What are the biggest cybersecurity challenges in SMEs?

Since networking is so entwined in cybersecurity I thought this could be a good place to ask. I was wondering what are some of the most pressing challenges in cybersecurity for smaller and medium size businesses? This is particularly interesting to me since SMEs may not be aware of all the cyberthreats out there and may not be prepared at all, it could be also that they are not knowledgeable enough to care.