The hackers breached into Microsoft's internal network and used an internal account to view source code but as it had view-only access, they could not alter the codes.
As Donald Trump remained mum on the alleged Russian-backed cyberattacks that compromised national security, Republican and Democrat senators have called retaliation.
The malware can steal personal information including SMS, GPS location, photos and contacts that can be used for extortion and future phishing attacks.
By diverting signaling messages, China is allegedly tracking and intercepting calls of thousands of Americans, claims mobile network security expert Gary Miller.