CHAPTER 11
MICROSOFT WINDOWS 2000 SECURITY
Lesson 1:
Public Key Infrastructure
Public key cryptography is a critical technology for e-commerce, intranets, extranets, and other
Web-enabled applications.
The Windows 2000 operating system includes a native public key infrastructure (PKI) that is
designed from the ground up to take full advantage of the Windows 2000 security architecture.
Security Properties
Computer security includes everything from the physical computing environment to the software
environment. In a software environment, security should
provide four functions: authentication,
integrity, confidentiality, and
anti-replay.
1. Authentication
Authentication is the process or reliably determining the genuine identity of the communicating
computer (host) or user. Authentication is based on cryptography, it ensures that an attacker
eavesdropping on the network cannot gain the information needed to impersonate a valid user
or entity.
2. Integrity
Integrity is the correctness of data as it was originally sent. Integrity services protect data from
unauthorized modification in transit. Without data integrity, any data and the host it is sent from
is suspect.
3. Confidentiality
Confidentiality ensures that data is disclosed only to intended recipients.
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4. Anti-Replay
Anti-replay, also called replay prevention, ensures that datagrams are not retransmitted. Each
datagram sent is unique. This uniqueness prevents attacks in which a message is intercepted and
stored, then re-used later to attempt illegal access to information.
Cryptography
Cryptography is a set of mathematical techniques for encrypting and decrypting data so it can be
transmitted securely and not be interpreted by unauthorized parties. Cryptography uses keys in
conjunction with algorithms to secure data.
A key is a value used to encrypt or decrypt information. Even if the algorithm is publicly known,
security is not compromised because the data cannot be read without the key. Even if the algorithm
is publicly known, security is not compromised because the data cannot be read without the key.
For example, the algorithm of a combination lock is common knowledge: the dials are moved in a
specific order to open the lock. However, the key to the lock -- the numbers of the combination
CODE – is secret an known only to the person with the combination.
The algorithm provides the infrastructure in which the key is applied. Security systems can be
based on public key or secret key cryptographic algorithms:
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Algorithm Description
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Rivest, Shamir A general purpose algorithm that can support digital
Adleman (RS) signatures, distributed authentication, secret key
Agreement via public key, a bulk data encryption
Without prior shared secrets.
Digital Signature A public key algorithm, used for digital signatures.
Standard (DSA)
Diffie-Hellman A public key cryptography algorithm that allows two
Communicating entities to agree on a shared key
Without requiring encryption during the key generation.
Hash Message A secret key algorithm that provides integrity,
Authentication authentication, and anti-reply. A hash is also known as
Code (HMAC) a message digest.
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HMAC-Message A hash function that produces a 160-bit digital
Digest function 5 signature and that is used for authentication, integrity,
(MD5) and anti-relay.
Data Encryption A secret key algorithm used for confidentiality. A
Standard-Cipher random number is generated and used with the secret
Chaining key to Block encrypt data.
(DES-CBC)
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Public Key Cryptography
Public key cryptography is an asymmetric scheme that uses a pair of keys for encryption. It is called
asymmetric because it uses two encryption keys that are mathematically related. These related keys
are called the public and private key pair. To use public key encryption, an object (such as a user)
must generate a public and private key pair. Objects obtain public keys in one of two ways:
Domain Name System (DNS).
A public and private key pair are
typically used for two purposes: data encryption and digital
message singing.
1. Data Encryption
Data encryption provides confidentiality by ensuring that only the intended recipient is able to decrypt
and view the original data. When secure data must be transmitted, the sender obtains the recipient’s
public key. The sender then uses the recipient’s public key to encrypt data and then send it. When
the recipient receives the data, the recipient uses his or her own private key to decrypt the data.
Encryption is only secure if the sender uses the recipient’s
public key for encryption. If a sender
uses his or her private key to encrypt data,
anyone can capture the data and decrypt it by
obtaining the sender’s public key.
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2. Digital Message Signing
When a sender signs a message, a message digest is created. A message digest is a representation
of the message and is similar to a cyclic redundancy check (CRC).
