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As if there weren’t enough reminders for Internet users to frequently change their passwords, this week came news that more than 2 million accounts on some of the most popular social media sites have been compromised in a hack that began in October and may be ongoing.

Chicago-based cybersecurity group Trustwave said that more than 1.5 million website login credentials and more than 300,000 email passwords were stolen from a server in the Netherlands. More than 300,000 of the passwords were snatched from Facebook Inc. (NASDAQ: FB), almost 60,000 from Yahoo! Inc. (NASDAQ: YHOO) and more than 50,000 from Google Inc. (NASDAQ: GOOG). Twitter Inc. (NYSE: TWTR) and LinkedIn Corp. (NASDAQ: LNKD) were not spared, with more than 21,000 and more than 8,000, respectively, acquired by the malware.

Also hit was payroll services provider Automatic Data Processing Inc. (NASDAQ: ADP), with nearly 8,000 passwords stolen.

All the companies were notified of the breach, and ADP, Facebook and others have reset the effected passwords of the compromised accounts. Accounts in nearly 100 countries were affected. Most of those accounts, more than 1.8 million, were in the Netherlands. More than 1,900 of the stolen passwords were from accounts in the United States.

Still, better safe than sorry when it comes to your passwords. Besides changing them frequently, using more secure passwords is always better. According to Trustwave, the most common passwords in this particular hack were along the lines of 123456, password, admin and 111111. Do any of those look familiar? If so, it may be time to rethink your password strategy.