The company did not specify how it had come to know of these vulnerabilities. It is common for those who provide knowledge of critical bugs to be acknowledged in security bulletins.
March was the last month for which such bulletins were issued in the same style as they have been for more than a decade; from this month, Microsoft changed the style of issuing details of its monthly security updates.
On Friday, the Shadow Brokers released a number of what it said were NSA exploits for many versions of Windows and also details of what were said to be NSA intrusions into the SWIFT banking system.
But three exploits — going by the names EnglishmanDentist, EsteemAudit, and ExplodingCan — were not reproducible in supported products, Misner said. Hence they had not been patched.
This meant that "customers running Windows 7 and more recent versions of Windows or Exchange 2010 and newer versions of Exchange are not at risk. Customers still running prior versions of these products are encouraged to upgrade to a supported offering".
While home and small business users, who generally patch as soon as possible, may be protected against these exploits, bigger businesses generally take a while to patch because they have extensive testing to be done, and may still be vulnerable. Two months is generally about the standard time taken for testing by bigger firms before patching.
The Microsoft statement has led to security researchers speculating how the company came to be aware of these exploits and whether the NSA was the informant. There has also been speculation that Microsoft may have paid the Shadow Brokers to obtain knowledge of the exploits.
I wonder why no one is stating the most obvious theory for how MS learned about the SB bugs: they bought the dump from the auction— mdowd (@mdowd) April 15, 2017
The abrupt cancellation of security updates in February is suspected of being linked to Microsoft's becoming aware of these exploits, with the theory being that the issue of patches was delayed until March to ensure that all the exploits against supported products were fixed.
Deciphering conclusions in the first hours of a nation-state exploit dump in an information vacuum means some initial assumptions were wrong— SwiftOnSecurity (@SwiftOnSecurity) April 16, 2017
Security researchers, who had claimed that the release of the exploits created a dangerous situation for Windows users, said they had tested without the patches from March, as there was no indication that these patches had fixed the Shadow Brokers' exploits.