Data thieves hacked Internal Revenue Service’s (IRS) website to get tax return information concerning 100,000 households, an IRS commissioner said on Tuesday.
Hackers had targeted the "Get Transcript" online application of the website 200,000 times from February to May, taking information about past tax returns of victims to benefit from refunds with fake papers.
“Get Transcript,” is an application in which users are required to provide information such as Social Security numbers, dates of birth, tax filing status and street addresses to get access to their tax returns.
Koskinen said it was possible to answer these questions by using information collected from the victim’s social media accounts.
"In all, about 200,000 attempts were made from questionable email domains, with more than 100,000 of those attempts successfully clearing authentication hurdles," IRC Commissioner John Koskinen said.
Koskinen said criminal investigations have been continued to reveal attackers.
"We're confident these are not amateurs. These are actually organised crime syndicates that not only we but everyone in the financial industry are dealing with," Koskinen said.
IRS said hackers can easily steal identities of victims using tax returns data, but they already have significant personal information concerning taxpayers.
“Taxpayers must know that the information they send to the IRS is secure,” Senate Finance Committee Chairman Orrin Hatch, R-Utah said in a statement shortly after the IRS commissioner's announcement.
“And hackers who would steal that information must know that they will suffer severe consequences for their crimes,” Hatch added.
Reports of data theft are common in the US. JPMorgan Chase as well as mega-retailers Target and Home Depot have also had to deal with cyberattacks.