is that necessary to use "base64_decode" function
 

is that necessary to use "base64_decode" function
becouse I want to but it in php.ini disable_function

and this function found on this file

PHP Code:
attachment.php:290: $filedata = base64_decode('R0lGODlhAQABAIAAAMDAwAAAACH5BAEAAAAALAAAAAABAAEAA AICRAEAOw==');
cron.php:44:$filedata = base64_decode('R0lGODlhAQABAIAAAMDAwAAAACH5BAEAAAAALAAAAAABAAEAA AICRAEAOw==');
includes/functions.php:2244: return ($decode ? base64_decode($return) : $return);

and when I disable this function its give me base64_decode is disable for security reason

I want to disable this function because some shell file decode them files to base64
my vbulletin version 3.8.4 patch level 1