The recipient then creates a message digest from the message and compares the message digest to
the decrypted message digest. If the message digests match, integrity is guaranteed.
Authentication is provided through the key pair. Since the message digest was encrypted by using
the sender’s private key (and only the sender’s public key will decrypt the message digest), the
recipient can be certain that the message came from the owner of the key pair.
The recipient, however, must have a mechanism for ensuring that the key pair belongs to the intended
sender and not someone impersonating the sender.
This is don through a certificate issued by a trusted third party, which confirms the identity of the
owner of the public key. The
trusted third party is known as a Certificate Authority (CA).
Secret Keys
A secret key (also known as shared secret or shared secret key) is used in much the same way as a
public key; however, there is only one key that provides security.
NOTE: An eavesdropper is someone using a network-monitoring tool to capture packets on the
network.
Secret Key Exchange
A common solution to providing the secret key to both parties is using public keys. Public keys
make it possible to encrypt the secret key as it is sent across the network. Public keys ensure
confidentiality, authentication, and integrity; therefore, security is not compromised when a secret
key is sent.
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Data Encryption
In order to provide confidentiality, the data must be encrypted by suing the shared secret key.
Because there is only one key known to both the sender and the receiver, encryption is a
straightforward process. The
sender and the receiver generally discard shared secret keys once
the session has been terminated.
Certificates
A digital certificate, also referred to simply as a certificate, is a set of data that completely identifies
an entity. A trusted Certificate Authority (CA) issues certificates after the authority has verified the
entity’s identity. The CA provides a trusted third party for both communicating parties.
X.509
The Windows 2000 certificate-based processes use the X.509 standard. Because it is possible
to use certificates for different applications (for example, secure e-mil, file system encryption),
each certificate has different information contained within it. However, certificates should, at a
minimum, contain the following attributes:
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Certificate Revocation Lists
The CA can also revoke them for other reasons. In order to handle the existence of invalid
certificates, the CA maintains a certificate revocation list (CRL). The CRL is available to
network users to determine the validity of any given certificate. A great example can be a
Credit Bureau. Before you do business with a company, you go to a third party business
and ask them if this company has a good standing within the community.
CAs are on the Internet, and you can check with them first.
CA Hierarchy
Rather than having one trusted CA provide authentication for the entire Internet or Intranet,
it is possible to have CAs certify other CAs. This hierarchical structure, calling chaining,
allows users to trust a single CA rather than having to trust all CAs. This chaining of
CAs provides several benefits:
organization.
The CA at the top of the chain is referred to as the root CA. CAs below the root are
referred to as intermediate, subordinate, or issuing CAs.
Microsoft Certificate Services
This enables an organization to manage the issuance, renewal, and revocation of digital
certificates without having to rely on external certificate authorities. In addition, Certificate
Services logs all transactions, enabling the administrator to track, audit, and manage certificate requests.
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Certificate Services Features
Microsoft Certificate Services has a number of features that make it valuable to organizations
that do not choose to rely upon external certificate authorities and who require a flexible tool
that can be adapted to the needs of their organization.
Policy
In order to obtain a certificate, requesters must meet certain criteria.
Policies are implemented in policy components that can be written in Java, Visual Basic, or
Microsoft C/C++. The default policy for Certificate Services allow users to request
certificates through an HTML page. Policies are usually written initially and altered by Programmers.
Transport
Certificate Services can request and distribute certificates through any transport mechanism.
That is, it can accept certificate requests from an applicant and post certificates to the applicant
through Hypertext Transfer Protocol (HTTP), remote procedure call (RPC), disk file, or custom
transport. NOTE: Disk file, was similar to the example Mr. E. did in class where he put it on
the diskette, and transferred it to
Adherence to Standards
Microsoft Certificate Services can perform the following services:
Key Management
The security of a certification system depends on the protection of private keys. The design of
Certificate Services ensures that individuals cannot access private keys information without
authorization.
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Certificate Services Architecture (only quick review)
Certificate Services architectural elements include the server engine that handles certificate
requests and other modules that perform tasks by communicating with the server engine.
