Apple has now joined WhatsApp and its parent firm Meta (previously known as Facebook) in suing NSO Group, the developer of Pegasus malware. Apple claims it’s “looking a legal ruling to prevent NSO Group from accessing any Apple software, services, or devices,” alongside providing new information about how NSO Group targeted selected iPhones via a zero-click vulnerability that researchers later called ForcedEntry.

“State-sponsored entities like the NSO Group spend millions of dollars on advanced surveillance technology without adequate responsibility,” says Senior Vice President of Software Engineering Craig Federighi in a statement. That must be changed… Apple products are the safest consumer electronics on the market, but private corporations that create state-sponsored spyware have grown even more destructive.” Apple and WhatsApp aren’t alone in their legal battle with NSO Group; last year, Microsoft and Google joined Apple and WhatsApp in backing Facebook’s complaint.

According to Apple’s news release, Pegasus spyware is created to allow authorities to remotely control a phone’s microphones, cameras, and other information on both iPhones and Androids. As per claims from a journalistic alliance called the Pegasus Project and Apple’s complaint published previously this year, it’s also meant to infiltrate phones without demanding any interaction from the user and without leaving a trace.

Apple’s complaint explains how the assault worked: NSO would transmit data to a target via iMessage after identifying that they were using an iPhone that was fraudulently constructed to switch off the iPhone’s logging using the Apple IDs it created. This would allow NSO to install the Pegasus spyware invisibly and control the data acquired on the phone. According to Apple, the vulnerability that NSO was exploiting was fixed in iOS 14.8. NSO was transmitting files that took advantage of a flaw in the way iMessage handled GIFs and PDFs.

NSO was recently added to the US Entity List, limiting the means by which American corporations can sell or contribute technology to NSO. According to an article by the MIT Technology Review, the ban has had a significant negative impact on NSO Group’s staff morale as well as its capacity to conduct business. As per the report, the corporation must receive approval from the US government to purchase products such as Windows computers and iPhones, and the administration has stated that its default approach is to deny such requests.