A stealth virus is a kind of malware that does everything to avoid detection by antivirus or antimalware. It can hide in legitimate files, boot sectors, and partitions without alerting the system or user about its presence. Once inside a computer, a stealth virus allows an attacker to take over the functions of the infected computer.
In other words it actively hides itself from antivirus software by either masking the size of the file that it hides in or temporarily removing itself from the infected file and placing a copy of itself in another location on the drive, replacing the infected file with an uninfected one that it has stored on the hard drive.
These virus can reside anywhere in the system like files, partitions and boot sectors without any indications of their existence. Like other viruses, a stealth viruses can take control of many parts of one’s PC.
First Disk Operating System (DOS) virus Brain is a stealth virus? Brain was discovered way back in January 1986. It is classified as a system infector. It monitors a computer’s physical disks. Every time an attempt is made to discover it, Brain points the system to read an uninfected boot sector instead. It’s much like throwing a stone to make a sound somewhere else so a person looking for you won’t discover your hiding place.
How Computer Stealth Virus Infect
Computer viruses have been plaguing individuals, organizations and government agencies for the past 40 years. Evolving over time, these viruses have kept pace with the newest advances in technology, much to the consternation of information technicians who work to keep networks and systems safe. With a rise in technological advances, society increasingly becomes at risk for hackers or other forms of cyber-attacks. Identifying how computer viruses have grown over time helps the unsung heroes of systems information keep our data safe.
Mathematician John von Neumann first theorized the concept of a computer virus in the late 1940s and published an article on his theory in 1966. His vision of a virus was as a self-replicating automatic entity and in 1971 the Creeper Virus, the first real computer virus, was exactly that.Then more different type of viruses were developed and stealth virus is one of them.
A stealth virus can infect a computer system in a number of ways, like :
1.A stealth boot sector virus might overwrite systems master boot record with malicious code and modify the operating system’s log of any file modification tracks.
2.The stealth viruses can also avoid detection by concealing the size of the file it has infected as some heuristic based anti-virus detection techniques use the difference in size as a parameter of identifying infected files.
Stealth virus are very difficult to detect due to their inherent nature of replacing themselves with genuine files/processes/codes and removing all tracks.
A stealth virus that has successfully infiltrated a computer can only be detected after a disk boot. You can do that by starting your system from a removable disk such as a universal serial bus (USB) drive set to be read before the computer’s hard drive. That way, even if the virus has complete control over the system, it can’t run before your antivirus or antimalware.
Once detected, remove the virus, including its copies, from your computer. This process is complicated, so you may need an expert’s help. That said, the best way to avoid stealth viruses is to prevent them from infecting your system with the help of advanced security software that’s always updated.
It is also best to adhere to security best practices, such as never opening spam and clicking suspicious links.