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10a Access control
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1Access control defines and [blank_start]enforces[blank_end] the [blank_start]operations[blank_end] that [blank_start]subjects[blank_end] can do on [blank_start]objects[blank_end].
eg. does bob ([blank_start]subject[blank_end]) have the permission to read ([blank_start]operation[blank_end]) from a socket ([blank_start]object[blank_end])- Aenforces
- Boperations
- Csubjects
- Dobjects
- Esubject
- Foperation
- Gobject
2[blank_start]Access rights[blank_end] (permissions, [blank_start]privileges[blank_end]) describe which [blank_start]subject[blank_end] can do which [blank_start]operation[blank_end] on which [blank_start]objects[blank_end].
ex. [blank_start]security policy[blank_end] that can be represented as an access control matrix- AAccess rights
- Bprivileges
- Csubject
- Doperation
- Eobjects
- Fsecurity policy
3[blank_start]security mechanism[blank_end] try to prevent [blank_start]operations[blank_end] that are not authorised by the security [blank_start]policy[blank_end].
- Asecurity mechanism
- Boperations
- Cpolicy
4Principle of least privilege:
- Asubject should have minimum rights necessary to do their job
- Blimits the impact if anything goes wrong
- Cleast important access control
- Dthere is a one-size-fits all solution in access control
5Multiple level of access control:
- Network level access control:
Subjects: [blank_start]connections[blank_end] or [blank_start]data packets[blank_end]
Id of subjects: src/dest [blank_start]IP[blank_end], protocol [blank_start]port[blank_end]
Operations: [blank_start]pass[blank_end], [blank_start]block[blank_end], tag
Network equipment: [blank_start]Firewalls[blank_end] / Local [blank_start]firewalls[blank_end] in server / [blank_start]configuration[blank_end] on server software.- Aconnections
- Bdata packets
- CIP
- Dport
- Epass
- Fblock
- GFirewalls
- Hfirewalls
- Iconfiguration
6Operating system access control:
Subjects: [blank_start]users[blank_end]
Operations: [blank_start]read[blank_end], w[blank_start]rite[blank_end], m[blank_start]odify[blank_end], [blank_start]start[blank_end]/stop DB
Objects: [blank_start]Files[blank_end] in DB, DB [blank_start]engine[blank_end]- Ausers
- Bread
- Crite
- Dodify
- Estart
- FFiles
- Gengine
7What are the 3 types of access control?
A) RBAC => [blank_start]role-based[blank_end] access control
B) DAC => [blank_start]discretionary[blank_end] access control
C) MAC => [blank_start]mandatory[blank_end] access control- Arole-based
- Bdiscretionary
- Cmandatory
8Fill the blanks.
Role-based access control
- Ausers
- Brights
- Cusers
- Droles
- Erights
9How to implement RBAC?
- Java:
-- Java authentication and authorization service (JAAS)
-- Uses [blank_start]policy file[blank_end] to define permissions
- OS:
-- [blank_start]User groups[blank_end]
-- Group can be given set of [blank_start]permissions[blank_end]
-- [blank_start]User[blank_end] can be added to [blank_start]groups[blank_end]- AUser
- Bgroups
- Cpermissions
- DUser groups
- Epolicy file
10Advantages of RBAC:
- Easy to grasp the idea of roles
- Easy to [blank_start]manage[blank_end]:
-- Role [blank_start]decouple[blank_end] [blank_start]entities[blank_end] from [blank_start]permissions[blank_end]
-- No need to decide for each [blank_start]resource[blank_end] when you can simply assign the role
-- Easy to [blank_start]revoke[blank_end] role
- Easy to be [blank_start]centrally[blank_end] managed- Acentrally
- Brevoke
- Cmanage
- Ddecouple
- Eentities
- Fpermissions
- Gresource
11Disadvantages of RBAC
- Difficult to decide on the [blank_start]granularity[blank_end] of roles
- Meaning of role is fuzzy : [blank_start]employee position[blank_end] != RBAC role (engineer on different subjects)
- Unclear if role can be [blank_start]shared across[blank_end] department- Agranularity
- Bemployee position
- Cshared across
12Discretionary Access control:
Access control is at the [blank_start]discretion[blank_end] of the [blank_start]object[blank_end] [blank_start]owner[blank_end].