(see page 630).
Server Engine
The core component of Certificate Services. The engine acts as a broker for all requests it
receives from the entry modules, driving the flow of information between components
during the processing of a request and generation of a certificate.
Intermediary
This receives new certificate request from clients and submits them to the server engine.
Microsoft Internet Information Services (IIS) is an intermediary application that provides
support for clients over HTTP.
Server Database
They maintain status information and a log of all issued certificates and certificate revocation
lists (CRLs). The database is composed of two parts: The server log and the server queue.
Server Log. Stores all certificates and CRLs issued by the server so that administrators can
track, audit, and archive server activity.
Server Queue. Maintains status information (receipt, parsing authorization, signing and
dispatch) as the server processes a certificate request.
Policy Module
All requests received by the server engine are passed to the policy module for validation.
Policy modules are also used to parse any supplemental information provided within a
request and set properties on the certificate accordingly. See the picture page 630.
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Extension Handlers
Extension handlers work in tandem with the policy module to set custom extensions
on a certificate. It can act as a template.
Exit Modules
Exit modules publish completed certificates and CRLs through any number of transports or
protocols. By default, the server notifies each exit module installed on the server whenever
a certificate or CRL is published.
Certificate Services provides a Component Model (COM) interface for writing custom
exit modules for different transports and protocols or for custom delivery options.
Processing Certificate Requests
Certificate Services provides services for processing certificate requests and issuing
digital certificates.
formats it into a PKCS #10 format request and submits it to the server engine.
whether or not the request is authorized, and sets optional certificate properties.
intermediary application of the request status. The
intermediary gets the published
certificate
from the certificate store and passes it back
to the client.
Enrolling Certificates
The process of obtaining a digital certificate is called certificate enrollment.
The process begins with a client submitting a certificate request and ends with the installation
of the issued certificate in the client application.
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CA Certificates (Authorized)
In the process of issuing a digital certificate, the CA validates the identify of the individual
requesting the certificate and then signs the certificate with its own private key.
A client application, such as Microsoft Internet Explorer, checks the CA signature before
accepting a certificate. If the CA signature is not valid or if it comes from an unknown source,
Internet Explorer warns the user by displaying a security message and may prevent the user
from accepting the certificate.
NOTE: If Internet Explorer is set to the low security level, it will not warn the user of invalid
certificates. This setting is appropriate for highly trusted intranet environments and is inappropriate
for Internet access.
A self-assigned CA certificate is also called a root certificate because it is the certificate for the
root CA. The root CA must sign its own CA certificate because by definition there is no higher
certifying authority to sign its CA certificate.
Distribution and Installation of CA Certificates
In contrast, the CA certificate does not require issuance upon demand. Instead, it is created once
and then made readily available to all servers or clients who request certificates from the CA. It is
done one at the Installation.
Installing Certificate Services
You can install Certificate Services by using the Add/Remove Programs utility in Control Panel or
optionally during the installation of Windows 2000 Server.
Certificate Authority Type
**Excellent Quiz question **
The CA type allows selection of how the CA will be utilized in a CA hierarchy and whether or not
the CA will rely upon Active Directory services.
Active directory services.
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require Active Directory services.
the Stand-Alone
CA Information
You must supply information about the initial CA that is created when you install Certificate Services.
Advanced Configuration
The advanced configuration contains options for the type of cryptography algorithms to be used
for the CA that you are creating. The advanced options are the name of the cryptographic provider,
the hash algorithm, the option to use existing public keys and private keys, and the key length.
The snap-in allows you to perform a variety of
administrative tasks:
Certutil.exe is a command-line utility used for administering certificate services. Running certutil
without any command-line switches displays summary information about the local certificate authority.
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If you need to set security fro the CA Web pages, you should use the Internet Information Services
snap-in. Expand the Default Web Site from the console tree and then select CertSrv.
You will need to have NTFS permissions.
Lesson Summary:
or optionally during Windows 2000 Server installation.
