Malwares Malicious Software (original) (raw)

Last Updated : 12 Jul, 2025

**Malware is malicious software and refers to any software that is designed to cause harm to computer systems, networks, or users. Malware can take many forms. Individuals and organizations need to be aware of the different types of malware and take steps to protect their systems, such as using antivirus software, keeping software and systems up-to-date, and being cautious when opening email attachments or downloading software from the internet.

What is Malware?

Malware is software that gets into the system without user consent to steal the user's private and confidential data, including bank details and passwords. They also generate annoying pop-up ads and make changes in system settings They get into the system through various means:

• Along with free downloads.
• Clicking on a suspicious link.
• Opening emails from malicious sources.
• Visiting malicious websites.
• Not installing an updated version of antivirus in the system.

**Types of Malware

**1. Virus

Computer virus refers to a program which damages computer systems and/or destroys or erases data files. 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.

**Symptoms of Virus

• Letter looks like they are falling to the bottom of the screen.
• The computer system becomes slow.
• The size of available free memory reduces.
• The hard disk runs out of space.
• The computer does not boot.

**Types of Computer Virus

• **Parasitic - These are the executable (.COM or .EXE execution starts at first instruction). Propagated by attaching itself to particular file or program. Generally resides at the start or at the end of a file, e.g. Jerusalem.
• **Boot Sector - Spread with infected floppy or pen drives used to boot the computers. During system boot, boot sector virus is loaded into main memory and destroys data stored in hard disk, e.g. Polyboot, Disk killer, Stone, AntiEXE.
• **Polymorphic - Changes itself with each infection and creates multiple copies. Multipartite: use more than one propagation method. >Difficult for antivirus to detect, e.g. Involutionary, Cascade, Evil, Virus 101., Stimulate. Three major parts: Encrypted virus body, Decryption routine varies from infection to infection, and Mutation engine.
• **Memory Resident - Installs code in the computer memory. Gets activated for Operating System run and damages all files opened at that time, e.g. Randex, CMJ, Meve.
• **Stealth - Hides its path after infection. It modifies itself hence difficult to detect and masks the size of infected file, e.g. Frodo, Joshi, Whale.
• **Macro - Associated with application software like word and excel. When opening the infected document, macro virus is loaded into main memory and destroys the data stored in hard disk. As attached with documents; spreads with those infected documents only, e.g. DMV, Melissa, A, Relax, Nuclear, Word Concept.
• **Hybrids - Features of various viruses are combined, e.g. Happy99 (Email virus).

**2. Worm

A worm is a destructive program that fills a computer system with self-replicating information, clogging the system so that its operations are slowed down or stopped.

**Types of Worm

• **Email worm - Attaching to fake email messages.
• **Instant messaging worm - Via instant messaging applications using loopholes in network.
• **Internet worm - Scans systems using OS services.
• **Internet Relay Chat (IRC) worm - Transfers infected files to web sites.
• **Payloads - Delete or encrypt file, install backdoor, creating zombie etc.
• **Worms with good intent - Downloads application patches.

**3. Logical Bomb

A logical bomb is a destructive program that performs an activity when a certain action has occurred. These are hidden in programming code. Executes only when a specific condition is met, e.g. Jerusalem.

**4. Trojan / Backdoor

Trojan Horse is a destructive program. It usually pretends as computer games or application software. If executed, the computer system will be damaged. Trojan Horse usually comes with monitoring tools and key loggers. These are active only when specific events are alive. These are hidden with packers, crypters and wrappers.< Hence, difficult to detect through antivirus. These can use manual removal or firewall precaution.

**5. RootKits

• Rootkit is a collection of tools that allow an attacker to take control of a system.
• Can be used to hide evidence of an attacker’s presence and give them backdoor access.
• Can contain log cleaners to remove traces of attacker.
• Can be divided as: - Application or file rootkits: replaces binaries in Linux system - Kernel: targets kernel of OS and is known as a loadable kernel module (LKM)
• Gains control of infected m/c by: - DLL injection: by injecting malicious DLL (dynamic link library) - Direct kernel object manipulation: modify kernel structures and directly target trusted part of OS - Hooking: changing applicant's execution flow

**6. Advanced Persistent Threat

Created by well funded, organized groups, nation-state actors, etc. Desire to compromise government and commercial entities, e.g. Flame: used for reconnaissance and information gathering of system.

**7. Spyware and Adware

Normally gets installed along with free software downloads. Spies on the end-user, attempts to redirect the user to specific sites. Main tasks: Behavioral surveillance and advertising with pop up ads Slows down the system.

How To Know if a Device is Infected With Malware?

• Performing poorly on the computer by execution.
• When your web browser directs you to a website you didn't intend to visit, this is known as a browser redirect.
• Warnings about infections are frequently accompanied by offers to buy a product to treat them.
• Having trouble starting or shutting down your computer.
• Persistent pop-up ads.

How To Protect From Malware?

• Update your operating system and software. **Install updates as soon as they become available because cybercriminals search for vulnerabilities in out-of-date or outdated software.
• Never click on **a popup's link. Simply click the "X" in the message's upper corner to close it and leave the page that generated it.
• Do not click on unidentified links. If a link seems suspicious, avoid clicking it whether it comes from an email, social networking site, or text message.
• Choose the websites you visit wisely. Use a **safe search plug-in and try to stick to well-known and reputable websites to avoid any that might be malicious without your knowledge.
• Emails requesting personal information should be avoided. **Do not click a link in an email that appears to be from your bank and asks you to do so in order to access your account or reset your password. Log in immediately at your online banking website.

How To Remove Malware?

A large number of security software programs are made to both find and stop malware as well as to eliminate it from infected systems. An antimalware tool that handles malware detection and removal is Malwarebytes. Malware can be eliminated from Windows, macOS, Android, and iOS operating systems. A user's registry files, currently running programs, hard drives, and individual files can all be scanned by Malwarebytes. Malware can then be quarantined and removed if it is found. Users cannot, however, set automatic scanning schedules like they can with some other tools.

• Malwarebytes
• SUPERAntiSpyware
• Malicious Software Removal Tool (MSRT)
• Bitdefender Antivirus Free Edition
• Adaware Antivirus Free
• Avast Free Mac Security

Advantages of Detecting and Removing Malware

• **Improved Security: By detecting and removing malware, individuals, and organizations can improve the security of their systems and reduce the risk of future infections.
• **Prevent Data Loss: Malware can cause data loss, and by removing it, individuals and organizations can protect their important files and information.
• **Protect Reputation: Malware can cause harm to a company's reputation, and by detecting and removing it, individuals and organizations can protect their image and brand.
• **Increased Productivity: Malware can slow down systems and make them less efficient, and by removing it, individuals and organizations can increase the productivity of their systems and employees.

Disadvantages of Detecting and Removing Malware

• **Time-Consuming: The process of detecting and removing malware can be time-consuming and require specialized tools and expertise.
• **Cost: Antivirus software and other tools required to detect and remove malware can be expensive for individuals and organizations.
• **False Positives: Malware detection and removal tools can sometimes result in false positives, causing unnecessary alarm and inconvenience.
• **Difficulty: Malware is constantly evolving, and the process of detecting and removing it can be challenging and require specialized knowledge and expertise.
• **Risk of Data Loss: Some malware removal tools can cause unintended harm, resulting in data loss or system instability.

Conclusion

In conclusion, malware include significant risks to both individuals and organizations, requiring proactive measures for protection and removal. Utilizing a combination of antivirus and anti-malware tools with software updates can effectively protect systems. While detecting and removing malware can be time-consuming and costly, the benefits of enhanced security, data protection, and increased productivity.