Recently, malicious apps entered Google Play, the Android app store, as the open source nature of the store continues to bring about positive and negative consequences. While not a new problem, apps with malicious software for stealing information - or intrusive in-app advertisements - can now be identified. Help is at hand with Lookout developing software for uninstalling "spammy" apps.

Lookout, a security firm in San Francisco, is developing a malware removing app. Lookout CTO Kevin Mahaffey told CNET News "You have networks that without your knowledge, can take your e-mail address or phone number and then send it for who knows what to some server someplace." Mahafrey added that "Anytime that advertising networks is putting advertisements where you don't expect them, then we think that's a problem."

Free apps generally use advertising to generate revenue.

Lookout has developed a free app for download and it identifies apps with the intrusive advertisements or invasion into personal information. Post this, the apps can be uninstalled manually.

The firm estimates 5 percent of apps in Google Play are stealing information, potentially several millions of downloads, implying that user's information is taken. Where the stolen information goes is unknown, but it probably isn't where a user would like.

Visiting the Lookout website presents a single-page guide on how to avoid spamming advertisements. The guide is also available in a PDF format.

Rip-offs of popular games like Plants vs. Zombies surfaced on Google Play recently and a malicious app spamming messages to contacts without a user's permission. The app quickly got removed, but the invasion into arguably the world's biggest mobile operating system is worrying.

The Russian app sent SMS messages to contacts unknowingly. It also managed to surface on the iOS App Store, which is not as common due to Apple's strict vetting process. The company had famously denied Google from offering Google Voice in the store and doesn't allow e-mail client Sparrow to support push notifications.

Ultimately, use common sense when downloading an app. Does it have user reviews? Is the developer name recognizable? If not, Google search the name. Does the app have pictures and/or a description? Does the developer have a website? Usually, it'll be clear if apps are genuine products; so, don't worry about deeply researching every app.