Marcin Kijak

After installation you can find “Noindex by path” option in the main menu. This allows you to simply add relative paths 
you need to exclude from SERPs. Add a path (including slashes from begging and the end of the string) and save the 
changes. Since this plugin is called to be “simple” you can add only one path at once, but the process is smooth 
and easy.
Plugin will add “noindex” meta tag which is an instruction for search engines that this particular page should not be indexed. 
Technically it modifies wp_head tag.

Noindex by Path

Ask search engines not to index individual pages by a relative path - which means you can set every url no matter it is a page, category listing or an …

modernwebstudios

This plugin add meta tag noindex,nofolow to head of any attachment page().

MWS Noindex Attachment Pages

This plugin add meta tag noindex,nofolow to head of any attachment page().

Noindex by Path vs MWS Noindex Attachment Pages