Weird docs crawled by Google and effect

Have you seen that?

[silverbytes]

Checked out my logs and I see googlebot came and crawled some docs really don't exist on my site.

In between real documents,
there are documents with garbage names like:

/iykhzrlzhsyy.html
/ornyzyyvmkx.html
/qbgyvvpu.html
/scxlolrcpxslocm.html

Those docs of course doesn't exists in my site and they are not in sitemap.xml either...

Days ago I started to receive some emails coming from my forms and discovered is a new attack abusing open relays (some says). I wonder if it has something to do and someone experienced something similar.

But I wonder what effect has on Google crawling those "docs"?