attack-coverage

An excel-centric approach for managing the MITRE ATT&CK® tactics and techniques.

the goal

The Excel file AttackCoverage.xlsx can be used to get a coverage measure of MITRE ATT&CK® tactics and techniques, in terms of detections rules. Working as DFIR consultants for different companies, with different SOCs and technologies in place, it was needed a simple and portable way to get a sort of awareness about which attackers’ tactics/techniques a customer is able to detect and, more important, what is missing.

AttackCoverage.xlsx

Before a brief explanation about the usage, please consider that all the 7 worksheets share specific characteristics. The header of each worksheet has colours: gray means a static fields, strings or numbers; blue means calculated values, with formulas; white means columns (cells) that expect an input from the users. Usually you will not mess with gray or blue columns, with exceptions. White columns with “Active” or “IsActive” captions expect to be blank or filled with the string “yes“: there is not a “no“, just “yes” or blank.

adding the first detection rule

From the blue team perspective, the great part of the job will be done in the detections worksheet. Here is where you’ll set your detection rules: the provided worksheet has the first four columns as an example, and you can add/remove/change them. Unless you’re modifying the excel, do not touch the “is active” and “attack1..3” columns. Let’s insert the first detection rule, which aims to detect attackers’ attempt to access the LSASS Memory, sub-technique T1003.001.

adding detection rule

The first columns, the gray ones, are up to you. If you want to make the detection rule active, simply write yes in the column. To map that specific rule to one or more (could be) Attack Techniques/Sub-Techniques, just use the attack1..3 columns.

Let’s switch on techniques worksheet. As you will see, we have two red lines: one for T1003.001 (LSASS Memory sub-technique) and one for T1003, the technique which T1003.001 belongs to.

techniques

The red colouring reflects the inconsistent state reported in column technique status. It means you have a detection rule for a specific (sub)technique but your’re missing any data source required to detect it: check the column data source available, which is zero. Techniques data sources are written in the data sources column, separated by a pipe ‘|’. To “solve” the issue you can: disable the rule since it can’t work; fix the missing data source as shown in the next picture, by accessing the source worksheet and putting “yes” in the proper field.

sources

the techniques worksheet

Going back to the techniques worksheet you’ll get two green lines and multiple yellow ones. First, the green ones: since you have the proper (or, better, a proper) data source for the detection rule, the technique status changed to detect. It means you could be able to detect that specific sub-technique T1003.001. Moreover, since you’re detecting a sub-technique, the “father” technique T1003 will reflect this detection too, in a slightly different way. The “default counting rule” follows:

By default the minimum number of expected detection rules is 1 for Techniques without any sub-technique. For Techniques with one or more sub-techniques, the minum number of expected detection rules is the number of sub-techniques. This number is automatically calculated and reported in the “minimum detection rules” column.

In the current scenario, the minimum expected detection rule for T1003.001 is 1, while for T1003 (the Technique) is 8 because “OS Credential Dumping” has eight sub-techniques. What about the yellow lines (“technique status” equals to “no detect“)? Since you’ve enabled a data source, any technique using that data source could be detected: in different words, you have the data to detect those techniques but no detections rules in place! Time to fill the gaps!

techniques

the STATUS and the COVERAGE worksheets

What you are currently detecting in terms of techniques and sub-techniques, organized by tactics, is shown into the STATUS worksheet. It’s a better view of the work done, what you’re missing entirely (no data sources available!) and what you could detect if you’ll prepare the proper detection rules.

STATUS

Wait a moment. Why in the STATUS cells related to T1003 and T1003.001 we have 0 detection rules and 1 detection rules? And both are green?“. Remember that the STATUS worksheet represents what you are detecting (techniques and sub-techniques) and what you are not. For the coverage there is the COVERAGE worksheet. As shown in the next picture, the COVERAGE will report 13% for the Technique, since you have just 1 out of 8 detection rules expected for T1003.

COVERAGE

You’ll spot that COVERAGE will address only Techniques organized in the “classic” Attack way, by Tactics. In the end, for each Tactics, you’ll get the total coverage.

I have a new fancy sub-technique not included in the Attack framework!

