DotNetNuke Input string was not in a correct format

Yesterday all my my DNN 7.3.4 portals show an  a generic error message and didn't show any content.
I was able to login as superuser and could check that the real error was "DotNetNuke Input string was not in a correct format".
Every module gave this error.
I spent a day to found the couse to this problem, I checked a lot of blog about this error without success.
Finally I found that everything was coused by a malware attack, probably due to a DNN vulnerability.
I dont' know how, but table ModuleSettings was updated and value on column SettingValue was changed joining the oringinal value to a html string, take a look to the picture:


To repair the table I used the following sql script:
update [ModuleSettings] set SettingValue=case when CHARINDEX('<',SettingValue)>1 then SUBSTRING(SettingValue,1,CHARINDEX('<',SettingValue)-1) else '' end

after this I had to manually delete the cache removing files in [Portal]/Cache/Pages and restart the application.

This make me think that a vulnerability exists on DNN 7.3.4, hope this help to fix it.