Lesson 2:
Public Key Technologies
Windows 2000 extends security by supporting a number of technologies that are based on public
key security, including the Secure Channel authentication package, smart cards, Authenticode, the
Encrypting file System (EFS), and Internet Protocol Security (IPSec).
Secure Channel Authentication Package
In Windows 2000, a Secure Channel (Schannel) authentication package is located below the Security
Support Provider Interface (SSPI), see page 645.
The Schannel authentication package implements the Secure Sockets Layer (SSL) 3.0 protocol and
the Transport Layer Security (TLS) 1.0 protocol.
SSL and TLS are flexible security protocols that can be layered on top of other transport protocols.
The TLS protocol is based on the SSL 3.0 protocol and moves forward as the Internet Engineering
Task Force (IETF) standard. The difference between TLS 1.0 and SSL 3.0 are not significant, but
they are enough that TLS 1.0 and SSL 3.0 cannot interoperate.
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Both the SSL and TLS protocols provide secure data communication through data encryption and
decryption, client authentication, and optional server authentication. Both are typically used to send
and receive private communication across the Internet by using public key cryptography and its
authentication method.
The benefits of SSL and TLS include the following:
server is secure.
Smart Cards
Smart Cards, which are the size of a credit card, can be used to store a user’s public key, private key,
and certificate. Smart cards are a secure way to protect and control a user’s keys, instead of storing
them on a computer.
Security-critical computations are performed by the smart card, instead of exposing a user’s private
key to the computer.
To use a smart card, a computer must have a smart card reader. A smart card is an ISO 7816-
compatible device that contains an embedded microprocessor, an RSA or equivalent cryptography
coprocessor, and local storage. The local storage includes the following:
Smart Card Logon
Windows 2000 introduces PC-based smart card logon as an alternative to passwords for domain
authentication.
During operation, the system recognized a smart card insertion event as an alternative to the standard
Ctrl+Alt+
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The user is then prompted for a smart card PIN code. Much like when you want to take money out
of the bank, maybe our banking cards are infact a type of smart card.
In this system, the smart card also contains a copy of the user’s certificate (issued
by an enterprise CA). This allows the user to roam within the domain.
Authenticode
The growing use of the Internet has led to increased reliance on downloaded active content, such
as Windows-based applications, ActiveX controls, and Java applets. The result has been a
heightened concern for the safety of such downloads, since they often occur as a side effect of
Web scripts without any specific user notification.
Authenticode technology, a security feature in Microsoft’s Internet Explorer, assures accountability
and authenticity for software
components on the Internet. Authenticode verifies that the software
hasn’t been tampered with and identifies the publisher of the software.
Authenticode technology allows software publishers to digitally sign any form of active content,
including multiple-file archives. These signatures may be used to verify both the publishers of the
content and the content integrity at download time.
Encrypting File System
EFS is an extension to the NTFS file system that provides strong data protection and encryption
for files and folders. The encryption technology is based on use of public keys and runs as an
integrated system service, making it easy to manage, difficult to attack and transparent to the user.
The encrypting user’s public key is used in the encryption
process, ensuring data privacy. Decryption
is denied to any user without the corresponding private key. A special key is also generated for each
encrypted file. This key is for emergency use by a qualified administrator in the event that an employee
leaves or a private key is lost.
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Encryption and decryption is done transparently during the I/O process. EFS imposes no discernible
performance penalty during the encryption/decryption process.
EFS also supports encryption and decryption of files stored on remote NTFS volumes. Although
encrypted files can be exported, data is transferred over the network in a clear (unencrypted) format
by default. Windows 2000 provides network protocols such as SSL, TLS, and IPSec to encrypt data
during transfer over the network.
Data Protection
EFS uses a combination of the user’s public and private keys as well as a randomly generated file
encryption key (FEK). The FEK is a 128-bit key for
Data Recovery
The Encrypted Data Recovery Policy (EDRP) is used to specify who can recover data in case a
user’s private key is lost. An EDRP is automatically generated on stand-alone computers to
minimize administration.
