Apple's ploy to gain browser market share by pushing Safari to users with an update tool normally used for security fixes failed to boost its overall share, a Web metrics company said.

Instead, Safari's share fell last month to 5.5 percent, down from March's 5.8 percent, while Microsoft's Internet Explorer increased its dominance by growing to 76 percent from March's 74.8 percent. It was the first time Internet Explorer (IE) gained share since October 2007.

In late March, Apple started using its Windows software update tool -- previously used only to provide patches for iTunes and QuickTime -- to offer Safari 3.1 to users who did not have the browser already installed. The tactic got the attention of, among others, Mozilla Corp CEO John Lilly, who blasted Apple for using the security updater to push Safari. In a long blog post, Lilly said the practice "undermines the Internet" and "borders on malware distribution practices."

A few weeks later, Apple modified the tool to separate updates for already-installed programs from offers to install new software. Mozilla saw it as a concession to Apple's critics, and applauded the change even as it asked for more. "Now Apple needs [to] stop checking the box for 'New Software' items by default," said Asa Dotzler, Mozilla's director of community development, in a post to his blog on April 17.

The use of the updater, however, did boost the share of Safari for Windows, according to Net Applications' data, which it collects from traffic to the thousands of sites run by its clients. On Windows, Safari 3.1's share tripled last month, climbing to 0.21 percent from March's 0.07 percent. Even so, Safari's overall share dipped; the vast majority of Safari users own Macs and run Mac OS X.

Firefox's share also fell in April by nearly a percentage point from the month prior. The open-source browser, which had accounted for 17.8 percent of the usage market in March, dropped to 17 percent last month. It was the largest one-month drop in the browser's market share since May 2007, and put an end to a run of five consecutive months of gains.

IE, meanhwhile, reversed its long slide last month. In April, Microsoft's browser increased its market share by more than a percentage point over March, the largest gain since Net Applications began publishing browser data in May 2006. Ironically, the bulk of IE's increase in April came from the older IE6, which boosted its share from 28.9 percent to 30 percent. The newer IE7, meanwhile, climbed just 0.1 percent during the same period.

Both Mozilla and Microsoft are working on the next versions of their respective browsers. Firefox 3.0, which is still in testing, is expected to go final before the end of June, while IE8 will wrap sometime this year, Microsoft has said.

Net Applications' browser share and trend data is available online.