Computer hackers recently shut down Sony PlayStation for weeks.
They've also breached other well-known companies, including Google and Yahoo.
Their latest target - Citibank -- where they stole the credit card information of some 200,000 customers in North America.
But on "The Early Show on Saturday Morning," personal finance expert Carmen Wong Ulrich shared advice to help you protect your personal information, and explained what to do if you learn hackers have gotten their hands on it.
If you've been hacked, she told co-anchor Betty Nguyen, "The first line of defense is always your passwords, and the information on your computer. Make sure you go right to your computer, change your log-in information and password information on everything from your credit card accounts to where you shop through retailers and your email, as well because, as we saw -- Google and Yahoo - the hackers are coming in from everywhere."
Ulrich, author of "The Real Cost of Living," said almost three-quarters of us use the same password on several accounts.
"Please stop doing that! She implored viewers. "Protect the banking part as much as you can, because the hackers will come in from the company side. But they're coming in on your side, too. It just makes it too easy if you use the same password for your banking and credit card online as for your email and retailers. It's too dangerous. So have a separate password."
Why are so many major companies getting hacked?
'We can only protect ourselves on our end so much," Ulrich observed. "Banks are trying to help us do that, for example, with new technology like fingerprint recognition for big expenses or big transactions you're gonna do online. But in terms of on their end, and their getting hacked, that's not something we can do (anything about). This is good customer service on their end. Fraud costs them millions (of dollars) a year. So, it's in their best interest to protect us.
"It's about (their) being ahead of the hackers and updating technology. That's up to them. That's what they're doing. This is the first time a bank has been hacked."
As for protecting ourselves, "The number one thing (is) those passwords," Ulrich stressed. "Please have a different password for your banking and credit cards online. That's very important. Also, use one computer, if you can, to do your banking. I know it's hard (with everyone using so many different devices). Try to do it all on one computer. That limits exposure.
"And," she underlined, "never, ever do banking or do transactions online on an open Wi-Fi. It's very tempting because it's so easy. You could be sitting in a coffee shop or the airport or wherever you are. Squatters will sit there and scour that Wi-Fi. So definitely don't do that.
"And don't use your debit card online. This runs counter (to conventional wisdom), because credit cards, people say, are bad. But a credit card protects you and your cash. Of course, there's (a) liability (limit) with your debit card. But who wants their accounts emptied of cash? Instead, use your credit card online, so at least you don't expose yourself, cash-wise."
Using smart phones do to your banking, Ulrich acknowledged, is 'super, super convenient. You can even take a picture of your checks for depositing. It's so convenient, you wonder, why not do it? Here's the thing: Be very careful. A lot of phones let you choose between your Wi-Fi or phone service to send information. Always use your phone service. If you lose your phone, check your accounts -- that's the most dangerous thing. Also, your software updates you get from your phone provider, always put those in there. A lot of them are security-related."
Ulrich also pointed to two apps that can help you in your security efforts.
"E-wallet has incredible encryption technology. It costs $9.99. ... Another one is LockBox. This is free. So if you're just looking for a place to store all those passwords -- since I told you to change them! -- this is a really good place to have good technology and very simple and easy to use."