Security Experts:

Identity Thieves Use Stolen SSNs in IRS Attack

The U.S. Internal Revenue Service (IRS) revealed on Tuesday that identity thieves abused its Electronic Filing PIN application in an attempt to generate PINs for stolen social security numbers.

The E-File PIN application hosted on allows taxpayers to generate a PIN that they can use to file tax returns online. When obtaining a PIN, users must provide their name, date of birth, SSNs and mailing address.

According to the agency, identity thieves obtained this information from other sources and used an automated bot to generate PINs for the E-File service. The IRS detected unauthorized attempts using roughly 464,000 unique SSNs, 101,000 of which were successful in generating PINs.

Impacted individuals will be notified via mail and their accounts have been secured against tax-related identity theft. The agency said its systems were not breached and no taxpayer data was compromised.

“IRS cybersecurity experts are currently assessing the situation, and the IRS is working closely with other agencies and the Treasury Inspector General for Tax Administration. The IRS also is sharing information with its Security Summit state and industry partners,” the IRS said in a statement.

The agency pointed out that the attack took place in January and it’s not related to the outage suffered by its tax processing systems last week.

This was not the first time cyber thieves used information obtained from other sources to abuse the IRS’s online services. In May 2015, the agency informed more than 100,000 taxpayers that their accounts on the Get Transcript system were accessed by unauthorized parties using stolen information. Investigators later determined that the total number of accounts breached in the attack exceeded 300,000.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.