delivered malicious documents with the XLSX extension typically used by OpenXML documents but the file itself was actually an OLE (XLS) document.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request. ### Instruction: List the MITRE techniques contained in the text. ### Input: delivered malicious documents with the XLSX extension typically used by OpenXML documents but the file itself was actually an OLE (XLS) document. ### Response: T1221.