An updated Visual Studio 2008 C Runtime (version 9.0.30729.7523) ships with ArcGIS 10.2 and includes a security fix described in Microsoft KB2607389, which changes the behavior of the Microsoft Foundation CDatabase class when working with database passwords and causes ODBC connections to appear broken for third-party software.
The Microsoft security fix encrypts database passwords stored in memory and causes the CDatabase::GetConnect() method to return an empty string. If ArcGIS 10.2 is installed on machines running third-party software applications which use CDatabase::GetConnect(), access to ODBC connections may appear broken.
Microsoft has acknowledged the problem and identified the affected component as the MFC CDatabase class. Further details are provided in KB2915724.