Most Android applications are just too invasive privacy- and security-wise, according to separate studies out this week from Bit9 and Juniper Networks that quantify just how risky some Android apps can be to privacy and security due to their promiscuous permission policies.

Some 26 percent of Android apps in Google Play can access personal data, such as contacts and email, and 42 percent, GPS location data – in many cases, whether they need it or not. That's the finding from some 412,000 Android apps analyzed by Bit9. Other findings from the research: 31 percent of the apps access phone calls or phone numbers, and 9 percent employ permissions that could cost the user money, such as incurring premium SMS text message charges.

Harry Sverdlove, CTO of Bit9, says there's a concern that some percentage of the one-fourth of apps with overly permissive access could be malicious. "I know Google Play pulls certain apps if they are discovered to be bad. But what's interesting about the mobile world is that [risky] apps aren't always malicious," Sverdlove says. In a BYOD enterprise, the key is apps with access to potentially sensitive information could be exposed or abused, he says.

"In BYOD, another form of maliciousness or risk is are they running apps that have access to information that could be damaging if it's not properly secured, or gets stolen and put on the network? If an app has access to my email and may not be malicious, it still has access to confidential email I'm using for business, which could have financial information in it," for example, he says.

Juniper, meanwhile, studied more than 1.7 million apps -- free and paid -- in Google Play between March 2011 and September 2012, and found that free apps are 401 percent more likely to track location than paid ones, and 314 percent more likely to access user address books than apps you pay for.

"If an app had ability to perform a specific function ... is that justifiable? Often, [they] are, and sometimes they are not," says Dan Hoffman, chief mobile security evangelist for Juniper. "It's OK for a free app to check location if they want to advertise. That's reasonable. But what's not is not being transparent and clear [about necessary permissions], and not providing the end user with really good data to make decisions" on whether to download the app, he says.

Why the aggressive power-grab of information by so many apps? While it may be about generating advertising revenue for free apps, in other cases it's just poor app development practices, security experts say. Just like in many software scenarios, convenience and form factor often take precedence over security, Bit9's Sverdlove says.

Juniper's Hoffman echoes the same sentiment. "It has a lot to do with development practices and how an app is developed. Requesting a permission to do something is not an accident ... there's a reason those permissions are there," Hoffman says.

Whether it's poor code-writing or intentional invasiveness, these apps can cause real trouble for users as well as their employers. Juniper found that nearly 7 percent of free apps can access address books, 2.6 percent, can send text messages without the user knowing, 6.4 percent can make calls, and 5.5 percent have access to the device's camera.

And interestingly, Juniper found only a small percentage of free apps actually using information they collected for the phones to serve up third-party ads. The report also found that certain categories of apps are more invasive than others. Cards and casino games and racing games were the worst offenders: 84 percent of cards and casino games can use the phone's camera and 85 percent can send text messages, while 99 percent of the racing apps can send SMS messages, half can use the camera, and 95 percent can place calls.

The full Juniper report is available here, and the full Bit9 study, here.

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