Community Health Systems (CHS) recently revealed that hackers have compromised their computer network and stolen personal information of around 4.5 million patients.The report says the attackers have breached the CHS network in between April and July. Mandiant, the company that did the forensic investigation found that the group responsible for the "Advanced Persistent Threat" attack is originated from China.The compromised information includes patients names, phone numbers, Social Security Numbers and other details.The company claims that no patient credit card, medical or clinical information has been taken.According to TrustedSec, hackers have exploited the infamous OpenSSL "heart bleed" vulnerability to compromise the CHS network."Attackers were able to glean user credentials from memory on a CHS Juniper device via the heartbleed vulnerability (which was vulnerable at the time) and use them to login via a VPN." TrustedSec explained.