These attacks come as the October 17 deadline approaches for extension filers. The IRS said there was a wave of attacks just ahead of the April 15 deadline. The IRS urged tax prose to review tax preparation software settings and use all available security measures.

"This latest incident reinforces the need for all tax professionals to review their computer settings as soon as possible," IRS Commissioner John Koskinen said in a prepared statement‎. "Identity thieves continue to evolve and look for new areas to exploit‎, especially as our fraud filters become more effective.

The IRS recently issued instructions on how tax professionals can monitor their PTIN activity.