Unit 4 revision Network security and Systems Software

Unit 4 revision Network security and Systems Software

1. Network threats

   • Malware
     • Executable programs that run on a computer
     • Viruses
       • Replicate their code in other programs
       • Infect other computers
       • Harm the computers by deleting, corrupting or modifying files
       • Infect computers
     • Worms
       • replicates itself in order to spread to other computers
       • might cause no damage to the attacked computers
       • Slow down networks and computers
     • Trojan horses
       • They have a program, game or cracked file which is something the user wants
       • They have negative program code which cause damage, takes control or provides access to the computer
     • Ransomware
       • Holds hostage by locking or encrypting access to it
       • if data encrypted, not even a cyber security professional unless backups are available
       • ransom is paid to the attacker, access is restored
   • Exploiting vulnerabilites
     • Social engineering
       • obtain confidential information by asking people for it
     • shoulder surfing
       • getting information or passwords by observing as someone type them in
     • Phishing
       • Emails, text or phone calls are sent to users commonly pretending to be from a bank or website
     • DoS
       • hacker will use or infect a computer
       • DDoS
         • Many computers are used to send the requests
     • Man-in-the-middle
       • allows the attacker to intercept communications between the user and server
     • Free USB Stick
       • Criminals leave a USB stick containing malware in a public place such as a company car
   • Brute force attacks
     • a hacker will try every combinations of passwords until the correct passwords is found
   • SQL injection
     • SQL is a database query language
     • takes advantage of web input forms to access or destroy data

2. Preventing Vulnerabilities

   • anti-malware software
     • detect malware such as trojan, viruses, worms, and spyware
     • when a virus or new malware is detected it is sent to the anti-virus company
     • they verify it is malware then create a signature of the virus
     • Then they add to their virus database and tell computers to run an update
   • encryption
     • a way of securing data so that it cannot be read without the encryption key
     • passwords stored by website are almost always stored in an encryption form
     • if a hacker obtains the data in the password database, they won't be able to easily read the passwords
     • devices and computers can also have their storage and hard disk data encrypted
     • encryption of transmitted data
       • websites use HTTPS
       • web browser sends its key and form data, encrypting it with the server's key
       • The server encrypts the web page you request using your web browser's key
     • encryption on single file
       • files can be encrypted individually on a computer using a password
       • this can only be viewed by people who have the password
       • softeare such as zip files allow encryption to be applied
     • encryption of drives
       • ordinary computers drives can be encrypted so that a password is needed to access the information
   • firewalls
     • a trusted network from an untrusted network
     • data is sent around a network in small packets of information
     • these packets are checked to see where they are coming from and going to
     • firewall may build into your hardware
     • firewall will detect packets from malicious computers
     • firewall features
       • prevents attackers from gaining access to computers on a network
       • can block certain malicious computers by filtering packets from a certain IP address
       • can prevent access to certain ports on the network
       • malicious and inappropriate networks can be blocked
       • dedicated firewalls are expensive
       • software firewalls will slow down a computer
   • user access levels
     • access rights may be set on disks, folders and even individual files
   • Passwords
     • Policies
       • Minimum length
       • At least 1 lower case and capital case
       • include number
       • at least on special symbol
       • change password every month
   • physical security

3. system software

   • System software is the software that provides a platform for other software to work
   • operating system
     • manage computer hardware, users and the resources used by software
     • responsible for:
       • user interface
         • provide a method for users to interact with a computer
         • GUI
           • Graphic user interface
             • Desktop interface
               • pointers
               • windows
               • menus
               • icons
               • drag and drop
             • smartphone and touch interfaces
               • no pointers in general as they cannot be seen under a finger
               • windows (for apps) generally take up the full screen
         • Menu-driven interface
           • often used by devices that have a dedicated function including:
             • MP3 players
             • ATM machines
             • Self service machine
         • CLI:Command Line Interface
           • Text commands are entered into the interface
           • requires very little processing and can save on the need for an expensive graphics card
           • For expert users who know the commands it can be far faster to enter commands than using a mouse
         • Voice activated
         • Real-time
           • sensors detect inputs
       • memory management
         • Data used by the program is copied into main memory
         • the operating system keeps a record of where each program and its data are located
         • the operating system will make sure not to overwrite existing programs and data
       • multi-tasking
         • when operating system manages many tasks happening at the same time
         • e.g. having a web browser open whilst playing music
       • peripheral management and drivers
         • the operating system must manage getting inputs and sending outputs to peripheral devices
         • peripherals include mice, keyboard, printers, display, digital cameras, and graphics tablets
         • device driver is a program that controls peripheral devices such as printers, mice and displays
           • sending data to a printer
             • the computer can send data to a printer much faster than it can be printed
             • the data will be sent to a print queue or buffer which is a special area of memory in a computer print server or the printer itself
       • user management
         • responsible for log-in
         • access rights
           • users and system administrators have different levels of access rights
           • some users may be allowed to read but not edit
       • file management
         • Naming files
         • allocating files to folders
         • moving files
         • saving files
         • copying files
         • deleting files
       • interrupts
         • signals sent to the CPU by external devices to indicate an event that needs immediate attention
         • software
           • generated by programs
           • divide by zero error
         • hardware
           • printer out of paper
           • generated by hardware devices

4. utility software

   • perform extra functionality and housekeeping tasks that keep computers running efficiently
   • encryption software
     • encode text so that it cannot be understood without knowing the key to decode it
     • encryption tools
       • encrypts entire hard disks so that the data cannot be understood if the computer is stolen
       • encrypt files and folders on a portable disk such as a USB
       • encrypt communication with cables
       • encrypt data in an organinsation's database - especially sensitive data such as passwords
   • disk defragmentaiton
     • when save a large file it may not fit on the disk in consecutive memory locations
     • defragment the hard disk reorganises files so they are stored together
     • read times are far faster and free space is also in one space so new files do not need to be fragmented
   • data compression software
     • reduces the amount of storage space needed on a disk
     • reduces the amount of data that is sent
     • more data can be stored on backup media