These hackers exploited three such zero-day vulnerabilities present in iPhones using spyware developed by a European startup, according to the TAG report published on Tuesday.

The TAG investigated several government-associated attack campaigns, which were carried out using solutions provided by companies specializing in such tools. For instance, the product of a Barcelona-based startup, Variston, was one of the tools utilized.

In one of the examined cases, attackers leveraged three zero-day vulnerabilities simultaneously. Such vulnerabilities are called zero-days because the software developers, Apple in this instance, were unaware of their existence at the time of the attack. The Variston solution was the tool used to execute this particular attack.

Google's research found that an unidentified client used the vulnerabilities to target iPhones in Indonesia. The attack started with an SMS containing a malicious link, which redirected the unsuspecting victim to an article on an Indonesian newspaper's website, while in the background, the spyware was installed on the iPhone.

Although Variston has been under Google TAG's radar before and has lost many employees over the past few years, attempts made by _TechCrunch_ to contact former employees were unfruitful due to confidentiality agreements.

While the TAG report does not name the employees, it states that Variston is "collaborating with several other organizations" in the development of spyware.

Similar surveillance methods, such as those used by the spyware Pegasus developed by the Israeli firm NSO Group, could also have been employed to monitor Hungarian individuals through exploitation of vulnerabilities on their iPhones.