Do You Know How To Scan Zip Files For Viruses And Zip Bombs?

One of the most popular questions among consumers regarding cybersecurity for their devices is whether or not their chosen antivirus can scan zip files for viruses. However, before answering this question we should first take a brief look at what zip files actually are. Simply put, zip files (also known as ‘archive files’), are files that have been compressed to reduce storage space. This compressed file format can be used to store and transmit multiple files or folders.

Zip files are identified by their ‘.zip’ file extension and are easily created on your desktop. Once a .zip file has been created, accessing the files within requires first ‘unzipping’ or extracting them. As well as being useful for file encryption, and for creating different kinds of archives, zip files are also favored by cyber criminals, who use .zip files to send malicious files.

Can A Zip File Be A Virus?

Are zip files safe, or can zip files have viruses? As zip file viruses are popular vectors for malware authors, zip files can indeed potentially contain a virus or other malware. Cyber criminals can use zip files to distribute their malicious software because they can pack multiple files together into a single file and make it easier to distribute.

It's important to be cautious when opening zip files, especially if you receive them from an unknown source. You should always scan zip files for viruses before opening them, and install up-to-date antivirus software on your computer to ensure that it can detect and remove the latest viruses and malware. It's also a good idea to avoid downloading and opening zip files from suspicious websites or emails, and to only download files from reputable sources.

Can Antivirus Software Scan Zip Files For Viruses?

Fortunately, antivirus software can and does scan .zip files, but how the scan is performed depends on the antivirus software. Some antivirus software can scan and detect viruses that are inside the archived file. They do this by temporarily decompressing the archived files and scanning the contents, looking for any suspicious files or code that may pose a threat. The antivirus software then checks the file against its virus database to determine if it is infected with a known virus or malware.

Other antiviruses scan the files for viruses once they’ve been extracted, which is also a perfectly safe method of scanning since the antivirus will still clean, quarantine or delete (depending upon the chosen method) any infected files before they can infect your system or other files.

An antivirus software’s ability to scan archived files also depends on the format of the archived files. Sometimes, the antivirus software can only detect a virus in a .zip file, but it can’t take any further steps to remove or delete it. When this happens, you will usually have to run the antivirus directly on the infected file after you’ve extracted it.

How To Scan A Zip File for Viruses

It is important to scan zip files for viruses to prevent your computer from getting infected with malware that can cause damage to your files and steal sensitive information. If you are looking to scan zip files for viruses, you can follow these steps:

  • First, install antivirus software on your device, such as RAV Endpoint Protection.
  • Next, extract the contents of the zip file to a temporary folder on your computer. You can do this by right-clicking on the zip file and selecting "Extract Here," or by using file archiving software such as WinZip.
  • Right-click on the folder containing the extracted files and select "Scan with [name of your antivirus software]" from the context menu. This will initiate a scan of all the files in the folder.
  • Wait for the antivirus software to complete the scan of all the files in the folder. This may take a few minutes, depending on the size of the files and the speed of your computer.
  • Once the scan is complete, review the scan results to see if any viruses or malware were detected. If the antivirus software detects any viruses or malware, follow the instructions provided by the software to remove them.
  • After the scan is complete, delete the temporary folder and its contents to ensure that the virus or malware does not infect your computer.

And Then There Are Zip Bombs …

What is a zip bomb? Also known as a ‘decompression bomb’ or ‘zip of death’, zip bombs work differently from other viruses that are delivered by .zip files. Although a zip bomb is usually a small file, designed for ease of transport and to avoid suspicion, when the file is uncompressed its contents exceed far more than the system can handle. They are crafted in such a way that an enormous amount of time, space, and system memory is required to unpack them.

Unpacking them thus makes it harder for other programs to operate, including antivirus software, which are the main targets of these zip bombs.

What Does A Zip Bomb Do To A Computer?

Essentially, zip bombs are designed to exhaust your system’s resources so that it crashes and your antivirus software is disabled, which then creates an opening for other types of malware.

One notorious example of a zip bomb is the ‘’. The file itself is only a few kilobytes, but when it’s decompressed it takes up an astonishing 4.5 petabytes worth of disk space! It’s easy to understand, therefore, how zip bombs can crash a computer system.

Fortunately, antivirus software can detect zip bombs too. It does this by looking for overlapping files and by knowing not to unpack layer after layer of recursive data - a sure sign of a zip bomb.

How To Get Rid Of A Decompression Bomb Virus

If you have been alerted that the zip files on your device may contain a decompression zip bomb virus, you will need to remove it before it does any damage, by following these steps:

  • Restart your computer in Safe Mode: Restart your computer and press F8 repeatedly until you see the Advanced Boot Options screen. Select "Safe Mode with Networking" and press Enter.
  • Run an antivirus scan: Update your antivirus software and run a full system scan. This should detect and remove the decompression bomb virus from your system.
  • Delete suspicious files: Look for any suspicious files that are taking up too much space on your computer - a major clue that there is a decompression bomb virus is excessively large files. If you find any suspicious files, delete them.
  • Clear temporary files: Delete all temporary files from your computer by opening the Run dialog box (press Windows key + R). Type "temp" and press Enter. Select all the files and delete them.
  • Increase your system resources: If your computer is still slow after removing the virus, you may need to increase your system resources. You can do this by adding more RAM or upgrading your hard drive.

Are RAR Files Safe?

Another type of compressed file to watch out for is the RAR file, recognized by the .rar file extension. A RAR file is used to store and compress large files or multiple files into a single archive. RAR files are especially useful when transferring or storing large files, as they can significantly reduce the file size and make it easier to send or store. Like zip files, RAR files can be password-protected, allowing you to keep the contents of the archive secure.

But are RAR files safe? In and of themselves, RAR files are safe and do not pose a threat to your computer. However, like any other type of file, a RAR file can contain malware or viruses if it has been intentionally or unintentionally infected. Some cybercriminals may use RAR files to hide malware or viruses to evade detection by antivirus software. This can make it more difficult to detect and remove the threat, which is why it is essential to exercise caution when downloading or opening RAR files.

As with zip files, it is important to only download RAR files from trusted sources and to have a reliable antivirus software installed on your computer to detect and remove any malware that may be contained within the file. Overall, RAR files are generally safe as long as they come from a trusted source and are scanned for viruses before opening.

Protect Your Device

By taking simple pre-emptive precautions, consumers can prevent infected RAR files and zip archive files from infecting their computers. Utilizing next-generation antivirus software such as RAV Endpoint Protection is the first step. By scanning files, you will be alerted if there is any suspicious activity. It’s also advised to exert caution when downloading files from the internet, keep your antivirus software regularly updated and avoid browsing suspicious websites.

For more information on RAV Endpoint Protection and other cybersecurity products from ReasonLabs, visit: