The contracts with the private companies working on the health care website do not have any "built-in penalties" allowing her department to charge them for disappointing or faulty work, Sebelius said. However, she said the agency will not pay for incomplete work.
Republican Rep. Mike Rogers of Michigan, who chairs the House Intelligence Committee, accused Sebelius of putting the private information of Americans at risk by failing to properly test security measures on the website.
"This is a completely unacceptable level of security," he said. "You know it's not secure."
Sebelius responded that testing occurs regularly, and she told Rogers she would get back to him on whether any end-to-end security test of the entire system has ever occurred. Rogers responded that he knows there have been no such comprehensive security tests.
An internal government memo, obtained by CNN on Wednesday and written just days before the website opened, warned of a "high" security risk because of a lack of testing.
"Due to system readiness issues, the (security control assessment) was only partly completed," said the memo from the Centers for Medicare and Medicaid Services. "This constitutes a risk that must be accepted and mitigated to support the Marketplace Day 1 operations."
In an exclusive interview with CNN last week, Sebelius said Obama didn't know of the problems with the ACA's website until after the troubled launch. This was despite the fact that insurance companies had been complaining and the site crashed during a pre-launch test run.
Earlier congressional questioning
Invited to testify last week, Sebelius put it off for travel related to efforts promoting enrollment in new health insurance exchanges under the health care reforms, Obama's most significant domestic policy achievement.
One of her lieutenants -- Marilyn Tavenner, who heads the Centers for Medicare and Medicaid Services unit that oversees the HealthCare.gov website -- became the first government official to face congressional questioning on Tuesday at a House Ways and Means Committee hearing.