Security researchers believe they have found a major security flaw in Google's Android mobile operating system, which could affect up to 99 percent of Android phones that are currently being used by consumers.

In a report written by the Bluebox Security research firm, chief technology officer Jeff Forristal said the flaw gave hackers a "master key" to the Android system through an exploit in the Google Play applications store verification system. Since the release of Android 1.6 in 2009, there has been a flaw in the company's security in the way Android applications verify changes to their code. The weakness, according to The Washington Post could leave up to 900 million deices open to hackers who could turn any legitimate application into a malicious Trojan without flagging any security concerns with or getting the attention of the Google App store.

This means if anyone breaks into an app through this method, he or she would have access to the data the application collects. This could mean websites, or even financial information. The hacker could even go as far as to take over the normal functions of the device since it would be granted the same access to the phone as any legitimate application.

Android is the mobile operating system of choice for about 75 percent of the world's smartphones. This means that this security flaw has the potential to be exploited and affect the system globally.

The report mentions a few manufactuerers who have already released fixes for the problem. The most notable of which is the Android operating system's flagship, top of the line smartphone the Samsung Galaxy S4.

Security on the operating system is a difficult area for manufacturers because one of the biggest appeals of Android is the open nature of the system. While it makes it appealing for developers, it also makes it so that intimate knowledge of its inner workings is available for almost anyone willing to look.