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Monday, February 06, 2023

Why Lists?

So much of what we see in cybersecurity, in SOC, DFIR, red teaming/ethical hacking/pen testing, seems to be predicated on lists. Lists of tools, lists of books, lists of sites with courses, lists of free courses, etc. CD-based distros are the same way, regardless of whether they're meant for red- or blue-team efforts; the driving factor behind them is often the list of tools embedded within the distribution. For example, the Kali Linux site says that it has "All the tools you need". If you go to the SANS SIFT Workstation site, you'll see the description that includes, "...a collection of free and open-source incident response and forensic tools." Here's a Github site that lists "blue team tools"...but that's it, just a list.

Okay, so what's up with lists, you ask? What's the "so, what?" 

Lists are great...they often show us new tools that we'd hadn't seen or heard about, possibly tools that might be more effective or efficient for us and our workflows. Maybe a data source has been updated and there's a tool that addresses that new format, or maybe you're run across a case that includes the use of a different web browser, and there's a tool that parses the history for you. So, having lists is good, and familiar...because that's the way we've always done it, right? A lot of folks developing these lists came into the industry themselves at one point, looked around, and saw others posting lists. As such, the general consensus seems to be, "share lists"...either share a list you found, or share a list you've added to.

Lists, particularly checklists, can be useful. They can ensure that we don't forget something that's part of a necessary process, and if we intentionally and purposely manage and maintain that checklist, it can be our documentation; rather than writing out each step in our checklist as part of our case notes/documentation, we can just say, "...followed/completed the checklist version xx.xx, as of Y date...", noting any discrepancies or places we diverged. The value of a checklist depends upon how it's used...if it's downloaded and used because it's "cool", and it's not managed and never updated, then it's pretty useless.

Are lists enough?

I recently ran across a specific kind of list...the "cheat sheet". This specific cheat sheet was a list of Windows Event Log record event IDs. It was different from some other similar cheat sheets I'd seen because it was broken down by Windows Event Log file, with the "event IDs of interest" listed beneath each heading. However, it was still just a list, with the event IDs listed along with a brief description of what they meant.

However, even though this cheat sheet was "different", it was still just a list and it still wasn't sufficient for analysis today. 

Why is that?

Because a simple list doesn't give you the how, nor does it give you the why. Great, so I found a record with that event ID, and someone's list said it was "important", but that list doesn't tell me how this event ID is important to nor used in my investigation, nor how I can leverage that event ID to answer my investigative questions. The cheat sheet didn't tell me anything about how that specific event ID 

We have our lists, we have our cheat sheets, and now it's time to move beyond these and start developing the how and why; how to use the entry in an investigation, and why it's important. We need to focus less on simple lists and more on developing investigative goals and artifact constellations, so that we can understand what that entry means within the overall context of our investigation, and what it means when the entry is absent. 

We need to share more about how the various items on our lists are leveraged to reach or further our investigative goals. Instead of a list of tools to use, talk about how you've used one of those tools as part of your investigative process, to achieve your investigative goals.

Having lists or cheat sheets like those we've been seeing perpetuates the belief that it's sufficient to examine data sources in isolation from each other, and that's one of the biggest failings of these lists. As a community, and as an industry, we need to move beyond these ideas of isolation and sufficiency; while they seem to bring about an immediate answer or immediate findings, the simple fact is that neither serves us well when it comes to finding accurate and complete answers.

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