Computer Worms and Trojans Quiz

Computer Memory Unit of Measurement

• Various units are used to measure computer memory.

Types of Memory

• Primary Memory:
  • RAM (Random Access Memory)
    • Has two types: Dynamic RAM (DRAM) and Static RAM (SRAM)
    • DRAM:
      • A cell of capacitors and transistors holds a single bit of information
      • Considered to be very dense, allowing a lot of data to be stored on a small chip
      • Requires constant refreshing by the memory controller
    • SRAM:
      • Maintains its contents for as long as power is applied
      • Uses a cluster of six transistors to store a single bit
      • Considered to be lower in density, it is larger but more expensive than a comparable DRAM chip
  • ROM (Read Only Memory)
    • Does not need to be refreshed
    • Used to store permanent, or semi-permanent data that persists even while the system is off
    • Three types of ROM Chips:
      • PROM (Programmable Read Only Memory)
      • EPROM (Erasable Programmable Read Only Memory)
      • EEPROM (Electrically Erasable Programmable Read Only Memory)

Secondary Memory

• Where data is stored in the computer so it can be easily retrieved later
• How caching works:
  • The cache controller anticipates what data will be required next
  • Three levels of processor cache exist in modern computers:
    • Level 1 (L1) cache:
      • Size ranges about 256KB or more
      • Integrated into the CPU
      • Runs at the full core speed of the CPU
      • Very expensive to manufacture
    • Level 2 (L2) cache:
      • Approximately 1MB of storage
      • Runs at full processor speed
      • Acts as secondary buffer between system memory and CPU
      • Also expensive to manufacture
    • Level 3 (L3) cache:
      • Resides on the CPU – some older CPU’s have it on the motherboard
      • Size of the Cache is approximately 6MB to 8MB
• Two ways of accessing a secondary memory:
  • Sequential
  • Direct

Types of Secondary Memory

• Hard Disks
• Optical Drives
• Magnetic Tape
• USB Thumb Drive

Tertiary Memory

• This type of Memory is not attached to the computer
• Types of Tertiary Memory:
  • Cloud Storage
  • Network Attached Storage (NAS)

Virtual Memory

• Enhances performance by providing greater memory capacity, without the expense of adding main memory
• Instead, a portion of a disk drive serves as an extension of main memory
• A physical address is the actual memory address of physical memory

Computer Maintenance

• Avoid Overheating
• Remove Unwanted Programs
• Defragment the Hard Drive (can be used for Mechanical hard drives only, not Solid-State Drives)
• Recover Wasted Disk Space
• Disk cleanup
• System Restore
• Data Backups and Recovery

Data Backups and Recovery

• Unstructured or “one-off” Images
• Full Differential
• Incremental
• Full back up of the entire structure of the hard drive including the OS
• Full back up of the target data except the OS
• Backup new and changed files since the last full back up

MS Excel

• Worksheet:
  • Contains a grid of small boxes, each box(cell) stores a piece of data
  • Columns are A - … and Rows are 1 – 1048576
  • Four basic types of data used in MS Excel: Numeric value, Text Data, A formula, An error message
• Formula Basics:
  • Operator:
    • /
    • ^
    • &
  • Logical Operators:
    • =
    • >
    • <
    • >=
  • Worms:
    • May carry a variety of payloads and may appear to behave as a virus
    • Worms generally don’t cause any harm to their host(computer) but their replicating nature consumes hard disk space, slowing down the host computer
    • Spread through (across) vulnerable network connections or through storage media
    • Payloads are often Trojan programs
  • Trojans:
    • A Trojan is a type of virus; it “hides” inside a useful program, and performs “operations” in the background that the user is unaware of
    • May record keystrokes to collect passwords or other sensitive data or load malicious software
    • Take advantage of security holes and create a means for remote users to control the computer (backdoor access)
  • Ransomware:
    • A type of malware; it encrypts the data on your hard drive/backup devices and prevents you from using your computer
    • It is a tool that can be used by governments to attack the infrastructure of another country
    • To unencrypt your computer, you often have to pay a “ransom”
    • Often payment is demanded/made in bitcoins, a digital currency
  • Spyware:
    • Bots
    • Botnet (Bots) is a series of computers standing by to execute a coordinated attack against a target (i.e.