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Lack of MFA Implementation Likely Caused Medibank Data Breach
19 June 2024 at 16:52
The Sequence of Events in the Medibank Breach
The attack on Medibank began when an IT service desk operator at a third-party contractor used his personal browser profile on a work computer and inadvertently synced his Medibank credentials to his home computer. This home device was infected with information-stealing malware, which allowed hackers to obtain these credentials, including those with elevated access permissions. The attackers first breached Medibank’s Microsoft Exchange server using these credentials on August 12, 2022, before logging into Medibank’s Palo Alto Networks Global Protect VPN. Incidentally, the VPN did not require multi-factor authentication (MFA), making it easier for the attackers to gain access. It was only in mid-October that Medibank brought in a threat intelligence firm to investigate a Microsoft Exchange ProxyNotShell incident, when they discovered data was previously stolen in a cyberattack."During the Relevant Period, the Admin Account had access to most (if not all) of Medibank's systems, including network drives, management consoles, and remote desktop access to jump box servers (used to access certain Medibank directories and databases)." - the OAIC report.
Security Failures and Missed Alerts
Lack of Multi-Factor Authentication (MFA)
One of the critical failures in the Medibank breach was the health insurer’s neglect to implement MFA for VPN access. The OAIC report said that during the relevant period, the VPN was configured to allow access with just a device certificate or a username and password. It did not require the additional security layer provided by MFA. This oversight significantly lowered the barrier for unauthorized access.Operational and Alert Management Failures
Despite receiving several security alerts from their Endpoint Detection and Response (EDR) software about suspicious activities on August 24 and 25, these alerts were not appropriately triaged or escalated. This delay allowed the attackers to continue their operations undetected for an extended period, which ultimately led to the exfiltration of approximately 520 gigabytes of sensitive data from the company's MARS Database and MPLFiler systems.Data Compromised and Consequences
The stolen data included highly sensitive information such as customers' names, dates of birth, addresses, phone numbers, email addresses, Medicare numbers, passport numbers and extensive health-related data. The exposure of such information has severe implications for the affected individuals, ranging from identity theft to potential misuse of medical data in various frauds and scams. The attackers linked to the ransomware gang BlogXX, which is believed to be an offshoot of the notorious REvil group, leaked the data on the dark web. This incident not only caused significant distress to millions of Australians but also highlighted the grave consequences of inadequate cybersecurity measures.Legal and Regulatory Actions Follow
The OAIC said that Medibank was aware “of serious deficiencies in its cybersecurity and information security,” prior to the hack. For example, citing an Active Directory Risk Assessment report from Datacom in June 2020, OAIC said Medibank had an excessive number of individuals who had access to Active Directory (being the Microsoft directory service used for management of all Medibank users, group policies and domains)."A number of individuals had been given excessive privileges to perform simple daily routines, and that MFA had not been enabled for privileged and nonprivileged users which was described as a “critical” defect."
Given the nature and the volume of the data Medibank stores and collects, “it was reasonable” for the company to adopt the security measures recommended by Australia’s privacy regulator, but “these measures were not implemented, or, alternatively, not properly implemented or enforced, by Medibank,” OAIC said.
Thus, in response to the breach and the negligence that led to it, Australia's data protection regulator OAIC, announced legal action against Medibank for failing to protect personal information. The company faces potential fines exceeding AU$2 million.A spokesperson for the health insurer did not detail the plan of action against the lawsuit but earlier told The Cyber Express that ”Medibank intends to defend the proceedings.”
