'We were were astounded by the number,' says senior official
The vulnerability has already been patched by Google
The US placed Candiru on a trade blacklist earlier this month, along with fellow Israeli spyware firm NSO Group
Israeli firm Candiru, Russian security vendor Positive Technologies and Computer Security Initiative Consultancy also sanctioned
SandCat developed malware on PCs running antivirus software - which transmitted binaries of dodgy files back to Kaspersky researchers