You've been warned that the Internet is something of a security minefield--that it's easy to get in trouble. You can do everything you can think of to protect yourself and still be taken by a malware infection, a phishing scam, or an invasion of on??line privacy. We'd like to provide a little help. Here are some of the hazards you may encounter, how dangerous they are, and what you can do to stay out of harm's way.

Threat 1: 'Poisoned' search engine results that go to malware-carrying Websites

The Place: Search engines
Search engine poisoning is the practice of building tainted sites or pages that are designed to rank high in a search on a given topic. For example, according to a recent study by the security firm McAfee, 19 percent of search results for "Cameron Diaz and screensavers" had some sort of malicious payload. Breaking news topics and Facebook are also common search targets for attackers.

If You Have to Go There: Pick and choose which sites to go to. Don't just blindly click search results; check each URL first to make sure that it really leads to the site you want. Although any site can be hacked, visiting the Washington Post's story on a hot news topic, for example, is probably a wiser choice than following a link to a site you've never heard of before.

Threat 2 : Malicious PDFs that try to fool you into installing malware

The Place: Hacked Websites, plus your inbox
As Microsoft has become more serious about Windows security over the past few years, would-be attackers have had to find new ways to infect PCs. Attacking flaws in Adobe Acrobat is one of these newer methods. So-called poisoned PDFs are PDF files that have been crafted in such a manner that they trigger bugs in Adobe Reader and Adobe Acrobat; posted on a hijacked Website, they may let an attacker commandeer your PC and access your files and personal info.
Feeling particularly paranoid? Uncheck 'Allow opening of non-PDF file attachments with external applications' (near the top) to head off certain PDF exploits.A newer variant takes an otherwise innocent-looking PDF document and inserts malware into it. Adobe Reader may pop up an alert asking if you want to run the malware, but hackers can edit those messages to trick you into opening the file.
How serious is this problem? In 2009, attacks using malicious PDFs made up 49 percent of Web-based attacks, according to security firm Symantec.

If You Have to Go There: First, always make sure that you're running the latest version of Adobe Reader.
You can also use a different PDF reader, such as Foxit Reader. This can protect you from attacks on holes in Adobe Reader itself, but it won't make you immune to all PDF attacks, such as the newer ones that embed malware inside the PDFs. Make sure, also, that you update to Adobe Reader 9.3.3 or later (Reader 8 users should update to version 8.3.3 or later); these updates change the way Adobe Reader handles non-PDF attachments and reduce the risk from such attacks.
You can turn off Adobe Reader's ability to open non-PDF attachments by going to Preferences, clicking Trust Manager, and unchecking Allow opening of non-PDF file attachments with external applications.
The next major release of Acrobat and Reader will provide a new "protected mode" against these attacks.

Threat 3 : Drive-by downloads that install malware when you visit a site

The Place: Hacked legitimate sites
A drive-by download occurs when a file downloads and/or installs to your PC without you realizing it. Such downloads can happen just about anywhere. Some sites are built to lure people into a drive-by download; but in a common attack method, criminals will hack a Web page, often on an otherwise legitimate site, and insert code that will download malware to your computer.

If You Have to Go There: The first thing to do is to keep your security software up-to-date, and to run regular malware scans. Many security suites can flag suspicious downloads.

Threat 4 : Sites that lure you in, get you to sign up, then sell your e-mail address for spam

The Place: 'Free electronics' sites
You've no doubt seen sites around the Web blaring, Get a free iPad! Get a free notebook! A free iPod! It's easy! These sites aren't typically dangerous in the classical sense--you probably won't get infected with malware--but your personal information could be sold to other businesses, who can then use it to sell more stuff to you.

If You Have to Go There: Read the privacy policies. And then read them again. Also, beware of privacy policy loopholes--even though a site says that it won't sell your private data to third parties, depending on the language of the policy, they may still be able to give your information to "affiliates."

Threat 5 : Malicious video files using flaws in player software to hijack PCs

The Place: Video download sites
Attackers have been known to exploit flaws in video players such as QuickTime Player and use them to attack PCs. The threats are often "malformed" video files that, like malicious PDFs, trigger bugs in the player software that let the attackers in to spy on you, plant other malware, and more.

If You Have to Go There:Keep your player software up-to-date. Apple and Microsoft periodically release patches for QuickTime and Windows Media Player, respectively. Avoid downloading videos at random. Stick to well-known video sites such as YouTube, or to download services like iTunes.If you want to play dvd videos on ipad , choose a clean and safe video to ipad converter software like professional dvd to ipad software.