If author does not specify the details, just add a line saying something like: "Icon (photo, music, whatever) credit: John Doe, www.example.com" to your about page.
If you want to help the author a bit more, especially on the web, link to the specific page and provide a description, e.g.: "[Yellow Monkey Icon] (links to the icon page), (c)/by John Doe, used under a Creative Commons Attribution license". This helps with SEO.
If you're making a derivative work, say so.
At least that's what I suggest for my CC-BY works.
This is certainly the sensible way. But with legal contracts it's not enough to be sensible. The author is supposed to specify. The times I've contacted authors to ask about their desired attribution they've never contacted me back (only about half-a-dozen times now).
If author does not specify the details, just add a line saying something like: "Icon (photo, music, whatever) credit: John Doe, www.example.com" to your about page.
If you want to help the author a bit more, especially on the web, link to the specific page and provide a description, e.g.: "[Yellow Monkey Icon] (links to the icon page), (c)/by John Doe, used under a Creative Commons Attribution license". This helps with SEO.
If you're making a derivative work, say so.
At least that's what I suggest for my CC-BY works.