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By using our site, you agree to our cookie policy. Cookie Settings. Learn why people trust wikiHow. Download Article Explore this Article Steps. Tips and Warnings. Related Articles. Assess what you're downloading. Are you downloading pornography or a warez cracked program? Or are you downloading an add-on to help improve your Mozilla Firefox experience?
There's a much greater chance that the pornography and warez software is going to contain a virus hidden in the download. What's the file? That's your first clue. If it is illegal or suspicious looking, it's probably dangerous. Look over the site. It may seem superficial, but if you're downloading a file from a very basic site there's a higher chance that the site will have a virus hidden in its downloadable files than from a site that looks like it's been made from years of dedicated web designers.
Consider who you are downloading the file from. Think about it logically, if you're downloading something from Microsoft, it's not likely that you're downloading a virus. Please type a Name. I want more news and awesome tips. Our Reviews WizCase includes reviews written by our experts. Referral fees Wizcase may earn an affiliate commission when a purchase is made using our links. Meanwhile, using PDF instead means everyone can read it without a problem.
This means the PDF format can adapt to different devices and machines, too. Not only can people from any operating system or device download it, but a lot of web browsers these days will open the PDF within itself, allowing you to read the document without even downloading it. Saving it as a PDF, however, keeps all the elements of the website intact with zero hassle.
First, in order to save files as PDF, we need to take a strange detour. Yes, this is the same feature you use to print documents via a printer! It may seem unusual to use the print feature, but it has its benefits. Mainly, if you can print a document, you can save it as a PDF, too. This means everything with a print function can be saved as a PDF, from Word documents to webpages.
Click the option to select a printer. Go ahead and select this printer, then click Print. The PDF file format has many interactive features intended to make the format more useful, but which create significant security risks, including: - The use of javascript to provide interactive content , which allows automation of the user interface - The ability to interact with the local file system - the ability to issue an HTTP request to a remote server - the ability to carry a payload of arbitrary file attachments, including malware - the ability to present a fillable form to the user, and then capture and act on the information filled in These abilities combined together make a powerful toolkit for an attacker.
Many so-called "drive-by download" attacks rely on the use of PDF files. Common PDF viewers attempt to provide safety for these features by creating sandbox environments or giving the user prompts, but these solutions are both more complex and therefore subject to their own vulnerabilities and less compatible with other parties' products than the simpler solution of simply leaving out that functionality entirely. Sumatra is one example of a PDF viewer that does not provide many of the functions which are most commonly used in PDF exploits.
By completely eliminating entire categories of potential attacks, such programs greatly reduce the risk of viewing unknown PDF files. A further advantage of using a less popular viewer is that because it's both less common and less powerful, it's a less interesting target.
The Sumatra viewer could be possibly be exploited by a specially crafted PDF which takes advantage of some unknown bug to cause a buffer overflow, for example. Such cases are rare however, and there have not been any significant security exploits for Sumatra in recent years. Use a virtual machine that can be reverted to clean slate after tests. If the PDF reader is vulnerable, your real workstation will be much less likely to be affected. Latest versions of Adobe Reader version Obviously, you'll want to close any sensitive PDFs like your bank statements before opening the untrusted one.
We can say ALL of the in-the-wild or targetted attack using malicious PDF file are covered with obfuscation techniques to hardened the analysis or detection process.
Most of the obfuscation technique are mainly using JavaScript obfuscation like eval , String. We can advise you to get the latest patched version of PDF reader with turned-off JavaScript functionality to open the file, but the good solution is to get a virtual machine where you can delete it or revert the snapshot after opening the file.
Another easy and less time consuming option is to open it in the Sandboxie app, which would isolate it. You can open the PDF in a container. I guess no one targets Okular running on FreeBSD though it can still be vulnerable , so if you open the file in a VM you should be very safe.
In order to do harm the rogue payload must match the viewer version and the OS and the CPU architecture of course. It is really low-level assembly and memory stuff the payload expects to be placed at a particular memory address and expects some standard system functions to be available. If you change any of those, then the payload may not execute properly or the viewer may simply crash without doing harm.
Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. How to safely view a malicious PDF? Some newer works are available for free, too, either from independent authors looking for publicity or known authors who agree to offer some of their older works temporarily free to help promote newer books.
Rule of thumb: If it sounds too good to be true, it is. So stick with reputable sites or your ebook reader's official store, and be sure to keep your antivirus software up to date. All rights reserved. Firefox is a trademark of Mozilla Foundation. App Store is a service mark of Apple Inc. Alexa and all related logos are trademarks of Amazon.
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