These Types of Files Are Often Used to Hide Viruses

Have you ever encountered a file that seems potentially dubious? A PDF file may have been attached to an email, and you were uncertain about its security.

Executable (EXE) Files

An EXE file is a sort of executable file predominantly utilized in the Windows operating system. Opening this type of file initiates the execution of a computer program on your device, whether it be the software itself or an installation package. The Chrome browser is an executable file (EXE). Double-clicking the icon initiates the execution of the code that operates Chrome, so launching the browser.

Similarly, double-clicking any executable file will initiate the execution of its code. An untainted EXE will do its designated function, whereas a malicious EXE will deploy malware onto your system, masquerading as an innocuous program. Not all EXE files are viruses; however, it is prudent to examine and verify them before to execution, and one should refrain from clicking on arbitrary EXE files.

One issue is that malware makers are aware that you may refrain from clicking on an arbitrary executable file. Consequently, they obfuscate harmful EXE programs by employing alternative file extensions, such as those listed below.

Compressed Files: ZIP/RAR

A ZIP or RAR file resembles a directory that encompasses several files. Upon extraction, you may encounter many file kinds, including scripts, executables, and others, contingent upon the contents of the archive.

Consider a website template for the purposes of this essay. Certain templates are extensive, encompassing HTML, CSS, JavaScript, media content (images/videos), and more elements. These templates are optimally disseminated through compression formats, such as ZIP or RAR, to minimize file size. However, when you extract the files, any dangerous content is also extracted alongside them.

While I am not asserting that a virus is definitively present, compressed file archives are a common medium for malware dissemination, poised for activation.

Microsoft Application Files

Excel, PowerPoint, and Microsoft Word files are infamous for harboring viruses and harmful scripts. These tools enable users to generate "macros," scripts that facilitate task automation. These programs has the capability to damage your system.

Like PDFs, a Word document (or other Office 365 applications) may have embedded code. The code may be innocuous; nonetheless, there remains a possibility that you download an arbitrary DOCX file, open it, and receive a warning from your antivirus software regarding potential threats. Nearly all Office 365 file extensions, such as DOC, DOCX, XLS, and XLSX, may harbor malware. Alternatively, the virus is directly masquerading as an Office 365 file, although it is, in fact, an executable poised to install malicious software on your PC.

The aforementioned five file types are well recognized as potential carriers of viruses. Nevertheless, virtually any file format may have malicious functionality; harmful image files such as JPGs, PNGs, and GIFs present a comparable concern. Exercise prudence before downloading or opening unfamiliar files to protect yourself. If an unfamiliar EXE file arrives on your desktop, it is likely malicious; refrain from clicking it (albeit you may have more significant issues to address)! Your intellect and discernment constitute your primary line of defense.

PDF files

The likelihood of possessing a PDF file on your computer is substantial, as PDF files are ubiquitous. They serve as substitutes for physical books, facilitating the storage of essential business information and additional content. Considering their utilization, it is unsurprising that they present a significant attack vector for deploying a virus.

Typically, PDF files are secure, although they may include embedded code. Moreover, the PDF reader may harbor a zero-day exploit, presenting an additional danger. It is advisable to refrain from downloading arbitrary PDF files from the internet.

Script Files

Script files utilize file extensions such as JS, PY, SH, and others. Independently, they are incapable of accomplishing anything. They must be executed in their designated contexts. A .js file requires a JavaScript runtime, primarily a web browser.

The risk of a potential virus being executed from one of these files originates from the user, as interaction with the file is necessary for the code to operate. Upon accessing your browser's developer tools on Facebook, you will get a warning message:

Similarly, .py and .sh scripts must be executed by a user. Executing these files on your computer without understanding their functions may result in adverse consequences.