The Washington Post reports:

Russian government hackers engaged in a sweeping series of breaches of government and private-sector networks have been able to penetrate deeper into Microsoft’s systems than previously known, gaining access to potentially valuable source code, the tech giant said Thursday.

The firm previously acknowledged that it had inadvertently downloaded a software patch used by Russian cyberspies as a potential “back door” into victims’ systems. But it was not known that the hackers had viewed the firm’s source code, or the crucial DNA of potentially valuable, proprietary software.

Microsoft, however, did not specify what type of source code was accessed. The intruder compromised an employee account through which it viewed the code, the firm said. [Continue reading…]