System software and security

System software and security

1. Network threats

   • Malware and worms
     • Worms: a program that runs by itself, infects vulnerable computers, and then sends itself to others. It may scan the internet for computers it can enter
     • Virus: This is a program that needs another host program to run on. It is sent along with the host to other computers, and so on.
     • Criminals sometimes leave a USB stick contaminated with a virus lying, for example, in the car park of a company that they wish to infect with a virus or steal data from An unsuspecting employee may pick it up and insert it into their computer
   • Social engineering
     • Social engineering takes advantage of human nature, conning people into giving away private details
     • Phishing: You receive what appears to be a legitimate email, concerning a paypal or ebay account, but really it is a scam, asking for money. There may be scams like this that target emotional aspects, like saying that "this person needs help; we need you passwords and usernames for this account to help them.
       • Some phishing emails may download malware.
       • Greeting: The phishers don’t know your name – just your email address, so the greeting is not personalised The sender’s address is often a variation on a genuine address Forged link: The link looks genuine, but it may not link to the website given. Roll your mouse over it to check Request for personal information: Genuine organisations never do this Sense of urgency: Criminals try to persuade you that something bad will happen if you don’t act fast Poor spelling and grammar
     • Shoulder surfing: this is directly observing passwords and pins, by camera, heat-sensetive keypads, or just standing behind them in a queue
   • Brute force
     • In a brute force attack, the attacker will go through a list of passwords, or try every possible password with a computer until the right password is found.
   • DDoS attacks
     • A DoS attack attempts to flood a website server with an overwhelming number of data requests It may flood the victim’s site with spam emails (an “email bomb”) or disrupt access to a victim’s website or entire geographical area by reconfiguring software to crash network sites
     • The motive is often revenge, blackmail or terrorism
   • Eavesdropping
     • Digital stalking
       • Using GPS and other in phone apps to track someone.
     • Communications tapping
       • Hacking into communications and intercepting data packages
   • SQL injection
     • SQL is a database query language SQL injection takes advantage of web input forms to access or destroy data SQL commands can be input into web forms instead of the expected ‘real’ data This can be interpreted by vulnerable web applications as an additional instruction to operate in the hacker’s favour

2. Operating system software

   • Penetration testing
     • Purposefully lets "white hat hackers attack the system to find flaws, and fix them.
     • White box/black box testing
       • In white box the hacker is given the information an insider may have, such as computer types, usernames, passwords etc
       • Black box testing is when the hacker has little information on a system, such as the amount outsiders may have.
   • White/black hat hackers
     • whitehathackers
       • Ethical. Hired by companies to check systems for weaknesses.
     • Blackhathackers
       • Non-ethical. Will sell information about a groups weaknesses
         • Or even use the information themselves, later selling banking passwords, user information etc on the internet
     • ‘Grey-hats’ fall somewhere in between black and white hats Grey hats will frequently seek out system vulnerabilities without authorisation from the system owners Any flaws they find may either be reported for a ‘ransom’ fee or broadcast on the Internet without actually doing anything to take advantage of the flaws themselves
   • Audit trails
     • Digital trails left behind on a network. These generally store information about where a user went on the network, what they did, what time they did it, and who it was. It can also store information about people attempting to hack or enter the system.
       • Through this, motives may emerge
     • Intrusion detection systems can record and alert administrators in real time
   • Acceptable use policy
     • Most organisations have an Acceptable Use Policy which employees (or students) are required to sign and agree to before using the network system
       • It is legally binding
   • Passwords
     • Use a minimum of eight characters Use a mixture of numbers, lowercase and uppercase characters Include symbols such as &, !, #, % Do not include your name, DOB or personal details Create a password based on a memorable phrase and exchange letters for numbers or symbols e.g. Brdu8#Jw4g
   • Protect your device
     • Anti-malware software
       • Use auto-updates to keep your device free from new viruses
     • Firewalls
       • Different to anti-malware software, firewalls scan incoming packets, either blocking them or letting them through depending on the data inside, e.g. whether it has viruses in
       • Firewalls act as filters between a trusted server, and an unknown one
     • Proxy server
       • This can be run on a dedicated machine or general purpose server, and acts as a firewall
   • Access rights
     • Access rights can be set on anything. They stop certain people entering certain things, or using them. High level people within an organisation have more access rights than others.
   • Encryption
     • Intercepted messages can be read if they do not have encryption
     • Encryption and decryption
       • Encryption
       • Decryption
     • Types of cipher and code
       • Cipher
         • This is done on a letter level
       • Code
         • This is done on word level
       • Symmetric
         • The same key is needed at both ends
         • Simple shift ciphers are an example of this
       • Asymmetric
         • These need a public key and a private key. The public key is made known in a large server. This is used by the computer (person B) to send messages to person A, who owns that public key. Person B also has a public key. Person A then uses their private key to decode the message. Only person A knows the private key.
   • HTTPS
     • This is a secure website

