The intermediate .crt file can be in PEM or DER format; it is PEM format if viewable using a text editor. See Certificate File Naming and File Formats for more information.
If other formats are required OpenSSL can be used:
To convert PEM to DER:
openssl x509 -outform der -in intermediate.crt -out intermediate.der
To convert DER to PEM:
openssl x509 -inform der -in intermediate.crt -out intermediate.pem
