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Lecture 6. Information protection infrastructure at the application and presentation layers

Plan:

1

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📌 What is the OSI Model?�

  • The OSI Model (Open Systems Interconnection Model) is a 7-layer framework that explains how data travels from one computer to another over a network.
  • It is not a real protocol — it is a conceptual model used for understanding and designing networks.

Layer 7 – Application

  • Closest to the user
  • Provides network services to applications
  • Examples: HTTP, FTP, SMTP, DNS

👉 This is where users interact with the network.

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  • Layer 6 – Presentation
  • Responsible for:
    • Data formatting
    • Encryption / Decryption
    • Compression
  • 👉 Makes sure data is readable for the application.
  • Layer 5 – Session
  • Manages sessions (connections) between devices
  • Opens, maintains, and closes communication
  • 🔹 Layer 4 – Transport
  • Ensures reliable or fast delivery
  • Protocols:
    • TCP (reliable)
    • UDP (fast, less reliable)
  • 🔹 Layer 3 – Network
  • Logical addressing
  • Routing
  • IP protocol works here
  • 🔹 Layer 2 – Data Link
  • MAC addressing
  • Switches work here
  • 🔹 Layer 1 – Physical
  • Cables, signals, voltages
  • Hardware transmission

How Data Moves (Encapsulation Idea)

  • When sending data:
  • Application → Presentation → Session → Transport → Network → Data Link → Physical
  • Each layer adds its own header information.
  • When receiving data, the process happens in reverse.

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What is the TCP/IP Model?�

  • The TCP/IP model is a layered networking framework that explains how data is communicated between devices over a network using standardized protocols to ensure reliable and efficient transmission.
  • Defined as a four-layer architecture consisting of Application, Transport, Internet, and Network Access layers.
  • Standardized by RFC 1122, which specifies its structure and behavior.
  • Simpler and more practical than the seven-layer OSI model.
  • Serves as the core framework of the modern Internet and networking systems.

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Layers of TCP/IP Model�

  • 1. Application Layer
  • The top layer of the TCP/IP model, closest to the user, where applications like web browsers, email clients, and file-sharing tools interact with the network. It provides an interface between user software and the lower layers that handle data transmission, enabling seamless communication over the network.
  • Acts as a bridge between user applications and lower network layers
  • Supports protocols such as HTTP, FTP, SMTP, and DNS
  • Handles data formatting so information is correctly understood by both sender and receiver
  • Provides encryption for secure communication
  • Manages sessions to track ongoing connections

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2. Transport Layer�

  • Ensures reliable and efficient delivery of data between devices, managing segmentation, ordering, and retransmission as needed.
  • Segmentation and Reassembly: Breaks large messages into packets and reassembles them at the destination.
  • Reliable Delivery & Error Handling: TCP checks for errors, resends lost data, and ensures correct order.
  • Fast Communication: UDP provides low-latency, connectionless delivery without error checking.
  • Flow Control: Prevents the receiver from being overwhelmed by regulating data flow.
  • Multiplexing: Uses port numbers to allow multiple applications to share the network simultaneously.

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3. Internet Layer�

  • Responsible for addressing, packaging, and routing data packets so they can travel across networks and reach the correct destination device. It ensures that data can move between different networks efficiently.
  • Logical Addressing: Assigns IP addresses to identify source and destination devices.
  • Packet Routing: Determines the best path for data to travel across networks.
  • Fragmentation and Reassembly: Breaks large packets into smaller ones for transmission and reassembles them at the destination.
  • Protocol Support: Primarily uses IP (Internet Protocol), along with supporting protocols like ICMP for error reporting and ARP for address resolution.

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4. Network Access (Link Layer)�

  • Responsible for physically transmitting data over network hardware, including cables, switches, and wireless connections. It handles how data is formatted for the network medium and ensures it reaches the next device on the path.
  • Physical Transmission: Sends and receives raw bits over physical media like Ethernet cables, fiber optics, or Wi-Fi.
  • Framing: Organizes data into frames for proper transmission and recognition by devices.
  • Error Detection: Detects transmission errors using checksums or CRC.
  • MAC Addressing: Uses hardware addresses to identify devices within the same network segment.
  • Access Control: Determines how multiple devices share the same physical medium, avoiding collisions.

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Working of TCP/IP Model�

  • The working of TCP/IP can be explained with the help of the diagram given below and explained:

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Security issues in application layer protocols

1. Using HTTP instead of HTTPS

🔴 Issue: If the app uses HTTP, the data is unencrypted and attackers could intercept it on the network.

2. DNS spoofing

🔴 Issue: If DNS is vulnerable, an attacker can alter the requested domain and redirect the user to a fraudulent website.

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4. FTP vulnerability

🔴 Issue: FTP operates without encryption, which allows attackers to disrupt or modify the file transfer process. 5. Lack or weakness of API authentication

🔴 Issue: If the API works without authentication or with weak tokens, attackers can access it without permission.

