Struggling to find a way to extract data between 2 strings

[sourabhkrishna]

Sample Data:

**** GUID1 START ****
data1
data2
**** GUID1 END ****

**** GUID2 START ****
data1
data2
data3
**** GUID2 END ****

**** GUID3 START ****
data1
data2

**** GUID4 START ****
data1
data2
data3
data4
**** GUID4 END ****

The above is how my input data in txt file format is generated. How do I extract data between start and end Guids and ignore all guid that do not have an end mentioned in the data.