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Difference between revisions of "Abuse Case Cheat Sheet"
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− | + | [[User:Rick.mitchell|Rick Mitchell]] | |
= Other Cheatsheets = | = Other Cheatsheets = |
Revision as of 08:12, 29 September 2018
Last revision (mm/dd/yy): 09/29/2018 IntroductionOften when the security level of an application is mentioned in requirements, the following expressions are meet:
These security requirements are too generic and useless for a development team... To build a secure application, from an pragmatic point of view, it is important to identify the attacks which the application must defend against according to its business and technical context. ObjectiveThe objective of this cheat sheet is to provide a explanation about what an Abuse Case is, why abuse cases are important when considering the security of an application and, finally, to provide a proposal for a pragmatic approach to built a list of abuse cases and track them for every feature planned to be implemented as part of an application whatever project mode used (waterfall or agile). Important note about this Cheat Sheet: The main objective is to provide a pragmatic approach in order to allow a company or a project team to start building and handling the list of abuse cases and then customize the elements proposed to its context/culture in order to, finally, build its own method. This cheat sheet can be seen like a getting started tutorial. Context & approachWhy clearly identify the attacks?Clearly identifying the attacks against which the application must defend is essential in order to enable the following steps in a project or sprint:
Notion of Abuse CaseIn order to help build the list of attacks, the notion of Abuse Case exists. An Abuse Case can be defined as: A way to use a feature that was not expected by the implementer, allowing an attacker to influence the feature or outcome of use of the feature based on the attacker action (or input). Synopsys define an 'Abuse Case like this: Misuse and abuse cases describe how users misuse or exploit the weaknesses of controls in software features to attack an application. This can lead to tangible business impact when a direct attack against business functionalities, which may bring in revenue or provide positive user experience, are attacked. Abuse cases can also be an effective way to drive security requirements that lead to proper protection of these critical business use cases. Synopsys source: https://www.synopsys.com/blogs/software-security/abuse-cases-can-drive-security-requirements/ Another definition of Abuse Case by Cigital: https://cigital.com/papers/download/misuse-bp.pdf How to define the list of Abuse Cases?There are many different ways to define the list of abuse cases for a feature (that can be mapped to a user story in agile mode).
Further considering the threats to the organization, conduct a more formal analysis to determine potential misuse or abuse of functionality. Typically, this process begins with identification of normal usage scenarios, e.g. use-case diagrams if available. If a formal abuse-case technique isn’t used, generate a set of abuse-cases for each scenario by starting with a statement of normal usage and brainstorming ways in which the statement might be negated, in whole or in part. The simplest way to get started is to insert the word “no” or “not” into the usage statement in as many ways as possible, typically around nouns and verbs. Each usage scenario should generate several possible abuse-case statements. Further elaborate the abuse-case statements to include any application-specific concerns based on the business function of the software. The ultimate goal is for the completed set of abuse statements to form a model for usage patterns that should be disallowed by the software. If desired, these abuse cases can be combined with existing threat models. After initial creation, abuse-case models should be updated for active projects during the design phase. For existing projects, new requirements should be analyzed for potential abuse, and existing projects should opportunistically build abuse-cases for established functionality where practical. Open SAMM source: Threat Assessment Level 2 Actvity A Another way to achieve the building of the list can be the following (more ground and collaborative oriented): Make a workshop that includes people with the following profiles:
It is important to take in account Technical and Business kind of abuse cases and mark them accordingly. Example:
When to define the list of Abuse Cases?On agile project, the definition workshop must be made after the meeting in which User Stories are associated to a Sprint. On waterfall project, the definition workshop must be made when business feature to implements are identified and known by the business.
An example of unique ID can be ABUSE_CASE_001.
ProposalThe proposal will use the workshop explained in previous section and will focus on the output of the workshop. Step 1: Preparation of the workshopFirst, even if it seems obvious, the key business people must be sure to know, understand and be able to explain the business features that will be processed during the workshop. Secondly, create a new Microsoft Excel file (you can also use Google Sheets or any other similar software) with the following sheets (or tabs):
FEATURES sheet:
Step 2: During the workshopUse the spreadsheet to review all the features. For each feature, follow this flow:
With the time and across projects, you will obtain your own dictionary of attacks and countermeasures that are applicable to the kind of application in your business domain. This dictionary will speed up the future workshops in a significant way. To promote the creation of this dictionary, you can, at the end of the project/sprint, gather the list of attacks and countermeasures identified in a central location (wiki, database, file...) that will be used during the next workshop in combination with the input of the offensive guys. Step 3: After the workshopThe spreadsheet contains (at this stage) the list of all abuse cases that must be handled and, potentially (depending on the capacity) corresponding countermeasures. Now, there 2 remaining task:
Step 4: During implementation - Abuse cases handling trackingIn order to track the handling of all the abuse cases, the following approach can be used: If one or several abuse cases are handled at:
Using this way, it becomes possible (via some minor scripting) to identify where the the abuse cases are addressed. Step 5: During implementation - Abuse cases handling validationAs abuse cases are defined, it is possible to put in place automated or manual validations to ensure that:
Add automated tests also allow teams to track that countermeasures against the abuse cases are still effective/in place during maintenance or bug fixing phase of a project (prevent accidental removal/disabling). It is also useful when Continuous Delivery approach is used (https://continuousdelivery.com/) to ensure that all abuse cases protections are in place before opening access to the application. Sources of the schemasAll schemas were created using https://www.draw.io/ site and exported (as PNG image) for integration into this article. All XML descriptor files for each schema are available below (using XML description, modification of the schema is possible using DRAW.IO site): Authors and Primary EditorsDominique Righetto - [email protected] Other Cheatsheets |