The code behind the attack, called Aurora, was written in 2006, but apparently it was rarely used, which helped it evade antivirus detection for several years. The source code for this algorithm, “only seems to be found on Chinese Web sites, which suggests that the person who wrote it reads Chinese,” researcher Joe Stewart said. Google has implied that the people who hacked its computers had the support of the People’s Republic of China, but company executives have admitted that they have no proof.”]
Source: https://www.csoonline.com/article/2124751/security-researcher-ids-china-link-in-google-hack.html