What Is Computer Virus And Types Of Computer Virus Pdf
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- 9 types of malware and how to recognize them
- What is a computer virus?
People tend to play fast and loose with security terminology. However, it's important to get your malware classifications straight because knowing how various types of malware spread is vital to containing and removing them. This concise malware bestiary will help you get your malware terms right when you hang out with geeks.
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People tend to play fast and loose with security terminology. However, it's important to get your malware classifications straight because knowing how various types of malware spread is vital to containing and removing them. This concise malware bestiary will help you get your malware terms right when you hang out with geeks. A computer virus is what most of the media and regular end-users call every malware program reported in the news.
Fortunately, most malware programs aren't viruses. A computer virus modifies other legitimate host files or pointers to them in such a way that when a victim's file is executed, the virus is also executed. That's a good thing: Viruses are the only type of malware that "infects" other files. That makes them particularly hard to clean up because the malware must be executed from the legitimate program.
This has always been nontrivial, and today it's almost impossible. The best antivirus programs struggle with doing it correctly and in many if not most cases will simply quarantine or delete the infected file instead. Worms have been around even longer than computer viruses, all the way back to mainframe days. Email brought them into fashion in the late s, and for nearly a decade, computer security pros were besieged by malicious worms that arrived as message attachments. One person would open a wormed email and the entire company would be infected in short order.
The distinctive trait of the computer worm is that it's self-replicating. Take the notorious Iloveyou worm : When it went off, it hit nearly every email user in the world, overloaded phone systems with fraudulently sent texts , brought down television networks, and even delayed my daily afternoon paper for half a day. What makes an effective worm so devastating is its ability to spread without end-user action. Viruses, by contrast, require that an end-user at least kick it off, before it can try to infect other innocent files and users.
Worms exploit other files and programs to do the dirty work. For example, the SQL Slammer worm used a patched vulnerability in Microsoft SQL to incur buffer overflows on nearly every unpatched SQL server connected to the internet in about 10 minutes, a speed record that still stands today. Computer worms have been replaced by Trojan malware programs as the weapon of choice for hackers. Trojans masquerade as legitimate programs, but they contain malicious instructions. They've been around forever, even longer than computer viruses, but have taken hold of current computers more than any other type of malware.
A Trojan must be executed by its victim to do its work. Trojans usually arrive via email or are pushed on users when they visit infected websites. The most popular Trojan type is the fake antivirus program, which pops up and claims you're infected, then instructs you to run a program to clean your PC.
Users swallow the bait and the Trojan takes root. Remote access Trojans RATs in particular have become popular among cybercriminals. RATs allow the attacker to take remote control over the victim's computer, often with the intent to move laterally and infect an entire network. This type of Trojan is designed to avoid detection.
Threat actors don't even need to write their own. Hundred of off-the-shelf RATs are available in underground marketplaces. Trojans are hard to defend against for two reasons: They're easy to write cyber criminals routinely produce and hawk Trojan-building kits and spread by tricking end-users — which a patch, firewall, and other traditional defense cannot stop.
Malware writers pump out Trojans by the millions each month. Antimalware vendors try their best to fight Trojans, but there are too many signatures to keep up with. Today, most malware is a combination of traditional malicious programs, often including parts of Trojans and worms and occasionally a virus.
Usually the malware program appears to the end-user as a Trojan, but once executed, it attacks other victims over the network like a worm. Many of today's malware programs are considered rootkits or stealth programs. Essentially, malware programs attempt to modify the underlying operating system to take ultimate control and hide from antimalware programs.
To get rid of these types of programs, you must remove the controlling component from memory, beginning with the antimalware scan. Botmasters have one or more "command and control" servers that bot clients check into to receive their updated instructions. Botnets range in size from a few thousand compromised computers to huge networks with hundreds of thousands of systems under the control of a single botnet master.
These botnets are often rented out to other criminals who then use them for their own nefarious purposes. Malware programs that encrypt your data and hold it as hostage waiting for a cryptocurrency pay off has been a huge percentage of the malware for the last few years, and the percentage is still growing.
Ransomware has often crippled companies, hospitals, police departments, and even entire cities. Most ransomware programs are Trojans, which means they must be spread through social engineering of some sort. By watching the user for a few hours before setting off the encryption routine, the malware admin can figure out exactly how much ransom the victim can afford and also be sure to delete or encrypt other supposedly safe backups.
