Joomla Media Manager image upload fail

One of my websites, which uses Joomla as CMS got hacked as I had not paid attention to securing the site properly. After this I did go through the site carefully trying to remove any possible loopholes.

Recently I realized that Uploading images through Media Manager or any other means were failing to upload. I tried various things but nothing was helping. I am listing some of them here:

1. Checking the Directory permissions. Even tried changing the unsafe mode of 777 to all the relevant directory. Did not help.

2. Tried disabling Flash based uploader – did not  help.

What it did was to give an error message of following kind:

JFile::read: Unable to open file: ”
Warning: Failed to move file!
Error. Unable to upload file.

3. I followed up on this and eventually found that If I do not use the “open_basedir” feature in php.ini to make it more secure by commenting it out in php,ini file, it works fine.

;open_basedir = /home/www

4. As of now, I do not understand why this happened and would like to understand if I can still use this feature to keep site safer.