Unit OS7: Security Unit OS7: Security

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Unit OS7: Security Unit OS7: Security

7.1. 7.1. The Security Problem The Security Problem

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Copyright Notice Copyright Notice

These materials are part of the

These materials are part of the Windows Operating Windows Operating System Internals Curriculum Development Kit,

System Internals Curriculum Development Kit, developed by David A. Solomon and Mark E.

developed by David A. Solomon and Mark E.

Russinovich with Andreas Polze Russinovich with Andreas Polze

Microsoft has licensed these materials from David Microsoft has licensed these materials from David Solomon Expert Seminars, Inc. for distribution to Solomon Expert Seminars, Inc. for distribution to academic organizations solely for use in academic academic organizations solely for use in academic environments (and not for commercial use)

environments (and not for commercial use)

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Roadmap for Section 7.1 Roadmap for Section 7.1

The Security Problem - a Definition The Security Problem - a Definition

Program & System Threats Program & System Threats

Security Ratings

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The Security Problem The Security Problem

System is secure if its resources are utilized and access System is secure if its resources are utilized and access is as intended under all circumstances is as intended under all circumstances

Security violations:

Unauthorized reading of data (theft of information) Unauthorized reading of data (theft of information)

Unauthorized modification of data Unauthorized modification of data

Unauthorized destruction of data Unauthorized destruction of data

Security measures:

Physical Physical

User authorization User authorization

Weakness at high-level security may circumvent low- Weakness at high-level security may circumvent low- level (operating system) measures

level (operating system) measures

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Solving the Security Problem Solving the Security Problem

Access to a system (1) vs.

access to resources on a system (2) access to resources on a system (2)

(1) is solved through (1) is solved through

Authentication Authentication

Local or networked database of users Local or networked database of users

(2) is solved through (2) is solved through

Permissions Permissions

Mandatory vs. discretionary access control Mandatory vs. discretionary access control Capabilities vs. access control lists

Capabilities vs. access control lists

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Authentication Authentication

Username/password, biometric ID, smartcards Username/password, biometric ID, smartcards

Special case of keys/capabilities Special case of keys/capabilities

System generated vs. User generated passwords System generated vs. User generated passwords (hard to remember/easy to guess)

(hard to remember/easy to guess)

Paired passwords: system selects one/user responds Paired passwords: system selects one/user responds appropriately

appropriately

How to store passwords securely How to store passwords securely

one-way functions executed on passwords one-way functions executed on passwords

easy to calculate but hard to invert easy to calculate but hard to invert

Shadow passwords Shadow passwords

restricted access to password files restricted access to password files

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Security Ratings & Windows NT Security Ratings & Windows NT

Windows NT was designed to be secure from the start, which meant Windows NT was designed to be secure from the start, which meant aiming at achieving a security rating from a recognized rating

aiming at achieving a security rating from a recognized rating system

system

In 1981 the National Computer Security Center (NCSC In 1981 the National Computer Security Center (NCSC www.radium.

www.radium.nscnsc.mil/.mil/tpeptpep) was established as part of the US DoD’s ) was established as part of the US DoD’s NSA to help government, corporations and home users protect

NSA to help government, corporations and home users protect proprietary, confidential information

proprietary, confidential information

Part of the goal was to create security ratings, also known as the Part of the goal was to create security ratings, also known as the

“Orange Book”, which were defined in 1983

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A1A1 Verified DesignVerified Design B3B3 Security DomainsSecurity Domains

B2B2 Structured Protection (Trusted XENIX)Structured Protection (Trusted XENIX)

B1B1 Labeled Security Protection (HP-UX, Trusted Labeled Security Protection (HP-UX, Trusted IRIX, Tru64 UNIX)

IRIX, Tru64 UNIX)

C2C2 Controlled Access Protection (highest level Controlled Access Protection (highest level considered practical for general purpose OS) considered practical for general purpose OS) C1C1 Discretionary Access Protection (obsolete)Discretionary Access Protection (obsolete) DD Minimal Protection (e.g. DOS)Minimal Protection (e.g. DOS)

Security Ratings

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Windows Security Support Windows Security Support

