A hacker broke into HealthCare.gov last month and uploaded malware onto the site's test servers, a statement from the Department of Health and Human Services said.

"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. We have taken measures to further strengthen security," the statement said.

The breach of the server that is used to test code for the website was investigated by the Department of Homeland Security, the FBI and other agencies, the statement said. It added that department officials briefed congressional staff about the incident, which was noticed on Aug. 25.

The Wall Street Journal reports:

"The attack comes as the federal government and insurance companies prepare for open enrollment, which begins Nov. 15. It is likely to be seized on by Republican lawmakers, who oppose the law, in fall campaigns as another sign of the health law's flaws. HealthCare.gov suffered from crippling technology problems when it launched in October, though the government has since improved the site."

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