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What is identification?

Identification – is the process of determining the user who is entering the system. The user shows their identity through a login, email or another identifier.

🔹 Identification only determines who you are, but does not verify it (verification – is performed through authentication).🔹 For example, the user enters a login, but the system uses a password or other protective mechanisms to verify it.

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Authenticating Users

Authentication – the process of a user proving their identity. It is implemented using the following methods:

  1. Single-factor authentication

✅ The user accesses the system with only one factor. ✅ For example: Accessing the system with only login and password. ❌ Less secure, because the password can be stolen or compromised.

2) Two-factor authentication

✅ The user is verified using two factors:1️⃣ Something you know (e.g., password) 2️⃣ Something you have

For example:

  • After entering the login and password, a code is sent via SMS or a mobile app.
  • This code must also be entered to log in.
  • Most banks and email services (Gmail, Facebook, Telegram) use this method.

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Multi-factor authentication

Higher protection than two-factor authentication. ✅ At least three different verification methods are used:�1️⃣ Password or PIN code�2️⃣ Code via SMS or mobile app�3️⃣ Fingerprint, facial recognition (Face ID) or USB-token (YubiKey)

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User Management

User management – this is the process of organizing all users in the system, their roles and permissions.

1) User roles and permissions

🔹 Admin (Administrator) – Manages the system, has all permissions.🔹 User – Only has access to their own data.🔹 Moderator – Has the right to edit and manage certain data.🔹 Guest (Mehmon) – Has limited permissions only (e.g., view the site only).

RBAC (Role-Based Access Control) – A role-based management system where each user is granted only the necessary permissions.

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3. Organizing protected remote users

Core central requirements for remote operations

The remote system must have a secure connection and the data must be protected. The following requirements are necessary:

✅Complex authentication passwords�✅ Send over encrypted channels�✅ Maintain network security �✅ Restrict user rights �✅ View endpoint access capacity

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Technologies for sharing remote issues

1) VPN (Virtual Private Network) – disable

VPN – a technology that provides encrypted and protected connections for remote users over a network.

🔹 Why is a VPN needed?

  • Provides users with tools to access the internet.
  • Encrypted communication, i.e., data is protected from MITM (Man‑in‑the‑Middle) attacks.
  • It hides IP addresses and prevents unauthorized users from accessing systems.

🔹VPN types:�✅ Site-to-Site VPN – Provides access for enterprises.�Remote Access VPN – Provides access for remote users.✅ S VPN – Grants SL VPN access via a browser.�✅

🔹 Popular VPN technologies:

  • OpenVPN – Open‑source with strong encryption algorithms.
  • Cisco – For large organizations.

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Zero Trust Security Model – Concept of Untrusted Connection

Zero Trust – a model where users are given no trust no trust is granted and every authentication request is always enforced.

🔹 Zero Trust Use Cases:"Never trust, always verify – Even a user within the organization also undergoes continuous verification.✅ Authenticate each sessionMinimal permission – only has access rights to the necessary data access rights.✅ Effective authentication using TIV and context

🔹 Zero Trust operation mechanism:1️⃣ To securely access the system via multi-factor authentication proceeds. 2️⃣ Each request is checked by the E monitoring system is verified. 3️⃣ Data access depends on context (which device, which location, which time). 4️⃣ Continuous monitoring

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Security firewall (Firewall) and IDS/IPS

Because it is connected via a remote network, it is very important for the network.

🔹 What is a Firewall?

  • A hardware device that protects the "organization" from attacks or a hardware device.
  • Controls inbound (incoming) and outbound (outgoing) traffic.
  • DDoS, port scanning, brute-force attacks.

🔹 What is IDS/IPS?IDS (Intrusion Detection System) – Detects suspicious activity on the network and notifies the administrator. ✅ IPS (Intrusion Prevention System) – Blocks suspicious alerts and mitigates them.

Popular firewall and IDS/IPS systems:

  • Cisco ASA, Palo Alto Networks, Fortinet FortiGate – Firewall hardware for large enterprises.
  • Snort, Suricata – IDS/IPS systems.

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Restricting Users' Rights (RBAC)

Remote users should be given only the necessary rights.

🔹 RBAC (Role-Based Access Control) – grant permissions to users based on their roles. �🔹 Least Privilege Access – users should only be able to access the necessary resources.

Benefits of RBAC:

  • Administrator – Has the right to manage all devices.
  • Employees – Can only access their own permissions.
  • Remote assistance – Restricted permissions only after being specified.

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Application layer – Communication between humans and data transmission

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General risks

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Inherited vulnerabilities Secure Lower Layer Protocols; Application Encryption; Nonstandard Application

Authentication issues

Application layer protocols

Most parts of any type

does not support authentication

Both HTTP and, SMTP

also unauthenticated

Customers unauthenticated

allows connection to servers.

