Financial crime, Motivations and Typologies (CY-803 (B)) - Unit 2 Short Notes

UNIT 2: MOBILE & WIRELESS TECHNOLOGIES & SECURITY

Based on Past Examination Papers (May 2024)

I. FOUNDATIONAL WIRELESS NETWORK CONCEPTS & ARCHITECTURES

A. Wireless Personal Area Network (WPAN)

A WPAN is a short-range wireless network (typically < 10 meters) designed for interconnection of personal devices (e.g., smartphones, laptops, headsets, wearables).

Distinguishing Characteristics vs. Other Wireless Networks:

[!TIP] Exam Focus: WPAN is defined by personal scope, low power, and short range. Contrast clearly with WLAN's "local" building/campus coverage.

B. Wireless Local Area Network (WLAN)

A WLAN is a wireless network that connects devices within a limited area (home, office, campus) using radio waves, providing access to a wired LAN and the internet.

• Core Principle: Uses an Access Point (AP) as a central hub. Client devices (stations) communicate with the AP, which bridges traffic to the wired network.

• Components: Wireless clients (laptops, phones), Access Points (APs), Distribution System (wired backbone).

• Common Use Cases: Office internet, public hotspots, home networking, campus connectivity.

• Standards: Governed by IEEE 802.11 family (Wi-Fi).

C. Mesh Networks & Multi-hop Relay

• Multi-hop Relay: In a wireless network, a packet travels from source to destination via one or more intermediate relay nodes (other mesh nodes), instead of a single direct transmission.

• Significance in Mesh Networks:

  1. Extended Coverage: Nodes can relay data for others, expanding network reach without additional infrastructure.

  2. Robustness & Reliability: If one node fails, traffic can dynamically reroute through alternate paths (self-healing).

  3. Load Balancing: Traffic can be distributed across multiple paths, reducing congestion.

  4. Connectivity in Obstacles: Useful in environments with obstacles where direct line-of-sight (LoS) is not always possible.

D. Ad Hoc Networks

An Ad Hoc Network (or MANET) is an infrastructure-less, decentralized wireless network where nodes communicate directly with each other and act as both clients and routers.

Classification of Routing Protocols:

[!TIP] Exam Focus: Be able to define and contrast the three types. Remember: Proactive = always updated tables (high overhead), Reactive = find when needed (high latency), Hybrid = mix of both.

II. MOBILE NETWORK GENERATIONS & TECHNOLOGIES

A. Evolution & Comparison: 3G vs. 4G

Key Technological & Performance Differences:

B. General Packet Radio Service (GPRS)

• Definition: A 2.5G (enhancement to 2G GSM) packet-switched data service.

• Key Features & Capabilities:

  1. "Always-On" Connection: No need to establish a circuit for each session (unlike circuit-switched data).

  2. Packet-Switched Domain: Shares radio channels efficiently among users based on demand.

  3. Higher Data Rates: Theoretical up to ~114 Kbps (typically 40-50 Kbps).

  4. New Network Elements: Introduces SGSN (Serving GPRS Support Node) and GGSN (Gateway GPRS Support Node) to the GSM core.

• Role: Enabled mobile internet, email, and basic web browsing on early mobile phones, paving the way for 3G.

C. Universal Mobile Telecommunication System (UMTS)

• Overview: The primary 3G standard developed by 3GPP, evolving from GSM.

• Key Architectural Components & Objectives:

  • UTRAN (UMTS Terrestrial Radio Access Network): Replaces BSS. Consists of Node B (base station) and RNC (Radio Network Controller).

  • Core Network (CN): Evolves from GSM MAP. Includes Circuit-Switched (MSC, VLR) and Packet-Switched domains (SGSN, GGSN).

  • Objective: Provide global mobile broadband with support for seamless roaming, higher data rates (384 Kbps - 2 Mbps), and enhanced multimedia services (video calls).

D. Long-Term Evolution (LTE)

• Definition: A 4G precursor/standard (often marketed as 4G) defined by 3GPP. Focuses on high-speed packet-switched data.

• Key Features & Benefits:

  1. OFDMA (Downlink): Provides high spectral efficiency and resistance to multipath fading.

  2. MIMO (Multiple Input Multiple Output): Uses multiple antennas at Tx/Rx to increase throughput and link reliability.

  3. Flat IP Architecture: Simplified, all-IP core network (EPC) reduces latency and complexity.

  4. High Throughput & Low Latency: Targets 100 Mbps+ downlink, < 50 ms latency.

  5. Flexible Spectrum: Can operate in various bandwidths (1.4 to 20 MHz).

E. WiMAX (Worldwide Interoperability for Microwave Access)

• Physical Layer Details:

  • Modulation: Primarily uses OFDM (Orthogonal Frequency Division Multiplexing) for both downlink and uplink. This combats multipath delay spread.

