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Lecture Chapter 4 - Access Control Role-based models RBAC presentation of content: Role-based models, role based access control, administrative role-based access control model.
hapter 4 Access Control Rolebased models RBAC Agenda Rolebased models Administrative rolebased access control model https://books.google.com.vn/books? id=_O7xBwAAQBAJ&pg=PA171&lpg=PA171 &dq=Open/close+policy+in+database+security &source=bl&ots=4cH6efHzHp&sig=eO6djffm piyvB0L6hmWAbPPeZow&hl=vi&sa=X&ei= F2PVb YOcaJuATyvIHQAw&redir_esc=y#v=onepage &q&f=false Rolebased models Many organizations base access control decisions on “the roles that individual users take on as part of the organization” They prefer to centrally control and maintain access rights that reflect the organization’s protection guidelines With RBAC, rolepermission relationships can be predefined, which makes it simple to assign users to the predefined roles. The combination of users and permissions tend to change over time, the permissions associated with a role are more stable RBAC concept supports three wellknown security principles: – Least privilege – Separation of duties – Data abstraction Role Based Access Control (RBAC) Access control in organizations is based on “roles that individual users take on as part of the organization” A role is “is a collection of permissions” Roles Hierarchies Users User Role Assignment Roles Constraints Role Permission Assignment Permissions Role Based Access Control (RBAC) RBAC Access depends on role/function, not identity – Example: Allison is bookkeeper for Math Dept. She has access to financial records. If she leaves and Betty is hired as the new bookkeeper, Betty now has access to those records. The role of “bookkeeper” dictates access, not the identity of the individual RBAC Users Permission Users Permissions u1 o1 u1 o1 o2 u2 o2 om un om Manager Senior Administrator Senior Engineer Administrator Engineer Employee u2 Role r un n + m assignments n m assignments (a) (b) RBAC (cont’d) Is RBAC a discretionary or mandatory access control? – RBAC is policy neutral; however individual RBAC configurations can support a mandatory policy, while others can support a discretionary policy Role Hierarcies Role Administration Project Supervisor Test engineer Programmer Project Member RBAC (NIST Standard) PA UA Users Roles Operations Objects Permissions user_sessions (one-to-many) role_sessions (many-to-many) Sessions An important difference from classical models is that Subject in other models corresponds to a Session in RBAC Core RBAC (relations) Permissions = 2Operations x Objects UA ⊆ Users x Roles PA ⊆ Permissions x Roles assigned_users: Roles 2Users assigned_permissions: Roles 2Permissions Op(p): set of operations associated with permission p Ob(p): set of objects associated with permission p user_sessions: Users 2Sessions session_user: Sessions Users session_roles: Sessions 2Roles – session_roles(s) = {r | (session_user(s), r) UA)} avail_session_perms: Sessions 2Permissions RBAC with General Role Hierarchy RH (role hierarchy) PA UA Users Roles user_sessions (one-to-many) Sessions Operations Objects Permissions role_sessions (many-to-many) RBAC with General Role Hierarchy authorized_users: Roles 2Users authorized_users(r) = {u | r’ ≥ r &(r’, u) UA) authorized_permissions: Roles 2Permissions authorized_users(r) = {p | r’ ≥ r &(p, r’) PA) RH Roles x Roles is a partial order – – called the inheritance relation written as ≥. (r1 ≥ r2) authorized_users(r1) ⊆ authorized_users(r2) & authorized_permisssions(r2) ⊆ authorized_permisssions(r1) Example px, e10 py e8, px, e9 py Manager px, e5py Senior Administrator pa, pb Administrator px, py e3, px, e4 py e1, px, e2 py Employee p1, p2 pp Senior Engineer e6, px, e7 py po Engineer pm, pn authorized_users(Employee)? authorized_users(Administrator)? authorized_permissions(Employee)? authorized_permissions(Administrator)? Constrained RBAC RH (role hierarchy) Static Separation of Duty PA UA Users Roles Operations Objects Permissions user_sessions (one-to-many) Sessions Dynamic Separation of Duty Separation of Duties § No user should be given enough privileges to misuse the system on their own § Statically: defining the conflicting roles § Dynamically: Enforcing the control at access time Role vs. Types Data Structures RBAC – – – U: set of users P: set of permissions R: set of roles Type Enforcement – – E: set of subjects or objects Permission Assignment ST: set of subject types OT: set of object types O: set of operations Role vs. Types Data Structures Users: U Permissions: P Roles: R Assignments: Userrole, permrole, role role Sessions: S Function: user(S), roles(S) Constraints: C RBAC Family of Models RBAC0 contains all but hierarchies and constraints RBAC1 contains RBAC0 and hierarchies RBAC2 contains RBAC0 and constraints RBAC3 contains all The RBAC family idea has always been more a NIST initiative The RBAC families are present in the NIST RBAC standard [NIST2001] with slight modifications: – RBAC0, RBAC1 (options), RBAC3 (SSD) , RBAC3 (DSD) Advantages of RBAC Allows Efficient Security Management – Administrative roles, Role hierarchy Principle of least privilege allows minimizing damage Separation of Duties constraints to prevent fraud Allows grouping of objects Policyneutral Provides generality Encompasses DAC and MAC policies RBAC’s Benefits Cost Benefits Saves about 7.01 minutes per employee, per year in administrative functions – – Average IT admin salary $59.27 per hour The annual cost saving is: • $6,924/1000; $692,471/100,000 Reduced Employee downtime – – – if new transitioning employees receive their system privileges faster, their productivity is increased 26.4 hours for nonRBAC; 14.7 hours for RBAC For average employee wage of $39.29/hour, the annual productivity cost savings yielded by an RBAC system: • $75000/1000; $7.4M/100,000 RBAC Products SUN Solaris Sybase SQL Server BMC INCONTROL for Security Management Systor Security Administration Manager Tivoli TME Security Management Computer Associates Protect IT Siemens rbacDirX ... Many organizations base access control decisions on “the roles that individual users take on as part of the organization” They prefer to centrally control and maintain access rights that reflect ... RBAC concept supports three wellknown security principles: – Least privilege – Separation of duties – Data abstraction Role Based Access Control (RBAC) Access control in organizations is based on “roles that individual users take on as ... Assignment Permissions Role Based Access Control (RBAC) RBAC Access depends on role/function, not identity – Example: Allison is bookkeeper for Math Dept. She has access to financial records. If she