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Network Security & Database Vulnerabilities

  1. TCP/IP Framework
  2. Basics of IP Addressing and the OSI Model
  3. Introduction to Databases
  4. Deep Dive - Injection Vulnerability

TCP/IP Framework

  • IDS (Intrusion Detection System) - network security tech built for detecting vulnerability exploits against the system; listen-only device as it monitors traffic and reports results to administrator.

  • IPS (Intrusion Prevention System) - network security and threat prevention tech that examines network traffic flows to detect & prevent vulnerability exploits; it is placed inline (unlike IDS), behind firewall, and in direct communication path for active prevention.

  • Threat detection types:

    • Signature-based
    • Anomaly-based
    • Host-based
    • Network-based

  • NAT (Network Address Translation) - remapping one IP address space into another for security.

  • Types of NAT:

    • Static - one-to-one mapping between local & global addresses.

    • Dynamic - maps unregistered IP addresses to registered IP addresses from a pool.

    • Overloading - maps multiple unregistered IP addresses to a single registered IP address, many-to-one, using different ports; also known as Port Address Translation.

  • ARP (Address Resolution Protocol) - process of using layer 3 addresses (IP address) to determine layer 2 addresses (MAC address).

Basics of IP Addressing and the OSI Model

  • IPv4 - 32 bits address, divided in 4 octets.

  • Classful addressing:

    • Class A - 0.0.0.0 - 127.255.255.255 - unicast/special

    • Class B - 128.0.0.0 - 191.255.255.255 - unicast/special

    • Class C - 192.0.0.0 - 223.0.0.0 - unicast/special

    • Class D - 224.0.0.0 - 239.255.255.255 - multicast

    • Class E - 240.0.0.0 - 255.255.255.255 - reserved

  • IPv6 - 128 bits address, divided in 8 hexadecimal values (16 bits each).

  • TCP (Transmission Control Protocol) - connection-oriented, reliable; ordered, segmented data with flow control.

  • UDP (User Datagram Protocol) - connectionless, unreliable; unordered, datagram data without flow control.

  • NGFW (next-generation firewall) - combines traditional firewall with other network device filtering functionality, such as IPS and website filtering; able to monitor the traffic from layer 2 to layer 7.

Introduction to Databases

  • Data source types:

    • Distributed databases (Structured)
    • Data warehouses (Structured)
    • Big data (Semi-structured)
    • File shares (Unstructured)

  • Types of structured data:

    • Flat file databases - all info is stored in one table

    • Relational databases - data in multiple tables, linked to each other using keys

Deep Dive - Injection Vulnerability

  • Injection flaws allow attackers to relay malicious code through vulnerable app to another system; may allow full takeover of system.

  • OS command injection - abuse of vulnerable app functionality that causes execution of specified OS commands; due to lack of input sanitization, and unsafe execution of OS commands.

  • Prevention of OS command injection:

    • Do not execute OS commands, use built-in commands or 3rd party libraries
    • Run at least possible privilege level
    • Do not run commands through shell interpreters
    • Use explicit paths when running executables
    • Use safer functions when running system commands
    • Do not let user input reach command execution unchanged
    • Sanitize user input with strict whitelists, not blacklists

  • SQL injection - abuse of vulnerable app functionality that causes execution of specified SQL queries.

  • Types of SQL injection:

    • Error-based
    • UNION-based
    • Blind injection
    • Out of Band

  • Prevention of SQL injection:

    • Use prepared statements
    • Sanitize user input
    • Do not expose native database errors to the user
    • Limit database user permissions
    • Use stored procedures
    • Use ORM (Object-relational mapping) libraries