Details Emerge; Breach Will Top Record

UnitedHealth Group’s admission that sensitive information for “a substantial portion” of the America population was compromised in the cyberattack on its Change Healthcare unit sets into motion the likelihood that the incident will become the largest health data breach reported in U.S. history, surpassing the Anthem Inc. hack reported in 2015 as affecting nearly 79 million individuals.

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Change Healthcare says it processes 15 billion transactions annually and “touches” 1-in-3 patients in the U.S. The latest figures from the U.S. Census Bureau puts the nation’s total population at about 336 million.

Based on UHG’s statement Monday, “we anticipate that there will be a very large notice population, one that could potentially eclipse the number of individuals notified of Anthem breach,” with many tens of millions affected, said regulatory attorney Sara Goldstein of law firm BakerHostetler (see: UnitedHealth Group Previews Massive Change Healthcare Breach).

Healthcare sector organizations should keep tabs on UnitedHealth Group’s official breach reports to regulators – once that happens – and especially keep a close eye out for the company’s notifications to entities affected, she advised.

“Covered entities need to continue performing their reasonable diligence in accordance with their requirements under HIPAA,” she said (see: Feds Issue Guide for Change Health Breach Reporting Duties).

Reasonable diligence measures for entities include keeping abreast of latest developments at Change Healthcare and monitoring for updates from their internal IT teams or third-party cybersecurity firms regarding protected health information of their patients that potentially gets posted online, she said.

“Contact your Change Healthcare account representative to obtain information specific to your organization. Covered entities also need to document their HIPAA risk assessment for the files and update as there are new developments,” she said.

Dave Bailey, vice president at security and privacy consultancy Clearwater, agrees that organizations potentially affected by the Change Healthcare breach need to be proactive.

“Organizations have the responsibility to conduct a risk assessment to determine if data was compromised because of this incident and satisfy the regulatory reporting requirements on the breach of protected health information,” he said. “Based on everything that is known, that clock has started.”

UnitedHealth Group also reportedly confirmed to TechCrunch Monday that it had paid attackers a ransom, but has not said how much or to which cybercriminal gangs.

A Western affiliate of the BlackCat, aka Alphv, ransomware group that claimed to be behind the February attack has said UnitedHealth Group paid BlackCat a $22 million ransom – but that the affiliate claims to have been cheated out if his or her cut of the bounty. Last week another group, RansomHub, began leaking files allegedly stolen by the BlackCat affiliate, claiming to have 4 terabytes of data exfiltrated in the attack.

That listing by RansomHub was removed from the darkweb, fueling speculation that UnitedHealth Group might have paid a second ransom.

UnitedHealth Group in its statement Monday acknowledged that 22 screenshots, allegedly from exfiltrated files with some containing PHI and PII, were posted for about a week on the dark web by a malicious threat actor. “No further publication of PHI or PII has occurred at this time,” the company said.

UnitedHealth Group did not immediately respond to Information Security Media Group’s request for comment.

Attack Details Slowly Emerging

Meanwhile, details about the attack are very slowly emerging, providing insights for other healthcare sector entities facing similar threats.

That includes reporting Monday by the Wall Street Journal that hackers allegedly gained access to Change Healthcare’s network nine days before launching ransomware, and that compromised credentials on an application that allows staff to remotely access systems was the means of entry.

The tactics of the attackers come as no surprise, Bailey said. “All threat indicators identify an adversary that is financially motivated, will target an organization to steal credentials, take advantage of vulnerabilities, and operate undetected to look for data to exfiltrate and extort,” he said.

“Initial entry is often the result of credential stuffing or phishing attacks taking advantage of trusted paths to exploit coarse-grained, transparent and disconnected data protection systems,” said Anthony Cammarano, vice president of security, privacy and strategy at security firm Protegrity.

Credential compromise has recently turned into the leading and preferred path of compromise for attackers, replacing zero-day vulnerabilities, he said.

“This is often the easiest path of least resistance due to the transparent and trusted nature of our existing credentials. It is significantly hard, if not impossible, for organizations to cover every weakness and attack surface, as well as every trusted user. This creates the opportunity for an adversary to expose.”

Meanwhile, remote access applications have been particularly effective at giving attackers initial access into a victim’s network – and the average amount of time that passes before initial detection is usually closer to 100 days, said Mike Hamilton, founder and CISO of security firm Critical Insight.

“Change detected the intrusion much more quickly, however the constant stories of other organizations being compromised using remote access tools should have been an opportunity for more rigid controls in credential management, multifactor authentication, system patching and monitoring for aberrational events.”

The remote access product used to access Change Healthcare’s environment was likely either Remote Desk Protocol, a tool used by server admins to remotely manage servers that the threat group got admin level credentials for and/or STM, or scheduled task manager, a tool that server admins use to maintain servers and schedule certain required tasks, such as updates, suspects Steve Hahn, executive vice president of security firm BullWall.

“Often, 95% of the time, attackers use RDP to gain remote access to every server in the company to do almost anything they want undetected. RDP can be protected by MFA, so companies think they are secure,” he said. But when STM is used by the criminals, it becomes a way to schedule a series of events that lead up to the actual encryption, he said.

Hackers sometimes use the tool to schedule the final ransomware event to launch during hours a hospital has the fewest IT staff working, such as the middle of the night on a holiday, he said.

“This attack chain is so simple and so effective that companies simply have no hope of stopping it, “he said. “On the dark web I’ve seen criminal groups jokingly refer to RDP as the ‘Ransomware Deployment Protocol.'”

Soon after UnitedHealth Group publicly disclosed on Feb. 21 that its Change Healthcare unit had suffered a cyberattack, some experts speculated that the incident might have involved exploits of vulnerabilities in the ConnectWise ScreenConnect application (see: Change Healthcare Outage Hits Military Pharmacies Worldwide).

ConnectWise has said no link had been established between the Change Healthcare hack and any potential exploit of ScreenConnect flaws. UnitedHealth Group has yet to publicly comment on that.

Now speculation about a potential ConnectWise connection is resurfacing. “ConnectWise remote access product was reportedly compromised using credentials that were either disclosed in another data breach and used on multiple systems, or obtained through credential stuffing,” Hamilton said.

“Notably, the ConnectWise product was also vulnerable to exploit at the time and it is not clear that the server was patched, leading to some uncertainty in the initial access vector,” he said.

“Careful credential management, the use of multifactor authentication, and good vulnerability management are all key to avoiding this particular attack type,” Hamilton said.

“Importantly, when a vulnerability is announced and a patch issued for an Internet-facing product, mitigation of the vulnerability should be treated as an incident and prioritized accordingly,” he said.

Further, good monitoring of the network, endpoints and cloud properties – combined with effective incident response – are the best way to limit impact of the event and shorten the time to discovery of the compromise, he said.