To reduce the risk we may only accept certain file extensions, but attackers are able to encapsulate malicious code into inert file types. Testing for malicious files verifies that the application/system is able to correctly protect against attackers uploading malicious files.
Do you know that a simple task such as opening PDF files can infect your computer with malware? This is a very common method used by hackers to install malicious software on your system and gain access to it.
Adobe Reader comes with support for javscript embedded in PDF file. Hackers can simply add malicious javascript code to the PDF file to exploit this vulnerability. When you open the PDF file, the malicious javascript get executed and install malware on your computer, all without you knowing it.
Many people don’t pay enough attention to the fact that PDF files can contain viruses and open them without scanning them. Recently, Microsoft Malware Protection Center released a list of commonly infected PDF files that have been detected over the past few months.
Download Malicious Files
Here is the list of files that has been released:
pdf_new[1].pdf
auhtjseubpazbo5[1].pdf
avjudtcobzimxnj2[1].pdf
pricelist[1].pdf
couple_saying_lucky[1].pdf
5661f[1].pdf 7927
9fbe0[1].pdf 7065
pdf_old[1].pdf
The question that remains here is how can you protect yourself from getting infected through this method? The answer to this question is pretty simple. As most of the PDF exploits the vulnerabilities using JavaScript, one way to protect your system would be to disable JavaScript on your PDF reader.
How to Disable JavaScript in Adobe Reader?
Open Adobe Reader and go to “Edit -> Preferences” or simply press “CTRL + K”.
From the sidebar, select JavaScript and uncheck “Enable Acrobat JavaScript”.
Other Ways to Protect Yourself
First you need to ensure that you never open an email or download anything that is sent to you by an unknown person/source. It is recommended that you always check the name of the file in the email before opening it on your computer or web browser. If you use Gmail, it scans every attachment that is delivered to your Inbox and blocks the infected file if it’s already in your Inbox. Although opening an email is safe, it is still recommended that you avoid opening emails that have attachments or links from unknown senders.
Second, ensure that you update your Windows and your antivirus program. It is very important to perform a regular system scan to check if your computer is infected or not. If you are not sure of the PDF files that you have downloaded, you can scan them with Virustotal to make sure they are virus-free .
Final Words
As hackers are finding new ways to attack you, you should take all the precautionary steps to make sure your system does not get infected. On the other hand, the antivirus companies are also on the verge of releasing new virus definitions every day. So, it is highly recommended that you install good antivirus software such as Kaspersky or BitDefender, and set them to update definitions automatically. You can also try Microsoft Security Essentials which is available free of charge and can provide decent security. You can also take a look at some tips to protect yourself from viruses and malware.
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