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Computer viruses and its types in detail
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- 2. Computer Security Risks What is a computer security risk? Event or action that causes loss of or damage to computer system Anything on your computer that may damage or steal your data or allow someone else to access your computer, without your knowledge or consent.
- 3. Virus A computervirus is a computer program that can replicate itself and spread from one computer to another. The term "virus" is also commonly but misused to refer to other types of malware, including but not limited to adware and spyware programs that do not have the reproductive ability. A true virus can spread from one computer to another (in some form of executable code) when its host is taken to the target computer; for instance because a user sent it over a network or the Internet, or carried it on a removable medium such as a floppy disk, CD, DVD, or USB drive.
- 4. Who Writes Viruses-and Why? Viruses can be written by anyone It could include researchers for demonstration purposes In some cases, they can be written by pranksters. These viruses get passed around and can be altered by other people.
- 5. Are All ComputerViruses Harmful? Every computer virus ever written takes up disk space Many of them are able to remain in the computer's memory taking control Some viruses are written to halt the computer There are viruses created to deliberately destroy data on the disk
- 6. What do theydo? slower processing decreased memory a disk drive LED lighting up for no apparent reason a screen going blank when you touch a certain letter on your keyboard delete data copy password
- 7. Types of Virus Not all computer viruses behave, replicate, or infect the same way. There are several different categories of viruses and malware. Below I list and discuss some of the most common types of computer viruses. Trojan Horse Worms Boot sector Virus: Macro Virus Memory Resident Viruses Rootkit Virus Polymorphic Viruses Logic Bombs/Time Bombs
- 8. Trojan Horse ATrojan Horse Virus is a type of malware that downloads onto a computer disguised as a legitimate program. The delivery method typically sees an attacker use social engineering to hide malicious code within legitimate software to try and gain users' system access with their software. A simple way to answer the question "what is Trojan" is it is a type of malware that typically gets hidden as an attachment in an email or a free-to-download file, then transfers onto the user’s device. Once downloaded, the malicious code will execute the task the attacker designed it for, such as gain backdoor access to corporate systems, spy on users’ online activity, or steal sensitive data. A Trojan Horse neither replicates nor copies itself, but causes damage or compromises the security of the computer. A Trojan Horse must be sent by someone or carried by another program and may arrive in the form of a joke program or software of some sort.
- 9. Worms A computerworm is a type of malware whose primary function is to self-replicate and infect other computers while remaining active on infected systems. A computer worm duplicates itself to spread to uninfected computers. It often does this by exploiting parts of an operating system that are automatic and invisible to the user. It is common for worms to be noticed only when their uncontrolled replication consumes system resources, slowing or halting other tasks. the worm virus exploits vulnerabilities in your security software to steal sensitive information, install backdoors that can be used to access the system, corrupt files, and do other kinds of harm.
- 10. Types of viruscontinued …… Bootsector Virus: Boot sector viruses infect or substitute their own code for either the DOS boot sector or the Master Boot Record (MBR) of a PC. The MBR is a small program that runs every time the computer starts up. It controls the boot sequence and determines which partition the computer boots from. The MBR generally resides on the first sector of the hard disk. Since the MBR executes every time a computer is started, a boot sector virus is extremely dangerous. Once the boot code on the drive is infected, the virus will be loaded into memory on every startup. From memory, the boot virus can spread to every disk that the system reads. Boot sector viruses are typically very difficult to remove, as most antivirus programs cannot clean the MBR while Windows is running. In most cases, it takes bootable antivirus disks such as a Symantec/Norton AntiVirus (SAV/NAV) rescue set to properly remove a boot sector virus. Some common boot sector viruses include Monkey, NYB (also known as B1), Stoned, and Form.
- 11. Bootsector virus Aboot sector virus can cause a variety of boot or data retrieval problems. In some cases, data disappear from entire partitions. In other cases, the computer suddenly becomes unstable. Often the infected computer fails to start up or to find the hard drive. Also, error messages such as "Invalid system disk" may become prevalent.
- 12. Macro Virus: Macroviruses are viruses that use another application's macro programming language to distribute themselves. They infect documents such as MS Word or MS Excel and are typically spread to other similar documents. Some of these viruses cause abnormalities in text documents, such as missing or inserted words, while others access email accounts and send out copies of infected files to all of a user's contacts, who in turn open and access these files because they come from a trusted source. Memory Resident Viruses: Memory Resident Viruses reside in a computers volitale memory (RAM). They are initiated from a virus which runs on the computer and they stay in memory after it's initiating program closes. A few examples of this kind of virus are Jerusalem Virus, Onehalf virus, Magistr, Junkie, Satanbug etc.
- 13. Types of viruscontinued …… Rootkit Virus: A rootkit virus is an undetectable virus which attempts to allow someone to gain control of a computer system. The term rootkit comes from the linux administrator root user. These viruses are usually installed by trojans and are normally disguised as operating system files. Polymorphic Viruses: A polymorphic virus not only replicates itself by creating multiple files of itself, but it also changes it's digital signature every time it replicates. This makes it difficult for less sophisticated antivirus software to detect. Logic Bombs/Time Bombs: These are viruses which are programmed to initiate at a specific date or when a specific event occurs. Some examples are a virus which deletes your photos on Halloween, or a virus which deletes a database table if a certain employee gets fired.
