If the eBay seller is a dealer of headphones and/or audio equipment, you will most likely be covered by a warranty.
Otherwise, you'll need to read the warranty itself to determine if it is transferrable.
Further complicating things, state laws often modify what is covered under warranties. If you live outside the United States, your country will most likely have laws regulating warranties, too.
Unfortunately, there are a number of variables and possible resales, such as this, can be complicated. If you want an easy answer, just buy from an authorized dealer. You will almost absolutely be covered in that case.
If you want to find a copy of the warranty before you purchase, check Shure's website, they ought to have one for you to read.