Rootkits, used by hackers to hide malicious software, are on the rise and becoming more complex, according to security company McAfee. In the first quarter, the number of rootkits seen by McAfee’s Avert Labs grew by 700 percent, compared with the same period last year, the company said Monday. Its research into “stealth techniques” also covered cloaking technology bundled with commercial programs, such as Sony BMG’s antipiracy tool, and with potentially unwanted software such as adware. Full Story