File operations which may access external resources are executed

Hi,

Our smart scanner scanned and reported some messages..

"File operations which may access external resources(e.g. malicious third-party websites) are executed.
System commands are executed on the server.
Files are opened/or modified.
Email is sent."

And it is showing some file names which have been affected. (system/libraries/Upload.php, system/libraries/Email.php, system/libraries/image_lib.php).


How to solve this issue..? Could you please help me?