I have seen this happen as part of educating people about computer security is to think before you click. Here, it is about being careful about responding to emails and Websites of doubtful provenance so you don’t become a victim of a scam or find your computer full of malware.
For example, phishing scams initially used links in the email as a hook to get people to “verify” their accounts or take similar action. But they are now using “loaded” attachments with the copy of the email not having any links or HTML to avoid being rejected by security tools that are part of email clients or the populace not taking to the bait due to the public education about phishing scams. The hook in these situations are the attachments that are crafted to take advantage of weaknesses in the software or carry links to Web resources as mentioned below.
PDF files represent their own dangers because they can either be crafted maliciously or contain links to Web resources. This is compounded by the problem that not all PDF reader software handles Web links in a manner similar to a Web browser. For example, a lot of these programs don’t show the URL when you hover over or dwell on the link before you click.
I would personally like to see PDF and similar document viewers support the ability to link with “website-reputation” engines like what Symantec and other security-software vendors offer and show graphics that indicate if a link you are hovering on is safe or not. Similarly, search engines, website reputation agents, security scanners and similar tools could also examine PDF files for abnormal construction and questionable links.
Instead, we have to do a “reality check” regarding these emails. For example, are the emails from a company whom you have had business with or part of ongoing business with that company? Are you expecting an email to come through with attachments? Do they contain a lot of poor spelling or grammar or aren’t commensurate to the language they are meant to be written in? Do they reflect the tone of what the business and its industry is about? Simply, does the context sound too “out of this world” to be real?
This also applies to any offers provided through instant-messaging or social-network channels including the Facebook “fake-event” scams that are popping up as I have mentioned before.
But for the moment, are you sure that the link or attachment you are to click on is kosher before you click on it?