A computer virus is malicious software that secretly copies and spreads to other computers. It does this by putting itself into the boot sector of your hard disk and other programs and files. When this occurs, we say the affected areas are “infected.”
Most viruses are pathogenic, meaning they cause harm to their hosts. A virus can compromise your privacy by accessing sensitive information (such as banking details), corrupting data, stealing storage or processing capacity, monitoring your keystrokes, or spamming your contacts. However, if you’re exceptionally fortunate, it might show scatological, hilarious, or political messages.
Computer viruses can be found and removed with the help of anti-virus software. Signature scanners and heuristic detectors are the two primary categories. Heuristics are employed to uncover unknown infections, while signature scanning is used to identify existing threats.
Virus-ridden data
Historically, less than a decade ago, anti-virus software was only required to examine files with executable (or program) extensions like.exe or.com because most viruses were contained in these types of files. Microsoft Word documents and other non-executable (and presumably innocent) files are now among the many that anti-virus software must scan.
A macro is a sequence of steps that may be recorded and assigned to a specific key combination or menu item in Microsoft Word. A legal disclaimer, for instance, may be registered as a macro so that it could be used later. Simply pressing the appropriate shortcut key combination or selecting the macro’s name will insert the text into the current document (saving you the trouble of retyping the disclaimer).
Although macros can speed up some processes, they also carry some danger. Malicious coders can use them to sneak viruses into papers and then deliver those documents as email attachments to unsuspecting recipients. When victims open the wings, the malware is unleashed on their machines.
In addition to executable files, malicious code can be hidden within other files.
Viruses in email bodies can infect some email clients, including Microsoft Outlook Express and Outlook. Simply previewing or opening a mail can infect your machine.
Virus detection
Antivirus software employs signature scanning, heuristic detection, and file emulation to determine if a file contains a virus.
Fingerprint readers
Viruses are typically identified using signature-based detection. The computer’s boot record, applications, and macros are scanned for code patterns that match those of known viruses. Viruses can hide anywhere in an existing file. Thus, the entire file must be reviewed.
Anti-virus program developers store information about known virus features in dictionaries of virus signatures. Anti-virus software relies on checking files against tables of viral signatures, which must be continually updated because thousands of new viruses are developed daily.
Bad coders can make viruses that encrypt themselves or change themselves so that they don’t match the virus signatures in the dictionary, both of which help them sneak past security systems undetected.
The signature-based method is highly successful against viruses in practice. However, it cannot be utilized to detect novel or altered viruses. Heuristics are necessary to combat these dangers.
Assumption-based detectors
In heuristic detection, one uses a process of trial and error informed by one’s prior knowledge. Example virus characteristics that heuristic detectors can search for include code set to activate on a specific date.
Generic signatures are a heuristic approach that can detect new conditions of known viruses by comparing them to known malicious code and looking for minor differences. This allows for the detection of previously identified viruses that have undergone modifications.
Emulation of Files
Another heuristic method is to mimic a file’s behavior. The process entails launching a file in a sandbox, a contained environment where suspicious software may be tested without harming the rest of the system.
Anti-virus software monitors program activity and takes corrective measures to clean a computer if it detects anything dangerous.
Antivirus software that runs in memory
Antivirus software using a memory-resident installation method places programs in RAM that continue to run in the background regardless of what else is open on the computer.
Random access memory (RAM) is used by running applications, while the hard drive stores the computer’s data. Software is often loaded into RAM as its initial step when booting up. After their allotted time in RAM has passed, programs will leave. Furthermore, everything stored in RAM is lost if the power is cut off. When you turn off your computer, the programs and files on your hard disk do not disappear.
Anti-virus applications that reside in RAM keep an eye out for suspicious behavior that could indicate the presence of malware, such as the execution of a file downloaded from the internet, copying or unzipping a file, or modifying the source code. It will also monitor memory for leftovers from previously executed programs.
Memory-resident programs halt all processing when they detect malicious behavior, then prompt the user for confirmation before continuing.
Drawbacks
Antivirus software has certain downsides despite the many advantages it provides. Because it uses your computer’s resources, you may notice a slight slowdown in performance.
Currently, no anti-virus software can fully protect your computer from every possible virus. But it can make you feel too safe once it’s set up. Sometimes the software can present you with options and prompts that can be confusing. If you make the wrong choice, you could get sick.
Heuristic detection is commonly used in anti-virus programs. This needs tweaking to reduce the number of false positives or safe files being flagged as infected.
Serious issues can arise from false positives. A false positive on a critical file can render the operating system or some applications inaccessible if an antivirus program is set to delete or quarantine infected data promptly. Symantec, Norton AntiVirus, McAfee, AVG, and Microsoft are major anti-virus service providers that have experienced this for several years.
Since antivirus programs typically operate at the OS’s most secure kernel level, they also present a possible attack vector. It must do this to gain access to any files and processes that could be harmful. Anti-virus programs have been known to become infected by viruses.
Keep in mind that not all heuristic approaches can identify novel infections. This is because malicious coders ensure their new viruses are undetectable by the industry’s leading anti-virus software before releasing them into the wild.
Paul Kennedy has been writing and editing professionally for over 30 years. His portfolio includes advertising and website copy, corporate brochures, corporate magazines and newsletters, book writing and editing, newspaper articles, and managing commercial magazines and copywriting teams. Send an email to [email protected] or [email protected] to get in touch with him.
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