> Owner specifies [blank_start]policies[blank_end] to [blank_start]access[blank_end] resources it [blank_start]owns[blank_end].- Adiscretion
- Bobject
- Cowner
- Dpolicies
- Eaccess
- Fowns
13What is the row & column of an access control matrix of the discretionary access control?
Stud1 - Row: _____________ by ______________
/stud/grades.txt - Col: ______ stored with resource
- Acapabilities by subject
- Baccess control list
14Access control list (ACL):
- [blank_start]knows[blank_end] exact who can get in
- users [blank_start]don't know[blank_end] if they can get in- Aknows
- Bdon't know
15Role-based access control:
> centered on [blank_start]users[blank_end] [blank_start]roles[blank_end]
> a role can contain [blank_start]multiple[blank_end] [blank_start]permissions[blank_end]
- Ausers
- Broles
- Cmultiple
- Dpermissions
16Capabilities (key):
- doors [blank_start]don't know[blank_end] who will show up with a key
- people [blank_start]knows[blank_end] exactly what they can open- Adon't know
- Bknow
17Role-based access control:
> Centered on [blank_start]user[blank_end] [blank_start]roles[blank_end]
> a role can contain [blank_start]multiple[blank_end] [blank_start]permissions[blank_end]- Apermissions
- Bmultiple
- Croles
- Duser
18When Jane runs passwd, the process is run as [blank_start]root[blank_end].
> if a program has [blank_start]setuid[blank_end] bit set, it will run with permissions of the [blank_start]owner[blank_end] instead of the permission of the [blank_start]user[blank_end] running the program.
> the [blank_start]setgid[blank_end] bit does the same for user groups.
> these bits are displayed as [blank_start]s[blank_end] instead of [blank_start]x[blank_end] in access rights of the file
- Ax
- Bs
- Csetgid
- Dsetuid
- Eroot
- Fowner
- Guser
19The s represent....
- Asetuid
- Bsetgid
20> passwd can be read by [blank_start]all[blank_end] but only modified by [blank_start]root[blank_end]
> shadow can be read by [blank_start]root[blank_end] and [blank_start]shadow[blank_end] and modified by [blank_start]root[blank_end]
- Aall
- Broot
- Croot
- Dshadow
- Eroot
21ACLs in Unix:
- Three access rights: [blank_start]read[blank_end] (r), [blank_start]write[blank_end] (w), [blank_start]execute[blank_end] (x)
- [blank_start]3[blank_end] rights and 3 [blank_start]groups[blank_end] stored in [blank_start]9[blank_end] bits:
> [blank_start]owner[blank_end] rwx, [blank_start]group[blank_end] rwx, [blank_start]others[blank_end] rwx- Aowner
- Bgroup
- Cothers
- D3
- Egroups
- Fread
- Gwrite
- Hexecute
- I9
22Setuid can be dangerous because of possible [blank_start]priviledge[blank_end] [blank_start]escalation[blank_end] (HW1).
1. Find program with setuid
2. Stack overflow to use the script to run another program.- Apriviledge
- Bescalation
23The Windows administrator account has the highest privilege account.
- ATrue
- BFalse
24Capabilities in Windows:
- Windows has [blank_start]privileges[blank_end] that act like capabilities:
> setTimeZonePriviledge: can change timezone
- can check your privilege with [blank_start]whoami[blank_end] /[blank_start]priv[blank_end]- Awhoami
- Bpriv
- Cprivileges
25DAC Procs and Cons.
Select the ones that are pros.- ADAC is flexible
- BDAC depends on the owners judgement.
- CDAC works if programs are not malicious and users make no mistakes.
- DDAC is easy to manage, since owners set the permissions themselves.
- EDAC is intuitive.
- FDAC is vulnerable to Trojan problem: a malicious program run by an authorised user can read a protected file and write an unprotected copy of that file => anyone can read that file.
26Mandatory access control tries to ensure that [blank_start]even[blank_end] someone with [blank_start]access[blank_end] [blank_start]cannot[blank_end] [blank_start]leak[blank_end] data.
- Aeven
- Baccess
- Ccannot
- Dleak
27The multilevel security of mandatory access control are:
- u[blank_start]nclassified[blank_end]
- c[blank_start]onfidential[blank_end]
- s[blank_start]ecret[blank_end]
- [blank_start]top[blank_end]-[blank_start]secret[blank_end]- Asecret
- Btop
- Cecret
- Donfidential
- Enclassified
28In mandatory access control, the [blank_start]system[blank_end] labels both the [blank_start]subjects[blank_end] and [blank_start]objects[blank_end] with [blank_start]security[blank_end] [blank_start]labels[blank_end] that can only be [blank_start]modified[blank_end] by trusted administrators via trusted software.