3. Identifying and preventing vulnerablities

   • Software that ... manages a computer’s hardware and provides a user interface
   • Provides a user interface
     • This means that we can understand the computer, and use it easily, instead of needing to code every instruction
     • Types
       • GUI: Graphical User Interface
         • Wiimp interfaces
           • Stands for: Windows, Icons, Menus and Pointers
             • Pointers
               • User can click on icons using a pointer or cursor Icons representing functions mean less need to type instructions – just click on an icon or menu item Right-clicking brings up context-sensitive menus Different shaped pointers have different uses
       • Menu-driven
         • Less commonly used but still prevalent in some areas. Used in music playing devices and apps.
       • CLI: Command Line Interface
         • All commands must be typed in as text. No graphics. Quicker for expert users who know the commands. Takes less space on the disk and in RAM
       • Voice activated
       • Real time
         • sensors detect inputs, actuators output actions
   • Manages
     • Memory
       • To run a program, the computer must copy the program from storage into main memory
         • 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 It must not overwrite existing programs
     • Multitasking
       • You may use your computer to do several tasks at the same time with different software: homework, playing music, messaging friends...
         • There are many background processes running on the computer as well
         • They are taking it in turns to get processor time to execute instructions
         • The OS must manage how the processes share the processor
     • Peripherals
       • Getting input and sending output Copying files from disk to main memory Copy data files back to secondary storage
       • Device drivers
         • This is a program which controls a peripheral device such as a printer, CD-ROM drive, etc
         • Each device communicates with the OS via its own driver Many device drivers are built into the operating system but if you buy a brand new type of device, it will be supplied with a driver, which you will need to install
       • Access speed is relatively slow
       • Sending data to a printer
         • The computer can send data thousands of times faster than the printer can print it The computer sends the printer output to a print buffer, a special area of memory in either the computer or the printer, at full speed
           • From here, it is transmitted it to the printer, typically a page at a time The print buffer may store a number of jobs waiting to be printed
     • Files
       • The operating system: manages where on the disk files are written keeps track of where they are so they can be retrieved makes sure no file overwrites another file
     • User Access Rights
       • Usernames and passwords
         • If a computer is used by more than one person, each user should be able to see only their own files Users and system administrators have different levels of access rights Some users may be allowed to read files but not edit them
     • Interrupts
       • These are signals sent to the CPU by external devices to indicate an event that needs immediate attention
         • The CPU suspends current activities and executes appropriate instructions
       • Hardware interrupts are created by hardware: printer out of ink, something out of power
       • Software interrupts are created by programs e.g. a divide-by-zero error will cause a calculation to be abandoned and an error message displayed

4. Utility software

   • The functions of operating systems
     • provision of a user interface
     • memory management
     • multitasking
     • disk/peripheral management
     • user management / security
     • file management
   • Operating system
     • This controls and manages the computer system
     • Utilities make it easier to use, and give extra functions. They can be stand-alone software, or part of the system
   • Encryption software
     • Used by banking websites, government agencies, etc
     • Can encrypt files on hard drives and USBs, web communication, and encyrpt data on a database
   • Disk organisation
     • File management and transfer, disk defragmentation
     • Cut, Copy Paste, Delete
   • Data fragmentation
     • When you save a large file it may not fit on the disk in consecutive memory locations The file is referred to as “fragmented”
       • Retrieving data from the file takes more processing More processing means reduced performance Defragmenting the hard disk reorganises files so they are stored together Processing time reduces so performance is improved Free space is also in one place so new files do not have to be fragmented
   • Data compression
     • WinZip
     • Compress or decompress files or folders. This reduces the bandwidth and data consumption needed to download files. It can fit files into strict formats.
   • Backing up data
     • Backup and restore utilities create backup files regularly.
       • This keeps data safe
     • Backing up files is vital to protect against loss from accidental or malicious damage, corruption or natural disaster
     • Types of backup
       • Full backup
         • Complete backup of everything which can be restored independently of any other backup Takes greater time and disk space to create the backup
       • Incremental backup
         • Records only the changes made since the last backup A entire chain of backups is required to fully restore files