CMSC 426-626: Common Criteria for Computer/IT Systems Prof. Krishna Sivalingam Oct 23, 2006

Originally released in 1998 Common Criteria Commoncriteria.org Commoncriteriaportal.org Lists CC v3.1 (and older versions) Originally released in 1998 An International Standards Organisation (ISO) standard for security evaluation of software products IT product vendors use the CC as a benchmark for product security

NIAP National Information Assurance Partnership (NIAP) is a joint venture between NIST (nist.gov) and NSA (nsa.gov) Goal: “increase the level of consumer trust in information systems and networks” from http://www.nsa.gov/ia/industry/niap.cfm One service: Common Criteria Evaluation and Validation Scheme (CCEVS) that “focuses on meeting the security testing, evaluation, and assessment needs of both IT products and consumers.”

Security concepts and relationships From CC Part 1 (of v3.1)

Evaluation concepts & relationships From CC Part 1 (of v3.1)

The PP describes the product’s protection needs CC Process A user creates Packages or “Protection Profile” for a desired security product The PP describes the product’s protection needs Written by the user (e.g. government, banking industry, vendor’s marketing group, product inventor) Describes security aspects needed in an IT product

CC Protection profile (in Combined Federal Criteria) Rationale Protection policy and regulations Information protection philosophy Expected threats Environmental assumptions Intended Use Functionality Security Features Security Services Available security mechanisms Assurance Profile-specific assurances Profile-independent assurances Dependencies Internal External

CC Protection Profile Introduction Product/System Family Description: Generic description of family of products. Product/System Family Security Environment – intended use, environment of use, threats to assets, organizational security policies, etc. Security Objectives IT Security Requirements – Functional and Assurance Rationale

What happens with PP? A vendor develops an IT product based on the requirements set in the PP Vendor then prepares a “security target” document that describes the security and assurance aspects of the product. Can relate Security Target to Specs. In the Protection Profile Security Target can also be written independent of a PP and sold along with the IT product

CC Package A package is a named set of security requirements. A package is either a functional package, containing only SFRs (Security Functional Requirements) or an assurance package, containing only SARs (Security Assurace Requirements) But, not both. Examples of Assurance packages are the EALs (Evaluation Assurance Level), than run from EAL1 (lowest) through EAL7 (highest) EAL1 through EAL4 are most common

Security Target, contd. From CC, part I: “The Security Target begins with describing the assets and the threats to those assets. The Security Target then describes the countermeasures (in the form of Security Objectives) and demonstrates that these countermeasures are sufficient to counter these threats: if the countermeasures do what they claim to do, the threats are countered.”

Security Target (per Comb Fed Crit.) Rationale Implementation fundamentals Information protection philosophy Countered Threats Environmental Assumptions Intended Use Functionality Security features Security services Security mechanisms selected Assurance Target-specific assurances Target-independent assurances Dependencies Internal External

Security Target Introduction: description of the target of evaluation (TOE) at three different abstraction levels Conformance: If the ST is conformant with any PPs or packages Security problem definition: Threats, Assumptions, etc. Security objectives: Extended components definition: describes components not described in Part 2 or Part 3 of CC document Security requirements: Present security objectives in standard requirements format TOE Summary specifications: How functional requirements are implemented and met and how assurance reqts. Are met Rationale: Sec Objectives Rationale, Sec. Reqts. Rationale, TOE Summary Spec. Rationale, etc. Before and during evaluation, ST states “what is to be evaluated?” After evaluation, ST states “what was evaluated?”

From CC Part 1 (of v3.1)

Classes in Common Criteria Functionality (11) Security audit (FAU) Communications (FCO) Crypto support (FCS) User data protection (FDP) Identification & Authentication (FIA) Sec. Mgmt (FMT) Privacy (FPR) Protection of trusted security functions (FPT) Resource utilization (FRU) Trusted Path (FTP) TOE Access (FTA) Assurance (10) Configuration Management Delivery and operation Development Guidance documents Life-cycle support Testing Vulnerability Assessment Maintenance of Assurance Protection profile evaluation Security target evaluation

Classes Classes are broken down into families, which are broken down into components

Classes, contd.

Components

EAL Levels EAL1: Functionally Tested EAL2: Structurally Tested; Applicable to systems with low-moderate assurance needs, but not enough development record (e.g legacy systems) Based on High-Level Design Analysis & Sec. Fn. Analysis EAL3: Methodically Tested & Checked Use of devt. Environment controls and config. Mgt EAL4: Methodically Designed, Tested & Reviewed Includes Low-level design, complete interface description, and subset of implementation Informal model of security policy Windows 2000, XP, Red Hat Enterprise Linux (RHEL) Version 4 Update 1 AS and Red Hat Enterprise Linux (RHEL) Version 4 Update 1 WS

EAL5: Semi-formally Designed and Tested EAL Levels, contd. EAL5: Semi-formally Designed and Tested EAL6: Semi-formally Verified Design and Tested EAL7: Formally Verified Design and Tested Formal functional spec. and high-level design Implementation representation be used as testing basis Independent confirmation of developer’s test results Extremely high-risk situations and requires substantial security engineering