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mindmup-as-attack-trees

Python scripts for using mindmup .mup JSON as a medium for developing attack trees.

In General:

  1. Create an attack tree with mindmup -- legacy version 1 also supported: you can use https://github.com/BenGardiner/legacy-mindmup for offline creation of attack trees.

  2. Save the .mup locally

  3. Use these scripts to do the following steps (can be done indivdiually or in a batch depending on your workflow).

Step Description Script in scripts/
0 normalize the .mup JSON -- useful before comitting to SCM to reduce diff noise normalize-json
1 check the .mup for problems (e.g. duplicate nodes, missing references, missing EVITA:: tags) and strips hidden sections checks.py
2 number the nodes in the .mup, resolving references to nodes in the tree (and undo this) add-numbered-ids.py (remove-numbered-ids.py)
3 resolve any 'in-text' references to nodes resolve-stdin.py
4 propagate and calculate the required attack potentials and risks based on the model in the .mup file (and undo this) add-evita.py (remove-evita.py)
5 generate a report from the .mup -- including renderings of the subtrees as images in-line generate-descriptions-md-template
6 generate a risk analysis section for the report from the .mup generate-evita-chart.py
  1. Publish the report as markdown+images or convert to format of your choice (with e.g. pandoc)

In Detail:

  1. Collaborate on (this was alot better before mindmup 2.0), or otherwise create an attack tree in mindmup.

    • This .mup file will serve as the container for the attack trees from objectives through attack vectors to mitigations -- including also descriptive text and weightings for severities and required attack potentials.

    • There are some special strings and properties that will be recognized by the processing later:

      • AND for an and-ing operation on subtrees
      • (*) for references to other nodes defined elsewhere in the tree
      • ... for nodes unspecified
      • ```.hidden`` for hiding nodes in the .mup that will not be rendered in the report
      • Mitigation: <anything> for capturing mitigations to attacks both on attack vectors and mid-tree

    • There are some special 'tags' that should be inserted in the descriptions of the nodes

      • OBJECTIVE:: for classifying a node as an attacker objective, where both attacker motivation and impact on stakeholders is clear also
      • RISK_HERE:: for specifying a point in the tree where risk should be calculated, if in doubt place these on OBJECTIVE:: nodes
      • OUT_OF_SCOPE:: for marking a node out-of-scope for this analysis. This node will still need estimated Required Attack Potentials but does not need to have its subtree expanded in detail or any mitigations captured
      • EVITA:: |S|S|S|S|R|R|R|R|R for ascribing estimates of severity (S fields) and estimates of Required Attack Potential (RAP) (R fields). These are required on OBJECTIVE:: nodes and also for attack vectors. Severities are ascribed to OBJECTIVE:: nodes, whereas RAPs are ascribed to attack vectors.
      • SUBTREE:: for breaking-up large attack trees into smaller 'snapshots'/'subtrees' when rendered in the report

    • Finally, any free-form text can be put into the node descriptions as markdown (saved as HTML-wrapped markdown). You should include descriptions of any attack vector nodes as well as some justification text of the RAPs ascribed. Similarly for objective nodes, descriptions should be written that explain attacker motivations and justify the severities ascribed.

  2. download the mindmup .mup file

    e.g. see examples/steps/0_Compromise (P)RNG Somehow.mup

  3. normalize the JSON with normalize-json. This is useful if you are going to commit the mindmup to a SCM as it will minimize line-diffs in the future.

    e.g. normalize-json < examples/steps/0_Compromise\ \(P\)RNG\ Somehow.mup > examples/steps/1_Compromise\ \(P\)RNG\ Somehow.mup

  4. add numbering to the tree with add-numbered-ids.py

    • you can later re-number the nodes by running remove-numbered-ids.py then add-numbered-ids.py again.

    e.g. add-numbered-ids.py < examples/steps/1_Compromise\ \(P\)RNG\ Somehow.mup examples/steps/2_Compromise\ \(P\)RNG\ Somehow.mup

  5. add calculations of all Required Attack Potentials troughout the tree and estimates of risk as the RISK_HERE:: with add-evita.py.

    • you can later re-calculate these by running remove-evita.py then add-evita.py again.

    e.g. add-evita.py < examples/steps/0_Compromise\ \(P\)RNG\ Somehow.mup > examples/steps/1_Compromise\ \(P\)RNG\ Somehow.mup

  6. generate a template report for the now-numbered tree using generate-descriptions-md-template. This will create a markdown template and some subtrees snapshot .mup files. The template includes inline .png images that need to be rendered from those .mup files.

    e.g. mkdir examples/steps/3_Report && cd examples/steps/3_Report && ../../../generate-descriptions-md-template < ../2_Compromise\ \(P\)RNG\ Somehow.mup > Report.md

  7. for each of the subtree snapshot .mup files: render a .png file using rendermup

  8. add a risk analysis section to the report with generate-evita-chart.py

  9. iteratively edit the template, including descriptions, impacts, severities etc. to achieve a draft report

  10. publish the markdown+images.

Calculation of Combined Attack Probability and Risk

By adding tags to the mindmup text you can structure the attack tree to include attacker objectives with associated severities and attack vectors with associated required attack potentials. Then the scripts will calculate and propagate the required attack potentials up the tree and marry them with the severities to estimate risks. This calculation is performed according to the method detailed in Security requirements for automotive on-board networks based on dark-side scenarios

The 5 scores of Required Attack Parameters are based on the vulnerability assessment section of *Common Methodology for Information Technology Security Evaluation (CEM v3.1)

Other Scripts

Script Name Description
forward-references.py re-orders the nodes so that all concrete subtrees occur before references to those subtrees