Encrypted Backup and Restoration
Because members of the Backup Operators group do not have the keys necessary for decryption,
encrypted data is read and stored in the backup as an opaque stream of data.
Fault Tolerance
Encryption and Decryption are sensitive operations because failure could result in data loss.
Therefore, EFS makes all operations automatic. If an operation cannot be completed, it is
completely undone. For example, if a computer loses power during an encryption operation,
EFS undoes the operation on restart
so that the file is in a consistent state.
You cannot have a
file that is ½ encrypted and not ½ encrypted.
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Once a file is encrypted, the processes of encryption and decryption are automatic and
transparent to users and
applications whenever the file is used. You can perform encryption on
one file at a time or one folder at a time.
You can encrypt a file or folder in Windows Explorer and from the command prompt.
NOTE: It is not possible to use NTFS compression and encryption on the same file.
Compression and encryption are mutually exclusive.
EFS Encryption
EFS encrypts, decrypts, and recovers files. When a user encrypts a file in EFS, the following
process occurs:
scheme.
user’s public key.
recovery agent’s public key. The recovery agent’s public key is obtained from the Encrypted
EFS Decryption **
Users Private Key **
The decryption process uses the DDF, created during encryption, to decrypt a file. When a file is
decrypted in EFS, the following process occurs:
request to the EFS driver.
sends the data to the requesting application.
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EFS Recovery
** Agents Private Key **
Similar to the decryption process. When a file is recovered in EFS, the following process occurs:
file key.
sends the data to the requesting application.
Cipher Command-Line Utility
The cipher command-line utility allows you to encrypt and decrypt files from a command prompt. If no
parameters are used, the cipher command displays the encryption state of the current folder and any
files it contains.
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Parameter Description
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/e Encrypts the specified folders.
/d Decrypts the specified folders.
/s:dir Performs the selected operation on folders in the specified
folder and all subfolders.
/a Performs the selected operation on files with the specified
names.
/I Continues performing the specified operation even after
errors have occurred. By default, cipher stops when an
error is encountered.
/f Forces the encryption or decryption of all specified objects.
/q Reports only the most essential information.
/h Displays files with hidden or system attributes. By default,
these files are not encrypted or decrypted.
/k Creates a new file encryption certificate on the computer
where CIPHER is run.
pathname Specifies a pattern, file or folder.
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IP Security *** CIA ***
IPSec in Windows 2000 is designed to protect sensitive data on a TCP/IP network. IPSec is useful
when the network between two
communicating computers is not secure. It provides confidentiality,
integrity, and authentication of IP traffic for each
packet traversing the network.
When using IPSec, the two computers communicating over the network first agree on the highest
security policy, then each handles the IP Security at its respective end.
Using IPSec to encrypt all IP network traffic ensures that any TCP/IP-based communication is secure
from network eavesdropping. Any routers or switches that are in the path between the communicating
computers can simply forward the encrypted IP packets.
IPSec Policies
With Windows 2000 IPSec, you can create policies that define the type and level of security to be used
during network communication. See Active Directory User and Computers menu, Domain Controllers,
right click on Properties. Group Policies/Edit.
1. Negotiation Policies
The security protocol chosen for negotiation policies is the basis for the security services. For example, if
the IP Authentication Header protocol is chosen, integrity, authentication, and anti-replay services will be
provided but not confidentiality, which means that the encryption is not
performed.
Integrity, which means that yes the data has not changed, Authorization yes it is the authenticated user, and
not confidential, the data will not be encrypted. If you have several policies, you have more levels of the
CIA to worry about.
2. IP Filters
IP filters direct actions based on the destination of an IP packet, what IP protocol is in effect, and the
related ports that the protocol uses. Each IP packet is checked against the IP filter, and if a match is
found, the properties of the associated security policy are used to send the communication.
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3. Security Policies
Security policies are used to configure IPSec attributes. These policies are made up of associated
negotiation policies and IP filters, and are associated with domain controller policies.
A computer logging onto a domain automatically obtains the properties of the default domain and
local policies, including the IPSec policy assigned to the domain policy.
