Identity & Access Management Models

Access Control Models

  • MAC - Mandatory Access Control

    • Assigning labels to resources and accounts (objects).

    • Users and system accounts (subjects) are assigned a classification level.

    • Examples: SECRET, CONFIDENTIAL, PROPRIETARY, and PUBLIC

    • Subjects access rights must be above the objects classification.

    • Access is non-discretionary.

    • Used in Government & Military.

    • Rigid and most secure.

    • To determine if a file may be opened:

      • Compare the object and subject labels.

      • Subject must have equal or greater level than object to be granted access.

    • Two major implementations of MAC:

      • Lattice Model

        • Subjects and objects are assigned a 'rung' on the lattice.

        • Multiple lattices can be placed beside each other.

      • Bell-LaPadula Model

        • Similar to the Lattice model.

        • Subjects may not create a new object or perform specific functions on lower level objects.

    • Examples of MAC implementation:

      • Windows 7/Vista has 4 levels.

      • Specific actions by a subject with lower classification require admin approval.

  • DAC - Discretionary Access Control

    • Access rights at the discretion of the system or info owner / security principal.

    • Owner assigns security access / has flexibility in accessing info or systems.

    • Allows dynamic sharing.

    • Increased risk of unauthorized disclosure or access.

    • Least restrictive model.

    • Every object has an owner.

      • Owners have total control over their objects.

      • Owners can give permissions to other subjects over their objects.

    • DAC weaknesses:

      • Relies on decisions by end users to set proper sec levels

        • Incorrect permissions may be granted.

      • Subject's permissions will be 'inherited' by any program the subject executes.

      • Trojans are a particular problem with DAC.

  • ABAC - Attribute Based Access Control

    • Defined in NIST 800-162, Attribute Based Control Definition and Considerations

    • Attributes are characteristics that define specific aspects of the subject, object, environment conditions and/or requested actions that are predefined and preassigned by an authority.

    • Considers all of the various attributes associated with the subject and object in making the access control decision.

    • A dynamic access control method.

    • Based on the Extensible Access Control Markup Language (XACML)

  • RBAC - Role-Based Access Control

    • Access control based on established roles or job functions in an organization.

    • Group-based permissions.

    • Reduces effect of permissions creep.

    • Users or subjects are assigned roles under RBAC.

  • RBAC - Rule-Based Access Control

    • Uses the settings in preconfigured security policies to make all access decisions.

    • Rule-based access control includes controls such as the time of day, the day of the week, specific terminal access, and GPS coordinates of the requester.

    • Implemented with Access Control Lists (ACLs)

Name

Restrictions

Description

Mandatory Access Control (MAC)

End user cannot set controls.

Most restrictive model.

Discretionary Access Control (DAC)

Subject has total control over objects.

Least restrictive model.

Role Based Access Control (RBAC)

Assigns permissions to particular roles in the organization and then users are assigned to roles.

Considered a more 'real-world' approach.

Rule Based Access Control (RBAC)

Dynamically assigns roles to subjects based on a set of rules defined by a custodian.

Used for managing user access to one or more systems.

Best Practices for Access Control

  • Establishing best practices for limiting access.

    • Can help secure systems and data.

  • Examples of best practices:

    • Separation of duties.

      • Fraud can result from single user being trusted with complete control of a process.

      • Requiring two or more people responsible for functions related to handling money.

    • Job rotation.

      • System is not vulnerable to actions of a single person.

      • Employees can rotate within their department or across departments.

      • Limits amount of time individuals are in a position to manipulate security configurations.

      • Helps expose potential avenues for fraud.

        • Individuals have different perspectives and may uncover vulnerabilities.

      • Reduces employee burnout.

    • Least privilege.

      • Limiting access to information based on what is needed to perform a job function.

      • Helps reduce attack surface by eliminating unnecessary privileges.

      • Should apply to users and processes on the system.

      • Processes should run at minimum security level needed to correctly function.

      • Temptation to assign higher levels of privilege is great.

Challenge

Explanation

Legacy Applications

Many older software applications were designed to only run with a high level of privilege. Many of these applications were internally developed and are no longer maintained or are third-party applications that are no longer supported. Redeveloping the application may be seen as too costly; an alternative is to run the application in a virtualized environment.

