pass BP guid and attribute id in below FM and get all details of attached BP attributes
CRM_MKTBP_READ_BP_DATA
Also find some helpful table related to BP attributes:
INOB: Object ID, BP Number
KSSK: Object ID, Attribute set ID
CABN: Attribute ID and name
CAWN: Attribute name and values
AUSP: BP GUID, Attribute Name, Value, Object ID
KLAH: Attribute Set Name, ID
see scn question : https://scn.sap.com/thread/1350746
Spencer