Officials said that they have found no evidence that the hacker had access to any personal data.
"Our review indicates that the server did not contain consumer personal information; data was not transmitted outside the agency, and the website was not specifically targeted," the Department of Health and Human Services said in a written statement Thursday. "We have taken measures to further strengthen security."
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Politicians will likely hold up the hacking as another flaw in the health law.
This is not the first time a computer server associated with the Affordable Care Act implementation has been hacked: In July,National Review Online reported that the Vermont health exchange's development server suffered a similar attack.
—By CNBC staff. Reuters contributed.
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