Uploading images with wordpress

When I was trying to upload the dilber image while writing this post, I was surprised to find out that the image was not getting uploaded and worpress throwing back HTTP error.

After googling around, I figured out the similar problem here. Though in my case .htaccess file was blank (in root www directory of wordpress). I added following lines to the file and uploaded.

 <IfModule mod_security.c>
<Files async-upload.php>
SecFilterEngine Off
SecFilterScanPOST Off

This solved the problem for now. Does anyone have detailed idea on this issue?