Alexander: How dangerous is ransomware? Damages are growing

Q: As a businessperson, I'd like to better understand CryptoWall, the malicious program you wrote about (tinyurl.com/z43tzdw) that encrypts files on a PC and holds them for ransom. Is it what computer security firms call an "advanced persistent threat"? After it's downloaded, is it installed on a single PC or can it move from one PC to another? What protection is there against it besides making file backups and running antivirus software?

Gaurav Khanna, ​Mumbai, India

A: CryptoWall qualifies as an "advanced persistent threat" because it's the latest version of a series of successful ransomware products that include Cryptorbit and CryptoLocker. As of 2014, the latter had been used to attack more than 200,000 computers worldwide, and it collected more than $27 million in ransom during its first two months on the Internet (see tinyurl.com/zefpn86). Last year, the FBI said CryptoWall was responsible for more than $18 million in ransom fees, computer repairs and other costs (see tinyurl.com/p35cpr8).

CryptoWall is even more dangerous than it appears. Besides encrypting files on a PC, it can also encrypt the PC's backup files if they're stored on an attached storage device, such as an external disk drive, a network drive or a cloud storage service (such as Google Drive or Dropbox.)

The good news is that CryptoWall doesn't replicate itself from one PC to another; it must be downloaded. As "Trojan" malware (named for the Trojan Horse), it pretends to be legitimate downloadable software.

The best defense against CryptoWall is to use up-to-date antivirus software, avoid opening unfamiliar e-mail or visiting questionable websites and store PC backup files on a device that's not attached to the PC.

Q: I use a Kindle Fire tablet computer to access the Internet and play games online. When I first got the tablet, I got a single pop-up advertisement between games of solitaire, but lately I get as many as 20. How can I stop these pop-ups?

A: Change the privacy settings in the Kindle Fire's Web browser, called Silk. You can choose to always allow pop-ups, never allow them or require that Silk ask your permission before opening them. See tinyurl.com/jxupsmp.

Q: On Windows 10, the slide show has a five-second interval between slides. How can I change it to 10 or 11 seconds?

Robert Tarring, Sunrise, Fla.

A: Type "run" into the search box at the lower left of the Windows 10 screen. From the menu choose "Run," and in the resulting box type "control/name Microsoft.Personalization/page pageWallpaper" and click OK. In the next menu, set "change picture every" to 10 seconds.

Q: My Windows Vista PC received a notice that it will soon stop receiving updates for Google's Chrome browser. What are my options?

A: Google next month will stop providing updates for that version of Chrome, as well as those for Windows XP and Macintosh OS X 10.6, 10.7 and 10.8. You can stay with Chrome or switch to a browser, like Mozilla Firefox, that's still being updated for Vista.