IPSec Components
The Windows 2000 installation process installs the services, protocols, and drivers necessary for IPSec:
IPSec Policy Agent Service
The IPSec Policy Agent service passes the policy information to the IPSec network driver and the
ISAKMP/Oakley protocols. The IPSec Policy Agent service does not store policies locally; instead
it must retrieve them from the Active Directory store.
ISAKMP/Oakley IKE Protocols
Using the information in the IPSec policy, the ISAKMP/Oakley (IKE) protocols negotiate and
establish a Security Association (SA) between computers.
IPSec Driver
This driver examines all IP packets for a match with an IP filter. If a match is found, the IPSec
driver holds the packets in a queue while the ISAKMP/Oakley (IKE) protocols generates the
necessary SA and key to secure the packet.
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IPSec Communication (see diagram page 661)
At the user level, the process of securing the IP packets is transparent and works as follows:
send data to User 2. The security policies assigned to Computer A and Computer B
determine the level of security for the network communication.
associatedwith the assigned security policy to establish the key and a common negotiation
method, or Security
computers to the
Computer B decrypts the data and passes it on to the receiving application.
Lesson Summary:
security, including the Schannel authentication package, smart card, Authenticode, the Encrypting File
and certificate.
multiple-file archives.
files and folders.
when the network between two communicating computers is not secure. It provides confidentiality,
integrity, and authentication of IP traffic per packet.
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Lesson 3:
The Kerberos Protocol in Windows 2000
A standard process within computer security is to include a function that requires users to prove that they
are who they claim to be. This affirmation of identity is accomplished when the user supplies the correct
password for the user account.
Overview of the Kerberos Protocol
The Kerberos protocol is the default authentication provider in Windows 2000 and the primary security
protocol. It allows users to use a single logon to access all resources. The Kerberos protocol verifies
both the identity of the user and the integrity of the session data. This is accomplished by having a
Kerberos service installed on each domain controller and the Kerberos client installed on all computers
running Windows 2000.
NOTE: The Active directory client for Windows 95 and Widows 98 allows users to log on by using the
Kerberos V5 authentication protocol.
When the Kerberos authentication protocol is used, a trusted Kerberos service on a server verifies the
user’s identity. Before connecting to the server the user requests a ticket from the Kerberos service,
called the
The Kerberos service operates as a trusted third-party to generate session keys and grant tickets for
specific client/server sessions.
When the Kerberos service issues a ticket, it contains the
following components:
The expiration period of a ticket is defined by the domain policy. If a ticket expires during an
active session, the Kerberos service notifies the client and the server to refresh the ticket. The
Kerberos service then generates a new session key and the session is resumed.
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Kerberos Protocol Terms
Review the following components of Kerberos:
Principal. A principal, is a uniquely named user, client, or server that participates in a network
communication.
Realm. A realm is an authentication boundary, which can be compared to a Windows 2000 domain.
Each organization wishing to run a Kerberos server established its own realm.
Secret Key. A secret key is an encryption key that is shared by a client or a server and a
trusted third party to encrypt the information that is to be moved between them.
Session Key. The session key is a temporary encryption key used between two principals, with a
lifetime limited to the duration of a single login session.
Authenticator. An authenticator is a record that is used to verify that a request actually originated
from the principal. An authenticator contains information that verifies the identity of the sender and
the time the request was initiated. This information is encrypted with the shared session key that is
known only by the communicating principals.
granting service (TGS). The TGS distributes tickets to clients that wish to connect to services on the network.
Privilege Attribute Certificate. PAC is a structure that contains the user’s security ID (SID).
Tickets. In a basic Kerberos exchange, the client will contact the TGS and request a ticket for the
target server before contacting the target server. A ticket is a record that allows a client to
authenticate itself to a server; it is simply a certificate issued by the Kerberos service. Tickets are
reusable within their life span, which is usually 8 hours.
