There has been a recent WHMCS Exploit discovered . The WHMCS billing system developers are working on this bug. We also working on our portal site , portal.syslint.com . So it may take around 24 hours of down time for solving this issue.
In mean time if you need any help , please send an email to firstname.lastname@example.org .
The details of this exploit can be read from http://www.webhostingtalk.com/showthread.php?t=1314057
We are apologizing for this downtime in service.
Update : Whmcs has released a patch for this issue. So all installation clients are requested to upgrade to version 5.2.9 .