The government's own watchdogs tried to hack into HealthCare.gov earlier this year and found what they termed a critical vulnerability – but also came away with respect for some of the health insurance site's security features.

“The Affordable Care Act changed the rules on how health insurance plans dealt with pre-existing conditions, outlawing the practice of turning away patients with expensive conditions or charging them a drastically higher cost for coverage. But an editorial alleges some health insurance companies operating on the new marketplaces created by Obamacare may have found a loophole that allows them to discourage sick patients from enrolling in a specific plan.
The change has to do with how drugs are categorized in health systems. From the editorial published online at the American Journal of Managed Care:
“For many years, most insurers had formularies that consisted of only three tiers: Tier 1 was for generic drugs (lowest copay), Tier 2 was for branded drugs that were designated “preferred” (higher co- pay), and Tier 3 was for “nonpreferred” branded drugs (highest copay). Generic drugs were automatically placed in Tier 1, thereby ensuring that patients had access to medically appropriate therapies at the lowest possible cost. In these three-tier plans, all generic drugs were de facto “preferred.” Now, however, a number of insurers have split their all-generics tier into a bottom tier consisting of “preferred” generics, and a second tier consisting of “non-preferred” generics, paralleling the similar split that one typically finds with branded products. Copays for generic drugs in the “non-preferred” tier are characteristically much higher than those for drugs in the first tier.””