Ransomware can be prevented just like every other type of malware program, but once executed, it can be hard to reverse the damage without a good, validated backup. According to some studies, about a quarter of the victims pay the ransom, and of those, about 30 percent still do not get their files unlocked. Either way, unlocking the encrypted files, if even possible, takes particular tools, decryption keys and more than a bit of luck. The best advice is to make sure you have a good, offline backup of all critical files.
Traditional malware travels and infects new systems using the file system. The end result is that fileless attacks are harder to detect and stop. If you're lucky, the only malware program you've come in contact with is adware , which attempts to expose the compromised end-user to unwanted, potentially malicious advertising. A common adware program might redirect a user's browser searches to look-alike web pages that contain other product promotions.
For example, a cybercriminal might pay to place an ad on a legitimate website. When a user clicks on the ad, code in the ad either redirects them to a malicious website or installs malware on their computer. Cybercriminals have also been known to compromise legitimate ad networks that deliver ads to many websites. The goal of cybercriminals who use malvertising is to make money, of course. Spyware is most often used by people who want to check on the computer activities of loved ones.
Of course, in targeted attacks, criminals can use spyware to log the keystrokes of victims and gain access to passwords or intellectual property. Adware and spyware programs are usually the easiest to remove, often because they aren't nearly as nefarious in their intentions as other types of malware.
Find the malicious executable and prevent it from being executed — you're done. A much bigger concern than the actual adware or spyware is the mechanism it used to exploit the computer or user, be it social engineering, unpatched software, or a dozen other root exploit causes.
Unfortunately, finding and removing individual malware program components can be a fool's errand. It's easy to get it wrong and miss a component. Plus, you don't know whether the malware program has modified the system in such a way that it will be impossible to make it completely trustworthy again. Unless you're well trained in malware removal and forensics, back up the data if needed , format the drive, and reinstall the programs and data when you find malware on a computer.
Patch it well and make sure end-users know what they did wrong. That way, you get a trustworthy computer platform and move ahead in the fight without any lingering risks or questions. An security columnist since , Roger Grimes holds more than 40 computer certifications and has authored ten books on computer security. Here are the latest Insider stories. More Insider Sign Out.
Sign In Register. Sign Out Sign In Register. Latest Insider. Check out the latest Insider stories here. More from the IDG Network. A history of ransomware: The motives and methods behind these evolving attacks. TrickBot explained: A multi-purpose crimeware tool that haunted businesses for Today's top stories 12 security career-killers and how to Oldsmar cyberattack raises importance SolarWinds attack explained: And why it The state of the dark web: Insights How and why deepfake videos work — and What is the dark web?
How to access it The 15 biggest data breaches of the What is the Tor Browser? And how it can Show More. Viruses A computer virus is what most of the media and regular end-users call every malware program reported in the news. Worms Worms have been around even longer than computer viruses, all the way back to mainframe days.
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9 types of malware and how to recognize them
A computer virus is a malicious program that self-replicates by copying itself to another program. In other words, the computer virus spreads by itself into other executable code or documents. The purpose of creating a computer virus is to infect vulnerable systems, gain admin control and steal user sensitive data. Hackers design computer viruses with malicious intent and prey on online users by tricking them. One of the ideal methods by which viruses spread is through emails — opening the attachment in the email, visiting an infected website, clicking on an executable file, or viewing an infected advertisement can cause the virus to spread to your system. Besides that, infections also spread while connecting with already infected removable storage devices, such as USB drives.
The purpose of this paper is to discuss various types of computer viruses, along with their characteristics, working, effects on the computer systems and to suggest measures for detecting the virus infection in a computer system and to elaborate means of prevention. The author undertook an extensive study and review of the literature available online and on relevant web sites on the present topic. A large number of viruses were found during the study, which are causing serious damages to computer systems. The author suggests ways to detect and prevent the different computer viruses. The research is based on and limited to the study of the relevant literature available on different relevant web sites.
PDF | Purpose – The purpose of this paper is to discuss various types of computer viruses, along with used to refer to other types of malware.
What is a computer virus?
Everyone talks about computer viruses. There are regular warnings about PC viruses that can silently spread to your computer and cause great damage. But what exactly is a computer virus? What are the chances of eliminating one? And what kind of protection is really effective against them?
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