IRS agents accidentally made ”tens of thousands” of Social Security numbers available online, according to a recent report from National Journal and Public.Resource.org.

“The identifying numbers were on the Internet for less than 24 hours after being discovered, but the damage was done,” National Journal reports, citing an audit from Public.Resource.org.

“And unfortunately, the data-breach concerns some of the most sensitive types of transactions: Those made by nonprofit political groups known as 527s,” the report adds.

National Journal’s Brian Fung explains:

Every so often, 527s have to file tax forms to the IRS, which then get added to a database. The database itself is hardly a secret; the IRS has been sending updated records routinely to Public.Resource.org and other public-interest groups, and it’s a favorite among political reporters.

But when the IRS told the group’s founder, Carl Malamud, to disregard the Form 990-Ts included in the agency’s January release, he took a closer look at the files in question.

Malamud took a closer look at the breach of information and promptly contacted agency officials to let them know that they had posted sensitive information to a government website.

But that’s not all.

“Just the day before, Malamud had filed another letter to the agency describing a problem with the 990-Ts,” Fung notes.

“Of over 3,000 tax returns contained in the January update, 319 contained sensitive data the agency should have scrubbed, Malamud wrote in the July 1 report that he filed to the inspector general’s office. In that mixup, some 2,319 social security numbers—perhaps more—were revealed,” he adds.

From Malmud’s July 1 report:

To determine the extent of the exposure, we’ve analyzed our logs and have also analyzed the data received from the IRS. We maintain a privacy registry based on any clicks made on the privacy cover sheet on the top of each return. That registry indicates that 8 clicks were made from 4 unique IP addresses. However, none of those resulted in privacy complaints and could have been made by an automated process.

In addition, we examined our FTP and HTTP logs. We only maintain a 7-day window for HTTP logs and did not see any HTTP-based access that was not from a search engine crawler. For the FTP logs (which indicates bulk download activity), we did not see extensive activity for the January directory, but it was clear that at least one copy of the DVD ISO image (the image of the original DVD) had been transferred.

Public.Resource.org immediately removed the compromised 990-Ts from its site and uploaded the redacted versions. But it was still a full day before the IRS removed the sensitive info from the government site.

“Calling the IRS’s efforts at data security ‘unprofessional and amateur,’ Public.Resource.org is requesting that the IRS shut down the entire 527 database to prevent further lapses,” Fung writes.

“In an email, Malamud told me that the IRS has, in fact, shut down the database—but that it should also reopen it as soon as possible in the interest of transparency,” he adds.

Click here to read the full National Journal report.

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