Bài giảng Web technologies and e-Services - Bài 12: Web Security - Trường Đại học Bách khoa Hà Nội
IT4409: Web Technologies
and e-Services
Web Security
1
Outline
1. What is web security?
2. HTTPS
3. Session Management
4. Authentication
5. Common Web Attacks
2
What is web security?
v Website security is the act/practice of protecting
websites from unauthorized access, use,
v Effective website security requires design effort
across the whole of the website:
§ Web application
§ Configuration of the web server
§ Policies for creating and renewing passwords
§ Client-side code.
3
Facts and Stats
v 95% of breached records came from only three
industries in 2016
v There is a hacker attack every 39 seconds
v 43% of cyber attacks target small business
v The average cost of a data breach in 2020 will
exceed $150 million
v In 2018 hackers stole half a billion personal
records
v Over 75% of healthcare industry has been infected
with malware over 2018
v Large-scale DDoS attacks increase in size by 500%
4
Facts and Stats
v Approximately $6 trillion is expected to be spent
globally on cybersecurity by 2021
v By 2020 there will be roughly 200 billion connected
devices
v Unfilled cybersecurity jobs worldwide will reach 3.5
million by 2021
v 95% of cybersecurity breaches are due to human error
v More than 77% of organizations do not have a Cyber
Security Incident Response plan
v Most companies take nearly 6 months to detect a data
breach, even major ones
v Share prices fall 7.27% on average after a breach
v Total cost for cybercrime committed globally has
added up to over $1 trillion dollars in 2018
5
Outline
1. What is web security?
2. HTTPS
3. Session Management
4. Authentication
5. Common Web Attacks
6
HTTPS
v Hypertext transfer protocol secure (HTTPS) is the
secure version of HTTP, which is the primary
protocol used to send data between a web browser
and a website.
• HTTPS is encrypted in order to
increase security of data
transfer.
• This is particularly important
when users transmit sensitive
data, such as by logging into a
bank account, email service, or
health insurance provider.
7
HTTPS
v HTTPS uses an encryption protocol to encrypt
communications.
v The protocol is called Transport Layer Security (TLS),
although formerly it was known as Secure Sockets
Layer (SSL).
§ The private key - this key is controlled by the owner of a website
and it’s kept, as the reader may have speculated, private. This key
lives on a web server and is used to decrypt information
encrypted by the public key.
§ The public key - this key is available to everyone who wants to
interact with the server in a way that’s secure. Information that’s
encrypted by the public key can only be decrypted by the private
key.
8
Outline
1. What is web security?
2. HTTPS
3. Session Management
4. Authentication
5. Common Web Attacks
9
Session Management
v A web session is a sequence of network HTTP
request and response transactions associated to
the same user.
v Modern and complex web applications require the
retaining of information or status about each user
for the duration of multiple requests.
v Therefore, sessions provide the ability to establish
variables – such as access rights and localization
settings – which will apply to each and every
interaction a user has with the web application for
the duration of the session.
10
Session Management
v Web applications can create sessions to keep track
of anonymous users after the very first user
request.
11
Session Management
v The disclosure, capture, prediction, brute force, or
fixation of the session ID will lead to session
hijacking (or sidejacking) attacks.
v An attacker is able to fully impersonate a victim
user in the web application.
v Attackers can perform two types of session
hijacking attacks, targeted or generic.
12
Outline
1. What is web security?
2. HTTPS
3. Session Management
4. Authentication
5. Common Web Attacks
13
Major security issues
v Prevent unauthorized users from accessing
sensitive data
§ Authentication: identifying users to determine if they are
one of the authorized ones
§ Access control: identifying which resources need protection
and who should have access to them
v Prevent attackers from stealing data from network
during transmission
§ Encryption (usually by Secure Sockets Layer)
14
Authentication
v Collect user ID information from end users (“logging
in”)
§ usually by means of browser dialog / interface
§ user ID information normally refers to username and password
v Transport collected user ID information to the web
server
§ unsecurely (HTTP) or securely (HTTPS = HTTP over SSL)
v Verify ID and passwd with backend Realm (“security
database”)
§ Realm maintains username, password, roles, etc., and can be
organized by means of LDAP (Lightweight Directory Access
Protocol), RDBMS, Flat-file, etc.
§ Validation: the web server checks if the collected user ID &
passwd match with these in the realms.
v Keep track of previously authenticated users for
further HTTP operations
15
WWW-Authenticate
v The authentication request received by the browser will
look something like:
§ WWW-Authenticate = Basic realm=“defaultRealm”
• Basic indicates the HTTP Basic authentication is requested
• realm indicates the context of the login
• realms hold all of the parts of security puzzle
• Users
• Groups
• ACLs (Access Control Lists)
v Basic Authentication
§ userid and password are sent base 64 encoded (might as well be
plain text)
§ hacker doesn’t even need to unencode all he has to do is “replay”
the blob of information he stole over and over ( this is called a
“replay attack”)
16
WWW-Authenticate
v Digest Authentication
§ attempts to overcome the shortcomings of Basic Authentication
§ WWW-Authenticate = Digest realm=“defaultRealm”
nonce=“Server SpecificString”
§ see RFC 2069 for description of nonce, each nonce is different
§ the nonce is used in the browser in a 1-way function (MD5, SHA-
1….) to encode the userid and password for the server, this
function essentially makes the password good for only one time
v Common browsers don’t use Digest Authentication but an
applet could as an applet has access to all of the Java
Encryption classes needed to create the creation of a
Digest.
17
Outline
1. What is web security?
2. HTTPS
3. Session Management
4. Authentication
5. Common Web Attacks
18
Common Web Attacks
Client side
Server side
• SQLi
v XSS
v CSRF
• Brute-force
• File upload
• Command injection
19
Cross-Site Scripting - XSS
v Cross-site scripting (XSS) is a security exploit which
allows an attacker to inject into a website malicious
client-side code.
v This code is executed by the victims and lets the
attackers bypass access controls and impersonate users.
20
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27/04/2022
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