See posts #4 and #5 in this thread.
The only permanent solution is to upgrade. SCO 5.0.6 is essentially free, as it can be installed using your existing serial number and activation key (with the exception of very early serial numbers issued by Compaq/HP.)
If you expect to continue using the application for the foreseeable future, then upgrading to 5.0.7, or 6.0.0 should be considered.
Both have SSH and relatively new versions of php, apache, bind etc. The major difference is that 5.0.7 uses the Unix System 5 release 3.2 kernel with the HTFS file system and 6.0.0 uses the System 5 release 4.0 kernel with vxfs.
You can do an update install of 5.0.7, but 6.0.0 requires a fresh install, and typically a couple of days effort.
One caveat. Software in 'custom' format that will install on 5.0.2 will not install on 5.0.5 and newer. You can, however, tar the software from the old system are restore it to the new system. Only the format of the custom package changed, not the ability of the system to run the software.