Philadelphia is believed to be a new version of the ransomware known as Stampado.
The method of attack is using a shortened URL sent through a spear-phishing email. Forcepoint's Roland Dela Paz said he had come across a case where an attack was attempted on a hospital in Oregon and Southern Washington.
If a user clicked on the link in the email, then a malicious Microsoft Word file would be downloaded from a personal storage site.
The ransom message seen after the new variant of Philadelphia ransomware finished encrypting files on a Windows system.
If the user clicks on any of the icons, a variant of the Philadelphia ransomware is downloaded and executed.
"Believed to be a new version of the Stampado ransomware, Philadelphia is an unsophisticated ransomware kit sold for a few hundred dollars to anyone who can afford it," Dela Paz wrote. "Recently, a video advertisement of Philadelphia surfaced on YouTube."
He said upon execution, the dropped Philadelphia variant got in touch with its command and control server. System information including the operating system, username, country, and system language were transmitted and the C&C server then generated a victim ID, a Bitcoin wallet ID and the Bitcoin ransom price.
"Likewise, the ransomware C2 also contained 'hospital/spam' in its path. Such wordings would imply that this is not an isolated case; but that the actor behind the campaign is specifically targeting hospitals using spam (spear phishing emails) as a distribution method."
He added that based on the directory timestamp found on the ransomware C2, it looked like this particular campaign against hospitals started in the third week of March.
Forcepoint principal security analyst Carl Leonard said: “While processing our open source intelligence feeds we discovered Philadelphia, currently a cheap, poorly written ransomware that is available cheaply to script kiddies.
"Although the ransom is currently only 0.3 BTC, the command and control paths suggest that the actor is targeting hospitals for this campaign so there are likely to be other targets.
"While this might not seem like a huge attack on the healthcare sector, should this trend catch on, collectively this represents a huge risk to the industry.”