- 14. Spyware Software thatperforms certain behaviors, generally without appropriately obtaining your consent first, such as: Advertising Collecting personal information Changing the configuration of your computer
- 15. Spam Short for “malwarespam” or “malicious spam,” malspam is a spam message that delivers malware to your device. Unsuspecting readers who click on a link or open an email attachment end up with some type of malware including ransomware, torjans, bots, info-stealers, crypto miners, spyware, and keyloggers.
- 16. Example We suspectan unauthorized transaction on your account. To ensure that your account is not compromised, please click the link below and confirm your identity.” “During our regular verification of accounts, we couldn’t verify your information. Please click here to update and verify your information.” “We are updating all email accounts on our mail server. Please click the link below and update your username and password. If you don’t reply within 48 hours your account will be closed”
- 17. Hacker A hackeris a person who breaks into computers, usually by gaining access to administrative controls most hackers are thieves, looking for personal data or bank/ credit card information White hat hacker Black hat hacker
- 18. Prevention against viruses To prevent your computer from contracting a virus, use a virus protection program. Keep up-dated on what viruses are going around. Don't open email that is suspicious or that you don't recognize the senders name. Activate firewall Always back up your files! If your computer does contract a virus, be prepared to reformat and start all over again!
- 19. Stand-Alone Utility Programs What is a virus? Potentially damaging computer program Affects computer without user’s knowledge SIGNS OF SIGNS OF VIRUS VIRUS INFECTION INFECTION • An unusual message or image is displayed on the computer screen • An unusual sound or music plays randomly • The available memory is less than what should be available • A program or file suddenly is missing • An unknown program or file mysteriously appears • The size of a file changes without explanation • A file becomes corrupted • A program or file does not work properly • System properties change •The operating system runs much slower than usual
- 20. Stand-Alone Utility Programs What is an antivirus program? Identifies and removes viruses in memory, storage media, and incoming files Must be updated frequently Identifies and removes computer viruses Most also protect against worms and Trojan horses
- 21. What isan antivirus program?
- 22. What areviruses, worms, and Trojan horses? Virus Virus is a potentially damaging computer program Worm Worm copies itself repeatedly, using up resources and possibly shutting down computer or network Trojan horse Trojan horse hides within or looks like legitimate program until triggered Payload (destructive event) that is delivered when you open file, run infected program, or boot computer with infected disk in disk drive Can spread and damage files Does not replicate itself on other computers
- 23. How can avirus spread through an e-mail message? Step 1. Unscrupulous programmers create a virus program. They hide the virus in a Word document and attach the Word document to an e- mail message. Step 2. They use the Internet to send the e-mail message to thousands of users around the world. Step 3b. Other users do not recognize the name of the sender of the e-mail message. These users do not open the e-mail message. Instead they delete the e-mail message. These users’ computers are not infected with the virus. Step 3a. Some users open the attachment and their computers become infected with the virus.
- 24. Keeps file in separate areaof hard disk How does an antivirus program inoculate a program file? Records Records information information about program such about program such as file size and as file size and creation creation date date Attempts Attempts to remove to remove any detected any detected virus virus Uses Uses information information to detect if to detect if virus tampers virus tampers with file with file Quarantines Quarantines infected infected files that it files that it cannot cannot remove remove
- 25. What isa firewall? Security system consisting of hardware and/or software that prevents unauthorized intrusion A firewall is a network security device that monitors incoming and outgoing network traffic and decides whether to allow or block specific traffic based on a defined set of security rules. Firewalls have been a first line of defense in network security for over 25 years. They establish a barrier between secured and controlled internal networks that can be trusted and untrusted outside networks, such as the Internet. A firewall can be hardware, software, or both.
- 26. Unauthorized Access andUse What are other ways to protect your personal computer? Disable file and printer sharing on Internet connection
- 27. Tips for security Whatare some tips for preventing virus, worm, and Trojan horse infections? Install a personal firewall program If the antivirus program flags an e-mail attachment as infected, delete the attachment immediately Never start a computer with removable media inserted Never open an e-mail attachment unless you are expecting it and it is from a trusted source Install an antivirus program on all of your computers Check all downloaded programs for viruses, worms, or Trojan horses
- 28. Backing Up —The Ultimate Safeguard What is a backup? Duplicate of file, program, or disk Full backup Full backup all files in computer Selective backup Selective backup select which files to back up Three-generation Three-generation backup backup preserves three copies of important files In case of system failure or corrupted files, restore restore files by copying to original location
- 29. Information Privacy Whatare spyware, adware, and spam? Spyware is program placed on computer without user’s knowledge Adware is a program that displays online advertisements Spam is bogus e-mail message sent to many recipients
- 30. Information Privacy Howcan you control spam? Collects spam in central location that you can view any time Service that blocks e-mail messages from designated sources E-mail filtering E-mail filtering Sometimes removes valid e-mail messages Attempts to remove spam Anti-spam program Anti-spam program
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