- Asystem
- Bsubjects
- Cobjects
- Dsecurity
- Elabels
- Fmodified
29In Linux, capabilities are permissions related to a [blank_start]subject[blank_end].
- Asubject
30What is much safer than using setuid?
- Auser group instead of owner that run
31Why is a bad idea to allow secret subjects to write confidential documents?
Because then the information will [blank_start]leak[blank_end].
ex. Trump writes on newspaper.- Aleak
32MAC can be conjuncted with DAC or RBCA.
- ATrue
- BFalse
33Mandatory access control depends on [blank_start]admins[blank_end] for:
- keeping the system in a [blank_start]protected[blank_end] state
- preventing operations that [blank_start]violate[blank_end] the rules of the matrix
- labelling new [blank_start]subjects[blank_end] and [blank_start]objects[blank_end]
- perform transitions of [blank_start]labels[blank_end]- Aadmins
- Bprotected
- Cviolate
- Dsubjects
- Eobjects
- Flabels
34DAC addresses the limitations of MAC.
- ATrue
- BFalse
35MAC and Confidentiality
When protecting [blank_start]confidentiality[blank_end], we don't want users of high level to write to a lower level ([blank_start]no[blank_end] [blank_start]write[blank_end]-[blank_start]down[blank_end])
> prevents [blank_start]leaking[blank_end] from higher to lower level
> ex. network access control : internet - internal - secret. Information can only flow from lower to higher level.- Aconfidentiality
- Bno
- Cwrite
- Ddown
- Eleaking
36MAC and [blank_start]integrity[blank_end]
We don't want users from lower level to write into higher level ([blank_start]no[blank_end] [blank_start]write[blank_end]-[blank_start]up[blank_end])
> prevents unauthorised [blank_start]modification[blank_end] to objects
> ex. OS
- user can read and execute programs in OS, but they cannot modify them.- Amodification
- Bwrite
- Cup
- Dno
- Eintegrity
37MAC pros and cons
:) addresses the limitations of [blank_start]DAC[blank_end]
:) easy to [blank_start]scale[blank_end]
:( [blank_start]restrict[blank_end] too much, prevent legitimate tasks
:( [blank_start]not flexible[blank_end]- ADAC
- BRBAC
- Cscale
- Dshrink
- Erestrict
- Fcontrol
- Gnot flexible
- Htoo flexible
38Modern os make use of these types:
- [blank_start]DAC[blank_end] with [blank_start]ACL[blank_end] for files and most objects
- [blank_start]DAC[blank_end] with [blank_start]capabilities[blank_end] for privileged operations
- Using [blank_start]groups[blank_end] to implement RBAC (users, admins, HR, marketing)
- [blank_start]MAC[blank_end] for protecting the integrity of the system- ADAC
- BMAC
- CRBAC
- DACL
- EDAC
- FMAC
- GDAC
- HMAC
- IRBAC
- Jcapabilities
- KACL
- LRBAC
- Mgroups
- Nusers
- Oadmins
- PMAC
- QDAC
- RACL
39MAC in windows.
Windows implements MAC for [blank_start]integrity[blank_end] protection (Mandatory [blank_start]Integrity[blank_end] Control).
4 levels: low, [blank_start]medium[blank_end], high, [blank_start]system[blank_end]
Objects have a label that says whether write-[blank_start]up[blank_end], read-[blank_start]up[blank_end], or execute-[blank_start]up[blank_end]
ex. Words in protected view run in low integrity level. They can only write to directories of low integrity level.- Aintegrity
- BIntegrity
- Cmedium
- Dsystem
- Eup
- Fup
- Gup
40Some linux programs setguid (group) shadow because:
they need to access to the password [blank_start]expiration[blank_end] date, but they do not need to see the password. So Shadow permits to [blank_start]read[blank_end] but not change the file.- Aread
- Bexpiration
41The most important principle of access control is the [blank_start]principle[blank_end] [blank_start]of[blank_end] [blank_start]least[blank_end] [blank_start]privilege[blank_end].
- Aprinciple
- Bof
- Cleast
- Dprivilege
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- - Information security (10 Access control, Authentication & protocols) Quiz on 10a Access control, created by Yawen Hou on 04/06/2019.
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- Yawen Hou
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