Ticket Granting Tickets. One Kerberos method is to simply request a ticket for each target server
from the TGS portion of the Kerberos service whenever a user wants to access the specified target
server. This method results in a component of the user’s secret key being exposed on the network
every time a new ticket request is made. A TGT is a request for a ticket and a random session key
to be used with the TGS portion of the Kerberos service.
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Features of the Kerberos Protocol
The kerberos protocol has several advantages over traditional challenge/response authentication
systems.
Mature Open Standard. Kerberos clients on other platforms, such as UNIX, can be authenticated
by Windows 2000.
Faster Connection Authentication. A server running Windows 2000 can verify the client credentials
by using the client-supplied ticket, without having to query the kerberos service.
Mutual Authentication. Of both the client and the server. The Windows NTLM authentication
protocol provides only client authentication, and it assumes that all servers are trusted.
Delegation of Authentication. Delegation of authentication allows a user to connect to an
application server, which in turn can connect to one or more additional servers on the client’s behalf,
by using the client’s credentials.
Transitive Trust. Authentication credentials issued by one Kerberos service are accepted by all
Kerberos services within the domain.
Kerberos Authentication Process
The Kerberos authentication process involves the client computer negotiating exchanges between
the target server and the KDC. It works as follows:
The client sends an initial AS request to the AS portion of the Kerberos service, were the principal
name is included. The Kerberos service generates an AS reply and sends it to the client.
secret key.
is encrypted with the client’s secret key.
The client generates and sends a TGS request that contains the client’s and target server’s
principal names etc.
The TGS portion of the Kerberos service generates and sends a TGS reply to the client.
The client extracts the session key for the target server and generates a request for the server.
The target server decrypts the ticket by using its secret key to obtain the session key. The
server then uses the session key to decrypt the authenticator to verity the client.
NOTE: The AS and TGS exchanges with the Kerberos service operate over User Datagram
Protocol (UDP) port 88. The exchanges between the client and target server are dependent
on the protocol in use between the two principals.
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Kerberos Delegation
Occasionally, it is necessary for an application server to connect to another server on behalf
of a client.
The Kerberos authentication protocol supports delegated authentication. This type of
authentication is used when a client transaction involves multiple servers. There is no
restriction on the number of consecutive servers that can delegate authentication.
The following steps
describe the access of resources involving two servers:
The client requests and receives a ticket for target Server A from the Kerberos service.
The client sends the ticket directly to Server A.
Server A sends a request, impersonating the client, to the Kerberos service for a ticket for target
Server B. The Kerberos service responds with a ticket that allows the client to access Server B.
Server A can then send the ticket to Server B, Accessing Server B as the client. See page 670.
Kerberos Logon Processes
The addition of Kerberos as an authentication package in Windows 2000 affects various aspects
of the logon process.
Local Interactive Logon
When a local interactive logon occurs, the user logs on with a user account that exists on the local
computer rather than with a domain user account. For local user accounts, the following occurs in
Windows 2000:
it forwards the request to the Local Security Authority (LSA).
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when authenticating logon request for domain user accounts, not local user accounts.
Domain Interactive Logon
The exchange that occurs when a user logs on to Windows 2000 with a domain user account is
similar to the basic Kerberos exchange.
Kerberos secret key)and a session key for the TGS exchanges (encrypted with the
client’s secret key).
and realm, the TGT to identify the client, and the local workstation name as the target server.
Windows 2000 services use the Kernel Mode Security Support Provider Interface (SSPI)
to perform authentication.
The Network communication occurs in two segments: Protocol negotiation and session setup.
Before a user can establish a session with the server, the client computer and the server must agree
on the security protocol to use by determining which version of security they both support.
Kerberos Public Key Support
Windows 2000 includes extensions to the Kerberos V5 authentication protocol to support public
key, based authentication. The kerberos service verifies such a request by using the user’s public
key that is obtained from the user’s X.509 certificate published to the Active Directory store.
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Lesson Summary:
the target server and the KDC.
similar to the basic Kerberos exchange.
key-base authentication.
