System Design Autopsy: How 1 Legacy Portal Cost $1.6B (Change Healthcare Analysis)

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The digital nervous system of American healthcare collapsed in February 2024.

Change Healthcare, a payment processor handling 50% of US medical claims, was hit by ransomware. The impact was $1.6 Billion in direct losses.

But this wasn’t a zero-day exploit. It was a failure of basic System Design and Identity Management.

I did a full architectural breakdown of the incident here:




The Architecture of Failure

If you prefer reading, here are the 3 key design flaws that enabled this disaster:



1. Identity as the Perimeter (The Failure)

The attackers gained entry via a legacy Citrix remote access portal. Crucially, this portal did not have MFA (Multi-Factor Authentication) enabled. It was a “zombie” service—forgotten by the modernization teams but still live on the internet.



2. The “Blast Radius” Problem

Change Healthcare was a recent acquisition by UHG (UnitedHealth Group). However, the networks were integrated without sufficient Bulkheads (isolation boundaries).

  • The Result: When the infection was detected, UHG couldn’t isolate just the infected node.
  • The Response: They had to physically sever connectivity for the entire platform, causing a nationwide outage.



3. Lateral Movement

Because the internal network lacked “Zero Trust” principles, once the attackers bypassed the Citrix login, they moved laterally across the infrastructure with ease, encrypting databases that should have been segmented.



The Lesson

Complexity is the enemy of security. This wasn’t a failure of advanced cryptography; it was a failure of Inventory Management and Fault Domain isolation.

I publish a new System Design Autopsy every Thursday. Subscribe to the YouTube Channel for the next deep dive.



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