Local Networks Go Global When Domain Names Collide

The proliferation of new top-level domains (TLDs) has exacerbated a well-known security weakness: Many organizations set up their internal Microsoft authentication systems years ago using domain names in TLDs that didn’t exist at the time. Meaning, they are continuously sending their Windows usernames and passwords to domain names they do not control and which are freely available for anyone to register. Here’s a look at one security researcher’s efforts to map and shrink the size of this insidious problem.



At issue is a well-known security and privacy threat called “namespace collision,” a situation where domain names intended to be used exclusively on an internal company network end up overlapping with domains that can resolve normally on the open Internet.


Windows computers on a private corporate network validate other things on that network using a Microsoft innovation called Active Directory, which is the umbrella term for a broad range of identity-related services in Windows environments. A core part of the way these things find each other involves a Windows feature called “DNS name devolution,” a kind of network shorthand that makes it easier to find other computers or servers without having to specify a full, legitimate domain name for those resources.


Consider the hypothetical private network internalnetwork.example.com: When an employee on this network wishes to access a shared drive called “drive1,” there’s no need to type “drive1.internalnetwork.example.com” into Windows Explorer; entering “\drive1” alone will suffice, and Windows takes care of the rest.


But problems can arise ..

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