The company disclosed the effort after several cyber security firms reported finding a malicious program dubbed XcodeGhost that was embedded in hundreds of legitimate apps.
              
It is the first reported case of large numbers of malicious software programs making their way past Apple's stringent app review process. Prior to this attack, only five malicious apps had ever been found in the App Store, according to cyber security firm Palo Alto Networks Inc.
             
 The hackers embedded the malicious code in these apps by convincing developers of legitimate software to use a tainted, counterfeit version of Apple's software for creating iOS and Mac apps, which is known as Xcode, Apple said.
              
"We've removed the apps from the App Store that we know have been created with this counterfeit software," Apple spokeswoman Christine Monaghan said in an email.

"We are working with the developers to make sure they're using the proper version of Xcode to rebuild their apps”, Monaghan added.