Microsoft’s goal was to achieve C2, which Microsoft’s goal was to achieve C2, which

requires:

Secure Logon: NT provides this by requiring user name and Secure Logon: NT provides this by requiring user name and

password password

Discretionary Access Control: fine grained protection over Discretionary Access Control: fine grained protection over

resources by user/group resources by user/group

Security Auditing: ability to save a trail of important security Security Auditing: ability to save a trail of important security

events, such as access or attempted access of a resource events, such as access or attempted access of a resource

Object reuse protection: must initialize physical resources that Object reuse protection: must initialize physical resources that

are reused e.g. memory, files are reused e.g. memory, files

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Windows Certification Windows Certification

Certifications achieved:

Windows NT 3.5 (workstation and server) with SP3 earned C2 in Windows NT 3.5 (workstation and server) with SP3 earned C2 in

July 1995 July 1995

In March 1999 Windows NT 4 with SP3 earned e3 rating from In March 1999 Windows NT 4 with SP3 earned e3 rating from

UK’s Information Technology Security (ITSEC) – equivalent to C2 UK’s Information Technology Security (ITSEC) – equivalent to C2 In November 1999 NT4 with SP6a earned C2 in stand-alone and In November 1999 NT4 with SP6a earned C2 in stand-alone and

networked environments networked environments

Windows meets two B-level requirements:

Trusted Path Functionality: way to prevent trojan horses with Trusted Path Functionality: way to prevent trojan horses with

“secure attention sequence” (SAS) - Ctrl-Alt-Del

Trusted Facility Management: ability to assign different roles to Trusted Facility Management: ability to assign different roles to

different accounts different accounts

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Common Criteria Common Criteria

New standard, called Common Criteria (CC), is the new standard for New standard, called Common Criteria (CC), is the new standard for software and OS ratings

software and OS ratings

Consortium of US, UK, Germany, France, Canada, and the Netherlands Consortium of US, UK, Germany, France, Canada, and the Netherlands in 1996

in 1996

Became ISO standard 15408 in 1999 Became ISO standard 15408 in 1999 For more information, see

For more information, see http://http://www.commoncriteriaportal.orgwww.commoncriteriaportal.org// and and http://

http://csrc.nist.govcsrc.nist.gov/cc/cc

CC is more flexible than TCSEC trust ratings, and includes concept of CC is more flexible than TCSEC trust ratings, and includes concept of Protection Profile to collect security requirements into easily specified Protection Profile to collect security requirements into easily specified and compared sets, and the concept of Security Target (ST) that

and compared sets, and the concept of Security Target (ST) that

contains a set of security requirements that can be made by reference contains a set of security requirements that can be made by reference to a PP

to a PP

Windows 2000 was certified as compliant with the CC Controlled Windows 2000 was certified as compliant with the CC Controlled Access Protection Profile (CAPP) in October 2002

Access Protection Profile (CAPP) in October 2002

Windows XP and Server 2003 are undergoing evaluation Windows XP and Server 2003 are undergoing evaluation

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A Note About Physical Security A Note About Physical Security

Windows is definitely

Windows is definitely not secure if someone has physical access:not secure if someone has physical access:

At the minimum they can destroy data At the minimum they can destroy data

They can easily gain access to FAT/FAT32 files (by booting DOS) They can easily gain access to FAT/FAT32 files (by booting DOS) They can gain access to NTFS files with NTFSDOS or ERD

They can gain access to NTFS files with NTFSDOS or ERD Commander (or free Linux-based tools)

Commander (or free Linux-based tools)

Encryption (like EFS) is the only way to secure data on systems that can Encryption (like EFS) is the only way to secure data on systems that can have compromised physical security (like laptops)

have compromised physical security (like laptops)

On Windows 2000, must encrypt with domain credentials On Windows 2000, must encrypt with domain credentials

On Windows XP & higher, the local administrator account is no longer a recovery On Windows XP & higher, the local administrator account is no longer a recovery agent

agent

Since credentials are cached and can be cracked, must remove SAM's Since credentials are cached and can be cracked, must remove SAM's encryption key from system (use syskey level 1 or 2)

encryption key from system (use syskey level 1 or 2)

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Unit OS7: Security Unit OS7: Security