Can a PDF file contain a virus?

I am getting tons of pdf files in email. I want to know that does pdf file can contain a virus. Some of the files that I had received are unknown. That means I cannot locate the sender. I have a antivirus, but I am not sure whether it scans the file or not. A number of documents that I receive contains PO. I cannot ignore any of them. I want to know that does this thing can be effected with the virus. I had noticed that from some time my system is working very slow. The files take time to load up and I had also seen some antivirus warnings in recent time.

Yes there can be a virus in a pdf file also. What is your antivirus. I am using Norton. It scans the emails before opening them and if it found then as a virus, it blocks the download. It is necessary that you must identify the sender first before opening the document. Because once your system is affected you might not able to work properly. I had received some spam mails recently in my system. They were having a pdf, doc, mp3, etc file attached. I had not opened them. My antivirus has already popped a warning while opening a txt file from mails. Even if you are downloading do not open them directly. Scan them first by right clicking on the same.

I am not using any email client. The reason is that when you click on the attachment it is already in your system and there are chances the malware is triggered. The best way is to use a web version. You can view those files directly in Google Docs if you have a Gmail account. If there is security issue those files will blocked automatically. Get a good antivirus which features a mail scanner. This will keep a watch on the attachment. It is not true that PDF file will be completely secure.

What I know as per my experience pdf files does not has virus. For a malware you need some files that can execute itself and the chain reaction begins. While in pdf there would be a scanned image document and it is read by a pdf reader. So there are less chances that a malicious code will be induced and your system might not perform well. Another thing keep your firewall on. This firewall blocks any incoming and outgoing connectivity.

Till you are working on Windows, your system is vulnerable with anything. Some years ago I had seen a news in Economic Times, which says that there is a virus induced in pdf file and it is distributed around the web. That proves that a pdf file also has virus. You must scan your system before opening the attachment.

It is right. PDF can have virus, they are used to spam system and spread virus. Sometime Auto-Preview is enabled where attachments which allows the virus to trigger on its own. There are some internal add-in that allows the attachment to view on its won.