Triage

Threat Hunting at speed and scale

Almost every case starts with one or more leads. If there are too many leads, the investigator might need to validate all their leads one by one, which is very time-consuming. Or, if there are too few leads, investigators don't have enough information to continue their case. Both situations are not good for the investigation and can impact the speed of resolution.

Triage is the process of hunting for and prioritizing the evidence that they’ll be analyzing. However, prioritizing this evidence is not a straightforward or easy job. An Investigator needs lots of data, leads, or experience to do it well. So, they generally use known attack indicators, called the IOC indicator of the compromise. An indicator of compromise (IoC) in computer forensics is an artifact observed on a network or in an operating system that, with high confidence, indicates a computer intrusion.

An investigator or analyst will generally scan all system data or part of it to discover these IOCs. When they see a match, it typically means that those systems are related to a specific attack type and need to be investigated first. Investigators use YARA, osquery, and Sigma rules for these scans. Investigators can define and scan IOCs by using AIR's built-in YARA, osquery, and Sigma template rules or editors.

Binalyze AIR DFIR Suite provides three different tools to the investigators for triage, which, as stated, are YARA, osquery, and Sigma. These tools generally scan assets to find specific data using IOC (Indicator of Compromise).

YARA (Yet Another Recursive Acronym) is a tool aimed at (but not limited to) helping malware researchers identify and classify malware samples. With YARA you can create descriptions of malware families (or whatever you want to describe) based on textual or binary patterns. Each description, a.k.a. rule, consists of a set of strings and a boolean expression that determine its logic.

Sigma is a generic and open signature format that allows you to describe relevant log events in a straightforward manner. The rule format is very flexible, easy to write, and applicable to any type of log file. The main purpose of this project is to provide a structured form in which researchers or analysts can describe their once-developed detection methods and make them shareable with others. Sigma is for log files what Snort is for network traffic and YARA is for files.

osquery, an open-source tool, employs SQL-like queries to extract intricate system data. It offers cross-platform compatibility, making it ideal for real-time system monitoring, security analysis, and compliance assessments. Security professionals often use it to detect vulnerabilities, monitor system changes, and ensure adherence to security standards.

Binalyze AIR features a library for YARA, osquery, and Sigma rules, allowing investigators to develop, validate, and manage their rules directly within the platform using the built-in editors. These rules can be saved to Libraries > Triage Rules in AIR.

Investigators can easily threat hunting and scan their assets by selecting the necessary rules from the library. The Triage process flow, depicted below, illustrates how organizational policies allow administrators to control AIR’s functionality and define role-based permissions for specific activities.

Creating a case in AIR also enables users to centralize all collections, triage results, and activities related to a specific incident or investigation. This integration empowers the Investigation Hub to dynamically present everything from raw evidence to automated DRONE findings in a unified view.

Triage creation and execution in AIR

NB: Character limitation for single triage rule

• To prevent the browser becoming unresponsive we have limited the maximum to 350K characters in a single Triage Rule.

Tagging Triage Rules

Triage rules in the AIR console can be allocated Tags, which help to organize the rules and filter them when required. This feature for triage rules aids in managing them more efficiently and allows for streamlined searches and better organization within the console.

When creating or using a Triage Rule, the UI allows the user to filter existing rules by their associated Tags.

The Triage Rule Library includes Preset Filters in the secondary menu, allowing users to organize rules hierarchically, also known as 'Nested Tagging'. By incorporating a colon in their tags, users can structure and categorize rules more efficiently. For example, the tag "APT26:Tim:hashset" helps organize related rules under a structured hierarchy, enhancing navigation and accessibility in the library.

Organize triage rules hierarchically - 'Nested Tagging'

Scan Local Drives Only for Triage Tasks

With the Scan Local Drives Only feature, users can improve Yara triage efficiency by focusing threat hunting and triage scans solely on local drives, excluding remote external or network drives that often introduce unnecessary data into the investigation. The attached mounted USB drives should be included as ‘local drives’.

Key Details:

• Available for all AIR-supported operating systems.

• Disabled by default but can be enabled via the organizational policies page: Settings>Policies>Scan Local Drives Only.

Settings>Policies>Scan Local Drives Only

• It can also be configured when creating individual triage tasks using the custom options:

This feature ensures that only relevant data from local drives is collected, reducing noise and improving the speed and accuracy of investigations.