Common Administrative Tasks

In some organizations, basic system administration tasks are performed by the user, such as connecting printers or defragmenting a disk; without a higher level of privilege, users must contact the help desk so that a technician can help with the tasks.

Software Installation/Upgrade

A software update that is not centrally deployed can require a higher privilege level, which can mean support from the local help desk; this usually results in decreased productivity and increased support costs.

  • Implicit deny.

    • If a condition is not explicitly met, access request is rejected.

    • Ex: network router rejects access to all except conditions matching the rule restrictions.

  • Mandatory vacations.

    • Limits fraud, because the perpetrator must be present daily to hide the fraudulent actions.

    • Audit of employee's activities usually scheduled during vacation for sensitive positions.

Access Control Lists (cont. from {Network Components})

  • Set of permissions attached to an object.

  • Specifies which subjects may access the object and what operations they can perform.

  • When subject requests to perform an operation:

    • System checks ACL for an approved entry.

  • ACLs usually viewed in relation to operating system files.

  • Each entry in the ACL table is called Access Control Entry (ACE).

  • ACE structure (Windows)

    • Security identifier for the user or group account or session.

    • Access mask that specifies access rights controlled by ACE.

    • Flag that indicates type of ACE.

    • Set of flags that determine whether objects can inherit permissions.

Group Policies

  • Microsoft Windows Feature

    • Provides centralized management and configuration of computers and remote users using Active Directory (AD).

    • Usually used in enterprise environments.

    • Settings stored in Group Policy Objects (GPOs)

  • Local Group Policy

    • Fewer options to configure than a Group Policy.

    • Used to configure settings for systems not part of AD.

Biometrics

  • Fingerprint Scanner

  • Retinal Scanner

  • Iris Scanner

  • Voice Recognition

  • Facial Recognition

  • Signature

  • Gait (how fast and how they walk)

  • Signature Dynamics

    • The biometric method that analyzes both the physical motions performed when a signature is signed and the specific features of a person's signature.

    • It usually captures the speed of the signing, the pressure of th epen, and the way the pen is held.

Tokens

  • Physical device used for access.

  • Software or hardware based.

  • One-Time Passwords (OTP)

    • HOTP - HMAC OTP: Uses a hash.

    • TOPT - Time-Based OTP: Limited Time Availability

  • Examples: Wireless Keycard, Key Fob, or Any Physical Device

  • Contains a digital certificate and/or static password token.

Physical Access Controls

  • Proximity Cards

    • Hold little info.

    • Determines access by matching the card ID # to access database info.

  • Smart Cards

    • Provides an authenticating crypto key to its reader.

    • May include other info on a programmable chip such as biometrics or certs.

  • Both use embedded microchips.

Certificate-Based Authentication

  • PIV/CAC/Smart Card

  • Personal Identity Verification Cards

    • Contactless smart card used by US Federal Workers

  • Common Access Card (CAC)

    • A credit card sized "smart" card used by US DoD workers.

    • Inserted into a smart card reader authenticated with a PIN.

  • IEEE 802.1x

    • Certificate based network authentication.

    • Allows only authorized devices to connect to the network.

    • Allows a company to reduce the exposure of sensitive systems to unmanaged devices on internal networks.

    • Can be used on wired networks to segment traffic intended for the WAP.

File System Security AKA "Flat Files"

  • Leverage access controls, encryption, and RAID.

  • Microsoft NTFS allows file-level access control where FAT allows only share-level access.

  • Consider using encryption for sensitive directories/media.

Database Security

  • Store organizations most sensitive / critical data.

  • Leverage network security & access controls within the Database Management System (DBMS)

  • Transparent Data Encryption (TDE) for data.

  • Crypto key management.

  • Data Control Language (DCL) - implements security through access control and granular restrictions.

Database View

  • Database security feature that provides granular access controls.

  • Used to limit user and group access to certain information based on the user privileges and the need to know.

  • Views can be used to restrict information based on group membership, user rights, and security labels.

  • Views implement least privilege and need-to-know and provide content-dependent access restrictions.

  • Views do not provide referential integrity, which is provided by constraints or rules.

  • An example of content-dependent access control in which the access control is based on the sensitivity of information and the user privileges granted.

    • This leads to higher overhead in terms of processing because the data as granularly controlled by the content and the privileges of users.

  • Can limit user access to portions of data instead of the entire database.