Symantec SSL Trial Certificate issues certificates without validation that the domain is owned by the one requesting the certificate. Doesn't this make it easy to do a man in the middle attack against any websites?
The SSL certificate issued using this process is not trusted by default by any software and thus cannot do any harm as long as the software is doing proper validation of certificates. And if the software is not doing proper validation there is no hope for this software anyway, i.e. you don't need this trial certificate but can create your own.
From the documentation:
In order to test the use of a Symantec SSL Trial certificate, you must install a special Symantec Trial Intermediate and Symantec Trial Root CA on the server. The Trial Root must also be installed in each browser that will be used during the testing phase. This is a special step that Symantec has implemented to prevent fraudulent use of trial certificates. When purchasing a production SSL certificate, these additional steps are not necessary.