between 10:10 AM and 10:20 AM:

Validity period

Revisited Interface

To ease your life, we moved all the parameters related to a rule on a single page. The rule properties are now above their conditions, to keep a simple and consistent view of what you are doing.

New consolidated edit form

Customizable Rule Types

Want to classify you rules your way? The list of rule types is now based on a lookup table you may edit however you’d like. You may use the well known Splunk application Lookup Editor to update event_masker_rules_type_lookup.csv.

Detailed Comments

Imagine a rule with many hash values. With the new comment column available on every condition, you can explain what it actually means. This new field grants you unprecedented capability to document the rule at the best place of all!

Dashboard and Logs

We extended the logs generated by the mask command and added logs for rule changes (currently, this feature requires write permission on _internals).

This enables new filters on existing dashboards. For instance, the mask command activity can be filtered by scope, rule title or log level.

From the rule list panel, you may jump to the logs to review all changes that occurred on this rule. We see a couple of use cases:

  • troubleshooting regression implied by a recent change
  • peer review of new whitelists

Hence, two new dashboards are available: Event Masker Logs for mask command, and Event Masker Audit Logs for rule logs. Isn’t it simple?

Event Masker logs
Event Masker Audit logs

A new panel on Event Masker Overview shows all the rules and conditions for a given scope:

Rule conditions by scope panel

Default Permission

We updated default permission to add ess_user, ess_analyst and ess_admin roles to read the app content, and added ess_admin write capabilities.

Fetch the Update

You may find the app on:

Feedback Welcomed!

We’d love hearing from you: what you achieved, what you think of it, the features you miss, and the unlikely bugs you found 😉 You may reach us with GitHub issues or at the e-mail address provided in the readme.

Last but not least, a thunder applause for SCRT’s engineers whose commitment to excellence made this update possible!

Splunk & advanced filtering with Event Masker

What is Splunk ?

Splunk is a Data-to-Everything Platform designed to ingest and analyze all kind of data. They can be visualized and correlated through Splunk searches, alerts, dashboards, and reports. Splunk is the #1 of 2020 Gartner Magic Quadrants in SIEMs for its performant analysis and visionary in Application Performance Management category.

Splunk and SCRT Analytics Team

SCRT provides its Splunk-based SIEM solution focused in first place on suspicious behavior detection through a custom library of use cases based on its on-field experience and know-how in Cyber Security.

SCRT chose Splunk Enterprise and Splunk Enterprise Security providing an integration with customer infrastructure and providing all the Splunk power to ingest, correlate, analyse and display valuable information for anomaly detection.

Nevertheless, Splunk has a lack of a viable solution for a proper whitelisting strategy that would enable users to delete part of their search results. For this purpose, SCRT has developed a custom Splunk app called “Event Masker” that provides filtering functionalities with a simple and powerful whitelist rules editor.

Event Masker

Event Masker provides filtering functionalities in Splunk, thereby permitting you to whitelist the events of your choice. Even though you can use Event Masker on any dashboard or query in the Splunk search bar, it was primarily built to reduce the number of false positives in Splunk Enterprise Security by better controlling its notable events.

Event Masker provides:

  • Rules management through an advanced interface that permits to create, import, export and edit rules properties. Each Rule contains a set of conditions, applied when Event Masker is called in a Splunk search command or correlation search.
Rules list interface
Rule’s properties
Rule’s conditions
  • The custom search command “mask” which permits to call Event Masker from the command line.

  • Some dashboards to audit the masked events and check the underlying rules.An audit log that permits to further track events that were masked over time
Event Masker Overview dashboard
Masked events over time
Rule logs

Release

Event Masker was released under CC BY-NC 4.0 and published on SplunkBase : https://splunkbase.splunk.com/app/5545/

We are pleased to provide this app freely to the Splunker’s community with a public GitHub repository https://github.com/scrt/event_masker/. Feel free to co-develop with us on this app to improve the Splunk experience and the efficiency of threats detections.

Many thanks to the whole SCRT Analytics team for its expertise and performance that permitted to achieve this great project.