Lesson 4:
Security Configuration Tools
Windows 2000 provides a set of security configuration tools that are designed to reduce the costs
associated with security configuration and analysis of Windows 2000 networks. The security
configuration tools include three snap-ins: the Security Configuration And Analysis snap-in, the
Security Templates, snap-in, and the Group Policy snap-in.
Security Configuration and Analysis Snap-in
This allows you to configure and analyze local system security.
Security Configuration. You can import security. Templates created with the Security Templates
snap-in, and apply these templates to the group policy object (GPO) for the local computer. This
immediately configures the system security with the levels specified in the template.
Security Analysis. The state of the operating system and applications on a computer is dynamic.
For example, security levels may be required to change temporarily to enable immediate resolution
of an administrative or network issue. Regular analysis enables an administrator to track and ensure
an adequate level of security on each computer as part of an enterprise risk management program.
Using the Security Configuration and Analysis Snap-in
This Security Configuration and Analysis snap-in reviews and analyzes your system security setting
and recommends modifications to the current system settings. Administrators can use the snap-in to
adjust the security policy and detect security flaws that arise in the system. The security configuration
and Analysis snap-in allows you to perform a variety of tasks:
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Security Templates Snap-in
A security template is a physical representation of a security configuration; it is a file where a group
of security settings may be stored. Windows 2000 includes a set of security templates, each based
on the role of a computer.
You can assign Templates snap-in can be used to create templates for one or more computers.
A security template is a physical file representation of a security configuration, and can be applied
to a local computer or imported to a Group Policy Object GPO in the Active Directory service.
When you import a security template to a GPO, Group Policy processes the template and makes
the corresponding changes to the members of that GPO, which may be users or computers.
The security templates snap-in allows you to perform a variety of tasks:
Group Policy Snap-in
Security settings define the security-relevant behavior of the system.
When determining settings for a GPO that contains multiple computers, the organizational and functional
character of that given site, domain, or organizational unit (OU) must be considered.
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The Group Policy snap-in allows you to configure security centrally in the Active Directory Store. A
security Setting folder is located on the Computer configuration node and the User Configuration node.
Lesson Summary:
Windows 2000 security settings and perform periodic analyses of the system to ensure that the
configuration remains intact or to make necessary changes over time.
more computers.
Lesson 5:
Microsoft Windows 2000 Auditing
Auditing is a tool for tracking user activities and system-wide events.
Overview of Windows 2000 Auditing
Auditing in Microsoft Windows 2000 is the process of tracking both user activities and Windows
2000 activities, called events, on a computer. An audit entry in the security log contains the
following information:
Using an Audit Policy
An audit policy defines the types of security events that Windows 2000 records in the security
log on each computer.
Windows 2000 writes events to the security log on the computer where the event occurs. If
a user tries to log on and cannot, the security log will have an entry, but it will list the Domain
Controller who tried the authentication process. You can set up an audit policy for a computer
to do the following:
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particular user to read a specific file, changes to a user account or to group memberships, and
changes to your security settings.
Planning an Audit Policy
When you plan an audit policy, you must determine the computers on which to set up auditing.
Auditing by default is turned off.
The types of events that you can audit include the following:
Auditing Requirements
You must have the Manage and Security Log permission for the computer where you want to
configure an audit policy or review an audit log. Windows 2000 grants these rights to the Administrators
group by default.
The files and folders to be audited must be on NTFS volume
Setting up Auditing
It is a two-part process:
auditing of specific objects.
printers and Active Directory objects. Windows 2000 then tracks and logs the specified events.
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Auditing Access to Active Directory Objects
To audit Active Directory object access, you must configure an audit policy and then set auditing for
specific objects, such as users, computers, organization units (OUs), or groups by specifying which
types of access and access by which users to audit.
Go into Active Directory objects, enable the Audit Directory Service Access policy in the Group
Policy snap-in.
Windows 2000 Logs
Application Log. Errors, warnings, or information that programs such as a database program or an
e-mail generate.
Security Log. Success or failures of audited events.
System Log. Errors, warnings and information that Windows 2000 generates.
Lesson Summary:
a computer.
within log files.