The Validate Rowset task was added in version 5.4.1 and then enhanced in Version 5.5.2.
The Validate RowSet task allows you to validate the data contained in a RowSet that was generated by tasks that read the contents of a file or database (for example, SQL or Read CSV tasks). This is useful for identifying problems with data before it is used in another task, such as inserting it into a database or translating it to another file format.
The Validate RowSet task can be used to determine if the RowSet contains a minimum or maximum amount of rows in the RowSet. The task can additionally determine if the expected number of columns are present, can verify the data in the column meets specified conditions, or the data is of the correct data type and format.
In your situation, you would read the file and save to an output rowset. Then using the Validate Rowset Variable task, verify if a column has a certain value. This would be accomplished by using a substring expression. The online help for this task includes a very nice example.