Working through an upgrade / migration on a client site and needed to be able to identify custom reports created within the ConfigMgr 2012 reporting structure.
The following query will provide that information, change the DOMAIN below to match your domain name. Run from SQL Server Management Studio.
SELECT c.Path ,c.Name ,u.UserName ,c.CreationDate ,c.ModifiedDate ,c.Description ,c.Hidden FROM [ReportServer].[dbo].[Catalog] c INNER JOIN [ReportServer].[dbo].[users] u ON u.UserID = c.ModifiedByID where UserName LIKE 'DOMAIN%'