Lookout Security launched its free Ad Network Detector tool yesterday that scans Android devices for evidence of apps that use any of 35 different ad networks, and tells users what kinds of ads will be displayed and what user information those networks collect.

The app is a follow-up to an earlier program Lookout released two weeks ago, Push Ad Detector, that scanned Android smartphones for signs of only six ad networks.

Ad Network Detector is Lookout's response to the rise in very aggressive behaviour by ad networks that some developers rely on to make money on their for-free Android software.

"The intent of this product is to clarify for users the behaviour of applications that display ads," said Derek Halliday, senior product manager for security at San Francisco-based Lookout. "And two, to show users what privacy and information collection apps and their ad networks are doing. We're trying to provide transparency."

Last month, Lookout butted heads with the much larger security firm Symantec when the latter initially called out 13 apps in the Android Market as malicious . Lookout quickly countered, saying that Symantec had "overblown" the story , arguing that the apps' behaviour - which included adding icons to the Android desktop and modifying bookmarks in the device's browser - was consistent with some of the pushier ad networks.

Symantec later retracted its malware assertions.

Halliday acknowledged that the privileges demanded by some apps, and the results of their ad networks' operations, has resulted in "a fair amount of confusion" on the part of users, but rejected the idea that it was Google's fault.

"We are absolutely proponents of the monetisation of apps through ad serving," Halliday said. "We definitely understand the means through which consumers get these free apps. But the problem isn't with the platform. It's because the mobile ecosystem is growing, and some people are pushing the boundaries. We're simply in the early stages of trying to figure out what's appropriate."

Lookout's Android security software, for instance, does not flag apps that exhibit aggressive ad serving.

As others have done, Halliday characterised the problem as similar to what went on years ago in the desktop world when the behaviour of pop-up ads was debated by security experts.

"The way I would frame it is that it's somewhat similar to the evolution of ad serving on desktop browsers, where there were pop-ups like crazy, and sites that changed the home page or added toolbars," agued Halliday. "That's symptomatic of an emerging, growing industry."

The timing of Lookout's release of Ad Network Detector wasn't lost on Halliday.

Google has committed to supporting "Do Not Track" in its Chrome desktop browser as the White House pushed for a privacy bill of rights and promised to introduce new online privacy legislation.

"That topic really ties in to mobile privacy," said Halliday, "because so much of what goes on online from a smartphone or tablet happens not through the browser, but through apps."

Ad Network Detector can be downloaded free of charge from Google's Android Market.

Halliday said that Lookout has no plans to follow that with a similar app for Apple's iOS operating system.