  • Multiple Access: OFDMA (Orthogonal FDMA) for downlink; SC-FDMA (Single-Carrier FDMA) for uplink (to reduce peak-to-average power ratio).

• Operated Frequency Bands:

  • Licensed Bands: 2.3 GHz, 2.5 GHz, 3.5 GHz (common for mobile WiMAX).

  • Unlicensed Bands: 5.8 GHz (for fixed WiMAX, similar to Wi-Fi).

III. WIRELESS COMMUNICATION PROTOCOLS & STANDARDS

A. Wi-Fi Standards Evolution (IEEE 802.11)

Chronological Development & Implications:

*With 4 spatial streams.

Trend: Shift from 2.4 GHz-only to dual-band (2.4/5/6 GHz), MIMO adoption, increasing spectral efficiency, and optimization for high-density scenarios.

B. IP Mobility Management: Mobile IPv4 vs. Mobile IPv6

Core Differences:

[!TIP] Exam Focus: Key contrast: MIPv4 relies on triangle routing & tunneling; MIPv6 supports route optimization & uses routing headers.

C. TCP over Wireless Networks

Challenges of Standard TCP in Wireless Environments:

1. High Bit Error Rate (BER): Wireless links are noisy. Packet loss is often due to corruption, not congestion. Standard TCP interprets all loss as congestion and reduces window size unnecessarily (congestion collapse).

2. Large Round-Trip Time (RTT) & Variability: Satellite links, handoffs cause RTT spikes and jitter, affecting TCP's RTT estimation and retransmission timeout (RTO).

3. Frequent Handoffs: During mobile handoff, connection can break, causing long timeouts and severe throughput drop.

4. Asymmetric Links: Uplink often has lower bandwidth/higher loss than downlink, affecting ACK flow.

General Adaptation Concepts: Solutions involve splitting the connection (e.g., at the base station), local retransmission (to hide wireless loss from TCP), explicit congestion notification (ECN), or TCP variants tuned for wireless (e.g., TCP Westwood, TCP Veno).

D. IPv4 vs. IPv6 Packet Structure

Purpose of Encapsulation Header: To carry control information (source/dest addresses, protocol type, etc.) for routing and delivery across networks.

Comparative Analysis of Header Structure:

Key Takeaway: IPv6 header is fixed-length, simpler, and removes rarely used fields (like header checksum) to improve router performance, while adding extension headers for future scalability.

IV. ENABLING TECHNOLOGIES & APPLICATIONS

A. Radio Frequency Identification (RFID)

• Definition: A technology that uses electromagnetic fields to automatically identify and track tags attached to objects.

• System Components:

  • RFID Tag: Contains a microchip (for data) and an antenna. Can be passive (no battery, powered by reader's signal), active (has battery), or semi-passive.

  • RFID Reader/Interrogator: Emits radio waves and receives signals from tags.

  • Antenna: On reader and tag for signal transmission/reception.

  • Middleware/Software: Processes data, filters, and sends to backend systems.

• Principle of Operation (Passive Tag):

  1. Energy Transfer: Reader emits RF signal. Passive tag's antenna captures this energy, powering the chip.

  2. Backscatter Communication: Tag modulates the incident signal (changes its reflection properties) to send its stored data (ID) back to the reader. This is backscatter.

• Data Transmission Mechanism: Load Modulation. The tag chip changes the electrical load on its antenna, which in turn changes the amplitude/phase of the reflected signal that the reader detects and decodes.

B. E-Commerce

• Definition: The buying and selling of goods or services, and the transmission of funds or data, over an electronic network, primarily the internet.

• Transformation of Traditional Business Models:

  • B2B (Business-to-Business): Streamlined supply chains, electronic catalogs, automated procurement (e.g., Alibaba).

  • B2C (Business-to-Consumer): Direct online retail (e.g., Amazon), 24/7 availability, global reach, personalized marketing.

  • C2C (Consumer-to-Consumer): Enabled by platforms (eBay, Facebook Marketplace), facilitating peer-to-peer sales.

  • C2B (Consumer-to-Business): Consumers offer products/services to businesses (e.g., freelance platforms).

  • Key Enablers: Secure payment gateways, logistics/supply chain integration, web/mobile platforms, digital marketing, trust/review systems.

C. Electronic Payment Systems

• Definition: Systems that facilitate financial transactions electronically between buyers and sellers without traditional paper instruments (cash, checks).

• Categories & Mechanisms:

  1. Card-Based: Credit/Debit cards via Payment Gateways (e.g., Stripe, PayPal). Uses PAN, encryption (SSL/TLS), and often 3-D Secure for authentication.

  2. Digital Wallets/E-Wallets: Store payment info (card details, bank accounts) in a secure app (e.g., Apple Pay, Google Pay, Paytm). Often use tokenization and NFC for contactless payments.

  3. Bank Transfers/Online Banking: Direct transfer from bank account (e.g., NEFT, IMPS, wire transfer). Requires secure online banking login.