This is supercool, and the Excel file is already built to cover that. Place the detection rule by using the detection worksheet and assign to the “OS Credential Dumping (T1003)” technique, since it will not apply to any of the sub-techniques described by the Attack framework.

detections

Go back to techniques: now you got 2 detection rules for T1003, one from T1003.001 and one directly applied to T1003 (column “detection rules for technique“). Unfortunately this is unexpected: techniques with sub-techniques are not expected to have detection rules applied directly to them! This error is reported in the “Error checks” column: always check it!

techniques

You can’t have more detection rules than the expected ones! Coverage will be wrong. Remember the minimum expected ones: 1 for Techniques without any sub-technique; n for Techniques with n sub-techniques and 0 for the Technique itself.

How to handle that? Easy, that’s the reason of the white column “detection rules modifier“. Just add 1 to the T1003 related cell: it means we expect a detection rule that will direclty target the “main” Technique T1003. See the pictures.

techniques

No more errors: STATUS and COVERAGE will reflect this new addendum.

STATUS

COVERAGE

I want to disable some techniques/sub-techniques, I don’t need them

Again, the Excel file is built to support this, by using the “detection rules modifier” in the techniques worksheet. Suppose you want to disable “At (Linux) (T1053.001)” sub-technique since you have no Linux hosts. Simply put -1 in the cell related to T1053.001, as shown in the next pictures.

techniques

This will be reflected in the STATUS too: note that T1053.001 is used in different Tactics.

STATUS

What if you want to disable not just that sub-technique but the whole T1053 one? Simply put -1 in each sub-technique belonging to T1053, as shown: you don’t need to put a -1 to the Technique itself, unless it’s a Technique without sub-techniques.

techniques

Again, the disabled technique (and its sub-techniques) will be shown in STATUS.

STATUS

What about the COVERAGE? It will reflect this fact by putting 100% for the Technique. It could sound weird, but indeed it’s better not to remove it to maintain the awaraness.

COVERAGE

I have a custom data source not in the Attack list!

This is a bit annoying to update. Use the sources worksheet and insert a new row: this insertion will update the table. For example, insert the Custom data source as shown

sources

Then, for each of the techniques involved by this new source you have to update the data sources column in the techniques worksheet: remember that each source is separated by the pipe, “|”.

techniques

Not the best solution, indeed. A better one should be implemented. After the update, the T1098 will become yellow, as expected.

techniques

how to update

I will update the Excel file when new Attack version will be available. Still, if you’ll have a filled Excel file you need a way to update your own. As you can see in this repository, there is a folder called 20201030: this folder contains the files used to create the actual AttackCoverage.xlsx. The most important files are the .csv ones, because they are used to fill the “static” (gray columns) cells for sources (file: data_sources.csv), tactics (file: tactis.csv) and techniques (file: techniques.csv). I will then recreate those file for the new version(s), and you can simply diff those CSV files to properly update/insert/remove the related lines in your Excel file. It could be “complicated” in case of new tactics (as version 8 did), because wrongly updating STATUS and COVERAGE worksheets would introduce errors: so pay attention or “shout” an issue here.

how is built

As explained in the “how to update” section, the starting files to build AttackCoverage.xlsx are the CSV ones. Those files are built by using the Python3 scripts you’ll find in the script folder: you can use by yourselves to build your own coverage approach. There is one major requirement, which is the (awesome) attackcti library provided by Roberto Rodriguez (@Cyb3rWard0g) and Jose Luis Rodriguez (@Cyb3rPandaH). Then the Excel file is using tables, formulas and conditional formatting: easy as it is, no macro(s) in place ?

Note that in the version worksheet is reported the Attack Framework version used: in the current scenario is version 8, October 2020. Cell “Based on template version” is used to track the different customers’ excel files used to create their own, while “Current Excel file version” reflects any modification made to a specific instance (eg: when adding a new detection rule, etc.).

credits

Kudos and thanks to Roberto Rodriguez (@Cyb3rWard0g) for his attackcti framework and, more important, for the inspiration I got from his blog post “How Hot Is Your Hunt Team? ” at https://cyberwardog.blogspot.com/2017/07/how-hot-is-your-hunt-team.html

GitHub

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