Did you contract a virus yesterday? No, not that kind of virus.

Most people are aware that computer viruses are legion. They know enough to avoid opening e-mail messages about wealthy Nigerians handing out free money or lost lottery winnings (just give them your bank account number and password!).

But the computer in your hand -- that iPhone, Blackberry, or Android phone -- is just as at risk, and offers a growing array of opportunities for hackers and criminals to take advantage of you.

For the first time ever, more smartphones than computers were shipped during the last quarter of 2010, according to International Data Corp. That means more than 100 million smartphones were moved during that time period (proving my earlier point that the PC is dead). Numbers like that make the devices attractive targets for hackers.

Last week computer security firm McAfee reported that malicious software or malware aimed at mobile phones increased by 46 percent from 2009 to 2010. The company said 55,000 new malware threats are emerging every day.

"It's definitely happening," said Adam Wosotowsky, the principal engineer at McAfee Labs, referring to attacks aimed at smartphones, "and it's swiftly increasing."

In fact, many apps leave users vulnerable by failing to encrypt passwords and account information. ViaForensics, which specializes in mobile security, routinely tests apps. The company recently examined several popular Android apps, including Groupon, Facebook, and Mint.com, and found that they all failed to secure important information such as user names and personal information. It found similar shortcomings with the iPhone versions, as well as a number of vulnerabilities in e-mail programs.

These results are disconcerting -- especially when one considers just how app happy we all are. According to International Data Corp., nearly 11 billion apps were downloaded by users last year.

How to keep your phone safe

Just scaring smartphone owners doesn't do us much good, unfortunately. It's like that old joke: Everybody complains about the weather, but nobody does anything about it. Fortunately, there are some steps you can take to become a smarter smartphone owner.

"Regardless of what kind of phone you're using," explained McAfee's Wosotowsky, "read the comments section of an app you're thinking of downloading -- and look at how many times it's been downloaded. The more, the better." If tens of thousands of people have downloaded it without incident, chances are you're safe.

"Users need to become more suspicious when it comes to new friendships on social networks or installing applications," emphasized Catalin Cosoi, the head of the online threats lab at BitDefender. Think about why a certain app requires a whole slew of permissions, such as access to your GPS location or text messaging, before you install it.

Better still, I recommend trying an anti-virus/security program for your smartphone. There are several free or inexpensive apps that can not only prevent infections but also back up important personal information and help you recover your phone should you "misplace" it.

Lookout Mobile Security is a popular program and works with Android and Blackberry phones. The free version includes a lost-phone location service, backup, and scanning that analyzes apps as you download them. (For more features, a premium version is $29.99 a year.)

Still in the testing or beta stage is Norton Mobile Security for Android phones. It includes anti-theft features, anti-malware and virus scanning, as well as text message and call blocking. Blocking text messages can be a handy feature for parents, or for those of us who have been spammed via SMS. I recently received nearly 60 scam messages within a couple of minutes -- a costly attack because even though I didn't click on the suspicious links, each message I received cost me 20 cents.

Other programs to consider include the free AVG Antivirus program for Android phones. It scans handsets for malware, warns of potentially unsafe settings, and offers remote location tracking should the phone be lost (a full-featured Pro version is $9.99).

McAfee also offers WaveSecure ($19.90 a year) for Android, Blackberry, Symbian, and Windows Mobile phones. However, it doesn't include a virus scanner and instead concentrates on backing up data and wiping lost or stolen phones so that thieves can't steal personal information. On the cutting edge, BitDefender is in beta right now with SafeGo for Facebook users. The idea behind its software is to warn users of Facebook specific scams and malware attacks.

Of course the main point is to not become complacent with that snazzy new smartphone. Every model is vulnerable, including the iPhone, and the more we rely on these devices, the more valuable they become.

As McAfee's Wosotowsky warns, "Be aware that you are on the cutting edge of technology and because of that you need to be concerned with the types of things you do on the device."

In other words, don't just complain about the weather, do something about it.

Follow John R. Quain on Twitter @jqontech or find more tech coverage at J-Q.com.