  4. Cryptocurrencies: Decentralized digital currencies (e.g., Bitcoin) using blockchain for peer-to-peer transactions.

• Facilitation Mechanism: They provide secure channels (encryption, SSL/TLS), authentication (passwords, OTP, biometrics), authorization (issuer approval), and settlement infrastructure between financial institutions.

V. SECURITY CONSIDERATIONS & MODELS

A. Denial of Service (DoS) / Distributed Denial of Service (DDoS)

• Definition: An attack where the objective is to disrupt the availability of a machine or network resource for its intended users.

• DoS: Single-source attack flooding a target.

• DDoS: Multiple compromised systems (a botnet) attack a single target, making it harder to block.

• General Attack Vectors in Networked/Wireless Contexts:

  1. Flooding: Overwhelming target with excessive requests (HTTP flood, ICMP flood, SYN flood).

  2. Protocol Exploitation: Exploiting protocol vulnerabilities to consume resources (e.g., Slowloris holding connections open).

  3. Application Layer Attacks: Targeting specific web applications (e.g., HTTP GET/POST floods).

  4. Wireless-Specific: Deauthentication attacks (forging deauth frames in Wi-Fi), jamming (RF interference at physical layer).

B. Military Security Models

• Primary Objectives (CIA Triad in a Command Context):

  1. Confidentiality: Ensure sensitive information is accessible only to authorized personnel (need-to-know basis). Uses classification levels (Top Secret, Secret, etc.).

  2. Integrity: Protect information from unauthorized modification. Ensures data is trustworthy and accurate.

  3. Availability: Ensure information systems and services are reliable and accessible to authorized users when needed, especially during missions.

• Role of Hierarchical Command Structures:

  • Enforces Access Control: Clear chain of command defines who has authority to access what information and systems (based on rank/clearance).

  • Policy Enforcement: Centralized command can mandate and monitor compliance with security policies (e.g., encryption use, physical security).

  • Accountability: Clear lines of responsibility; actions can be traced up the chain.

  • Compartmentalization: Limits knowledge of sensitive operations to only those directly involved, reducing insider threat risk.

[!TIP] Exam Focus: Link hierarchy directly to enforcing access control, policy, and accountability. It's not just about chain of command; it's a security enforcement mechanism.

SHORT NOTES ON ADDITIONAL FREQUENT QUESTIONS

Write a short note on Wireless Local Area Network (WLAN)

A WLAN is a local-area network that uses wireless communication (radio waves) to connect devices within a limited area (home, office, campus). It typically follows a star topology with an Access Point (AP) as the central hub. Clients communicate with the AP, which bridges traffic to the wired network (Distribution System). Based on IEEE 802.11 standards (Wi-Fi), WLANs provide mobility, ease of installation, and scalability. Key components include wireless clients, APs, and antennas. Security is a major concern, addressed by protocols like WPA2/WPA3. Common applications include internet access in public hotspots, enterprise networks, and smart homes.

Write a short note on TCP over Wireless Networks

Standard TCP (Transmission Control Protocol) is designed for reliable, fixed networks with low bit error rates (BER). It performs poorly in wireless environments due to: (1) High BER causing packet loss, which TCP misinterprets as congestion and reduces window size unnecessarily; (2) Large/variable RTT affecting retransmission timers; (3) Frequent handoffs causing connection breaks. Adaptations include: splitting TCP connections (e.g., at base station), using local retransmission to hide wireless loss, or employing TCP variants (e.g., TCP Westwood) that distinguish between congestion and error loss. The core challenge is making TCP's congestion control wireless-aware.

Write a short note on Universal Mobile Telecommunication System (UMTS)

UMTS is the 3G standard developed by 3GPP, evolving from 2G GSM to provide global mobile broadband. Its architecture introduces the UTRAN (UMTS Terrestrial Radio Access Network), replacing GSM's BSS with Node B (base station) and RNC (Radio Network Controller). The core network evolves to support both circuit-switched (for voice) and packet-switched domains (for data), with new nodes SGSN and GGSN. Key objectives were to deliver higher data rates (up to 2 Mbps), support multimedia services (video calling), and enable seamless international roaming. It uses WCDMA as its air interface, providing better spectral efficiency than 2G.

Write a short note on Denial of Service (DoS)

A Denial of Service (DoS) attack aims to disrupt the availability of a service or resource for legitimate users. The attacker overwhelms the target with a flood of illegitimate requests or exploits protocol vulnerabilities to consume critical resources (bandwidth, CPU, memory). A Distributed DoS (DDoS) uses a botnet of compromised devices to launch a coordinated attack from multiple sources, making mitigation harder. Common methods include flooding attacks (SYN flood, HTTP flood), protocol attacks (Slowloris), and in wireless networks, deauthentication/disassociation attacks or jamming. The primary impact is service unavailability, leading to financial loss and reputational damage.