Download Enhanced Security Models for Operating Systems: A Cryptographic

Presented by
Gopi Krishna V
Contents
 Introduction
 Security features of Trusted system
 Problems with Trusted systems
 Vaults Model
 Protection Mechanism
 Advantages of Vault
 Conclusion
Introduction
Computer Security problem:
 Earlier, many approaches have been tried in order to provide
security in use of computing resources, but we have only limited
success.
 Why is this situation actually getting worse?
Reason: Increased use of distributed computing resources across
insecure networks and unpredicted run time interactions cause
hard to detect security flaws.
 Many operating system security features developed earlier, which
have largely been ignored in the contemporary systems
Introduction
Importance of Host Security:
 Protection mechanisms can be easily bypassed if
an attacker can gain access to the layer below that
where the protection mechanism resides.
 Not only developing secure network protocols but
also provision of sufficiently secure operating
system.
Introduction
Importance of Host Security:
 Protection mechanisms can be easily bypassed if
an attacker can gain access to the layer below that
where protection mechanism resides.
 Not only developing secure network protocols but
also provision of sufficiently secure operating
system.
 For sufficient secure foundation , lets have a look
at Trusted Systems.
Security features of Trusted System
 Trusted systems are identified by two key features for
the provision of strong security.
 Mandatory Security
 Trusted path
Security features of Trusted System
Mandatory security:
 Nowadays, the majority of systems use Discretionary access
control (DAC) where each user determines security policy.
 However, Mandatory Access control(MAC) involves a
“security administrator” who determines security policy.
Trusted path:
 It is a mechanism, where a user can interact directly with
security-critical system components in an authenticated
manner that cannot be imitated by malicious software.
Problems with trusted systems
Problems:
 Documenting, developing, deploying and testing are
significant costs.
Vaults Model
 Incorporating cryptography into the security
infrastructure by operating system kernel.
 This infrastructure can be separated into two types.


Repository parts(Vaults).
protection mechanisms.
Vaults Model
Vaults:
 A vault is simply a data structure holding sensitive data
to which the security kernel carefully controls access
according to a small set of simple, pre-defined rules.
 Five different types of vaults





User vaults
Global Private Vault (GPRIV)
Global Public Vault(GPUV)
Escrow Vault
Fundamental Vault
Vaults Model
User Vaults:
 Each user on the system has their own vault, where user
can store data virtually and retrieved whenever user
required.
Global Private Vault(GPRIV):
 GPRIV is the system-wide equivalent of the user vaults.
Only the system kernel is able to directly access GPRIV.
Global public vaults(GPUV):
 GPUV is opposite to GPRIV in that it holds values that
must be accessible by all users on the system as required.
Vaults Model
Escrow vaults:
 It is similar to GPRIV vault.
 It is used to hold keys for protected objects such that
they can be retrieved if required by the Security
administrator.
Fundamental Vaults:
 The fundamental vaults are used to hold the keys for
encrypting the other four vaults.
Protection Mechanism
File Protection:
 Protection of file system objects is one of the key security functions of
any OS.
 Vaults provide protection to both read and write operations.
Read and Write protection:
 Now a days, cryptographic file systems only provide confidentiality.
Writing into encrypted file is difficult.
 Vaults provide file protection keys, where it can provide confidentiality
and integrity.
 Message Authentication code(MAC) used to access write permission
Ticket and File sharing:
 Tickets grant permissions to select users and to access objects using a
token.
 Owner of the object creates protections(read/write),where token and
key are generated and stored in the GPRIV.
Protection Mechanism
Trusted Fingerprinting:
 Under Vault architecture, System administrator uses
fingerprinting to protect themselves against threats.
 Two types of fingerprinting:


Global Fingerprinting
Local Finger printing
Protection mechanism
Global Fingerprinting:
 Global fingerprinting stores all authorized users’ finger
print in GPUB.
 Whenever any user tries to execute a program file, the
kernel checks the particular user fingerprint in GPUB. If it
matches the fingerprint, it allows the execution.
 There are three main advantages
 It will check integrity of the program at the time of execution.
 It removes the dependency static integrity checker on unsecured
components.
 It prevents users from running modified program.
Protection Mechanism
Local fingerprinting:
 It provides the security to individual user.
 Vaults allow individual users to accumulate
fingerprints of the software .
 It provides own security needs in their vault.
 This means, it allows a user to implement their own
policy.
Protection Mechanism
Dual TCB and Extensible Trusted Path:
 Trusted Computing Base(TCB) collection of
components responsible for enforcing security
policy.
 Dual TCB
 Global TCB
 Local TCB
 Global TCB handles components in system security with
fingerprints in GPUB.
 Local TCB handles components of individual user fingerprint in
their own vault.
Advantages of Vault
Strong security :
 Vaults provide a strong security baseline similar to
mandatory security features in trusted system.
 Vaults implements Trusted finger print
mechanism.
Flexible and Intuitive security:
 Providing more flexibility by offering own security
as needed.
 The dual TCB prevents undetected modifications
of the program
Advantages of vaults
Advantages over conventional system:
 It provides shield to users to get protected from
maliciously modified trusted code.
Security advantages of Cryptography:
 It eliminates the complexity and easily tested.
Conclusion
 Vaults provide a significant usability advantage, in that
users no longer need to manage and memorize a large
number of passwords and keys.