Software created by Israel-based NSO Group was reportedly used to hack at least nine iPhones belonging to US State Department officials, using a technique which Apple terminated with a software update.

Sources quoted by Reuters stated the hacks were carried out through a graphics processing vulnerability which Apple corrected in September. Before the fix, the NSO Group spyware could allegedly be sent to the iMessage app and installed without any action by the iPhone user.

NSO Group sells its software to intelligence and security agencies in a number of countries. It told Reuters it cancelled access for relevant customers based on the latest report about suspected phone hacks.

The US officials were reportedly involved with Uganda, where several of them were when their phones were hacked.

Earlier this year, NSO Group claimed it was “technically impossible” for smartphones registered with US network operators to be infected.

Apple sued NSO Group last month, accusing it of illegally spying on iPhone users and seeking a permanent injunction against it.