There is a file "core" without extension and it is updated regularly. it size more than 100MB. this is happens recently.

Where is that? There is no file named "core" in Zenphoto.

it is in root.
i downloaded and opened it in text viewers. it is not readable.

here i am pasting the sample.
`

• @return int

*/

/**

• Returns true if the image is landscape-oriented (width is greater than height)

`
junk characters are not able to paste.

As said there is no such file and that does not belong into the root there. There is apparently something completly wrong on your site/server/install if that file even is updated and grows to 100+ mb. The only "files" Zenphoto kind of updates in the root are either the htaccess or the robots.txts files and that only on running setup. Other files Zenphoto updates are the logs withing zp-data.

Sorry to say but you might have been hacked again or did not clean out successfully (you were amongst the ones affected if I recall right but it might be a different hack of course).

Btw, what you posted is a function comment from the function is_landscape() located in /zp-core/template-functions.php on line 2357.

I've seen files a few times that match your description, and they were malicious shell scripts. I realize this topic is a month old, but if you've got one of these sitting on your server, someone else has way too much access to that server.