Category: 2. Computer Virus

There are many warning signs or symptoms which show that a computer is infected with a virus, some of which are as follows:

• Slow computer performance: The machine may work slowly, e.g., it will take more time to open or shut down the computer or while opening a file, document, computer application, etc. The operating system and internet speed may get slow.
• Frequent pop-ups: A virus may cause unusual frequent pop-ups on your window.
• Hard Drive issue: The hard drive may exhibit unusual high activity even when it is not in use. It may cause unwanted changes to your hard drive and may freeze or crash this device.
• Frequent crashes: One may experience frequent sudden system crashes while playing games, watching videos, or doing some other work using the infected system. A blue screen appears when it crashes.
• Unknown programs: Unwanted programs may open or start automatically when you start your computer. You can see these programs in your computer’s list of active applications. Sometimes, the window shuts down unexpectedly without any reason.
• Unusual activities: Your machine may perform differently, such as you may not be able to log into your accounts, to delete the corrupt files, and Blue Screen of Death (BSOD) may appear frequently, and more. Furthermore, the hardware, software, or OS may start malfunctioning leading to crashing the system abruptly.
• Impaired security solutions: Sometimes, security measures taken by you, such as antivirus may not work smoothly due to virus attack on your computer.
• Network issue: Sometimes, you experience high network activity even if you are not connected to the internet and vice versa.
• Unnecessary advertisement: We often see advertisements while browsing, but if you see them even when you are not browsing, it may indicate a virus on your computer.
• Display problems: You may experience different colors in your display if your computer is affected by a virus.
• Affected Applications: Some viruses are developed to affect specific applications. Consequently, some applications may not work on your computer if it is infected.
• Blocked by Antivirus Sites: An antivirus site may deny access to a computer that is infected by a virus.
• Dialog Boxes: Many dialog boxes keep appearing suddenly on your screen.
• Printer Issues: A printer attached to an infected computer may print documents without getting any command or in an inappropriate manner.
• Changed Homepage: Your home page may get changed without any effort from your side. For example, you may see a new toolbar on your screen, and you may be redirected to a different web address instead of the page visited by you initially.
• Strange messages: One may see strange messages on a computer screen such as error messages, e.g., “cannot rename “folder” as a folder already exists with this name”

It is a hidden computer virus, which specifically attacks operating system processes. It usually hides itself in partitions, files or boot sectors and is capable of going unnoticed during antivirus or anti-malware scans, i.e., it can avoid detection intentionally.

It is also known as wabbit, a fork bomb. It is capable of creating new processes, and each of the new process further creates new processes. This process continues until this virus utilizes all the available resources in the system and system falls short of resources. It may cause the target system to slow down and crash. For example, it is like an Infinite loop that repeatedly creates processes that consume lots of CPU cycles and operating system resources.

It creates its thousands of copies itself; in each copy, it changes the sequence and byte values to evade detection by antivirus software. Even the best antiviruses may not be able to detect this virus. Polymorphic viruses affect data types and functions and generally spread through spam, infected sites, and while using other malware.

It is a non-resident computer virus, which resides in an executable file. Whenever the infected file is executed, it infects the other files.

It encrypts its payload to make its detection more difficult. It comprises two parts: an encrypted virus body and a decryptor, which decrypts the virus when it is executed. After decryption, the virus can execute itself in order to replicate and become a resident. Furthermore, it is different from cryptolocker, which is a computer virus that encrypts the hard drive data and holds it for ransom.

It resides itself in a file whose name is similar to another program file, which is executed normally. When the program file is executed, the virus gets activated and performs malicious steps such as deleting the files on your computer hard drive. Globe virus is a first known companion virus, which was found in 1992.

It infects the CMOS, which stands for complementary metal-oxide semiconductor and is a memory chip that contains the system configuration. This virus can erase or reset the system configuration.

It is also known as a spacefiller virus. As the name suggests, this virus tends to install itself by occupying the empty sections of a file. It is not easy to detect this virus as it fills the empty spaces without changing the size of the file.

Trojan horse is a malware like a virus or a worm, but it is technically different from both. It can’t replicate like virus and worm. Trojan horse hides itself in a program. Once you install any such program, the trojan horse enters into your computer. It can provide unauthorized access to your computer, send your files to other computers, and may delete files or can make other unwanted changes in your computer.