Direct connection to the system

Application layer protocols

operational

directly in the system

with applications

works correctly. Most

applications disks, files and

to execution

exists and also on this network

Command permissions are available.

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SMTP protocol

  • Example of an SMTP session given with MUA information (highlighted in bold).
  • % telnet rudolf 25 Trying...
  • Connected to rudolf.npole.org. Escape character is '^]'.
  • 220 rudolf.npole.org ESMTP Sendmail 8.8.6 (PHNE_17135)/8.7.3 SMKit7.1.1 hp hp; Thu, 25 Apr 2002 09:17:17 -0600 (MDT) helo ranch.npole.org
  • 250 rudolf.npole.org Hello ranch.npole.org [10.2.241.27], pleased to meet you mail from: santa@npole.org
  • 250 santa@npole.org... Sender ok rcpt to: grinch@xmas.mil
  • 250 grinch@xmas.mil... Recipient ok data
  • 354 Enter mail, end with "." on a line by itself
  • Subject: Ho ho ho
  • I know you've been a bad boy.
  • 250 JAA19237 Message accepted for delivery quit

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SMTP was developed not for the purpose of ensuring security, but to guarantee that messages are delivered reliably and in a timely manner. When the protocol was initially created, reliability was considered a more important issue than security. This viewpoint has led to a number of security risks that are not dependent on the implementation of MUA and MTA.

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SMTP protocol risks fake subject and spam

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Fake email message

Fake email message is very

issues

may cause

can cause danger..

This

as

example organization

One can cite a manager's message about dismissing an organization employee from their position.

SPAM

Unwanted mail message (spam)

fake electronic messages

malicious purposes

for use example can be

can be. At first glance a message

legal entity by

appears as sent also,

actually completely another person

by sent will be.

MAIL logs

Electronic when forging electronic mail, servers listed in false headers are not saved in logs, the systems that sent the fake message

but it may store information about accounts for the real recipient.

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Fake titled spam message

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HTTP protocol

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HTTP was developed as a flexible protocol for transmitting data in real time.

The initial specification of HTTP 1.0 was defined in RFC1945. Usually HTTP is used for transmitting HTML

although it is used (XML-based content and formatting specification), the protocol is not dependent on the content being transmitted. HTTP can easily transmit text or binary files, documents, or images.

GET / HTTP/1.0

Host: www.hackerfactor.com

HTTP/1.1 200 OK

Date: Sat, 21 Jan 2006 16:49:12 GMT Server: Apache/1.3.34

(Unix) mod_pointer/0.8 PHP/4.4.1

X-Powered-By: PHP/4.4.1 Connection: close Content-Type: text/html

<html>

<head><title>Hacker Factor Solutions</title></head> ...

</html>

www.hackerfactor.com site HTTP request (in black font) and its response

HTTP response status code classification

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URL EXPLOITATION (Use/Exploitation)

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Hostname modification attack

1

3

5

4

2

Query misuse

(Query Abuse)

Cross-Site Scripting

Host and URL

masking

SQL Injections

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Main risks of HTTP

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Unauthenticated client and server

1

3

5

4

2

Server address identification (Server Location Profiling)

Insecure applications (Insecure Applications)

Information loss (Information leakage)

Unauthorized access to the operating system

Unauthenticated client and server

HTTP on the server does not provide many options for authenticating the HTTP client. Although authentication is commonly used, it does not ensure the confidentiality of user personal data transmitted over the network. Because the data is transmitted in clear text, simple plain‑text data transmission makes authentication as vulnerable as in telnet and FTP. While SSH can be used instead of telnet and FTP, the slower connection speed of SSH does not allow it to replace HTTP.

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Presentation layer

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To provide communication between network‑connected computers, application data must be converted into a language understandable by machines.

The presentation layer of the OSI model defines the functional capabilities of these conversions.

taqdimot sathi ushbu

o‘zgartirishlarning funksional imkoniyatlarini aniqlab beradi..

Presentation layer

Presentation layer

This layer manages syntax agreement and data transformation.

In addition, the presentation layer also controls the session layer by creating and terminating session requests.

seans sathini ham boshqaradi.

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Presentation layer

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Encoding

Fake email message very

to

expose

can bring danger..

To

this

as

example

An example could be a manager’s message about dismissing an organization employee from their position.

Phishing

Unwanted email message

Fake electronic

for malicious purposes

can serve as an

It may appear

but in reality

Encryption

In email spoofing, servers mentioned in false headers are not stored in logs; the systems that sent the fake message

may keep information about accounts for the real recipient.

Elektron pochtani qalbakilashtirishda yolg‘on sarlavhalarda keltirilgan serverlar jurnallarda saqlanmaydi, qalbaki xabarni yuborgan tizimlar

esa haqiqiy qabul qiluvchi uchun akkauntlar haqida malumotni o‘zida saqlashi mumkin.

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Thank you for your attention