U.S. government security experts say they are increasingly worried about the threats to law enforcement agencies using older versions of Android. A document prepared by the FBI and the Department of Homeland Security marked \"for Police, Fire, EMS and Security Personnel\" was obtained by Public Intelligence, a group focused on releasing government information to the public. The document said upwards of 44 percent of Android users worldwide are still using Android versions 2.3.3 to 2.3.7, which still contain security vulnerabilities fixed in later versions, the document said, CNET reported Tuesday. The document does not state how many U.S. government agencies are using Android, whether older or newer versions, on their networks. Android is a \"primary target for malware attacks due to its market share and open source architecture,\" the document states, and increasing use of mobile device use by government workers \"makes it more important than ever to keep mobile [operating systems] patched and up-to-date.\"