It seems each day that passes brings new technology and an increasing dependence upon it. The medical field is no exception; medical professionals rely upon technology to provide them with accurate information and base life-changing decisions on this data. In recent years there has been more attention paid to the security of medical devices; however, there has been little research done on the unique protocols used by these devices. In large, health care systems medical personnel take advantage of to make decisions on patient treatment and other critical care, use central monitoring stations. This information is gathered from many devices on the network using uncommon networking protocols. What if this information wasn't accurate when a doctor prescribed medication? What if a patient was thought to be peacefully resting, when in fact they are under cardiac arrest? McAfee's Advanced Threat Research team has discovered a weakness in the RWHAT protocol, one of the networking protocols used by medical devices to monitor a patient's condition. This protocol is utilized in some of the most critical systems used in hospitals. This weakness allows the data to be modified by an attacker in real-time to provide false information to medical personnel. Lack of authentication also allows rogue devices to be placed onto the network and mimic patient monitors. This presentation will include a technical dissection of the security issues inherent in this relatively unknown protocol. It will describe real-world attack scenarios and demonstrate the ability to modify the communications in-transit to directly influence the receiving devices. We will also explore the general lack of security mitigations in the medical devices field, the risks they pose, and techniques to address them. The talk will conclude with a demonstration using actual medical device hardware and a live modification of a patient's critical data.