Office (OOXML) / .XLSX malware analysis — malicious · dafa9bfb612f85bf

MALICIOUS

Office (OOXML) / .XLSX

87.5 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: 9426a4406d061b4ebebde6ea41cd9067 SHA-1: 590553e4a22575c5ca1494e7e983c1db9051a21d SHA-256: dafa9bfb612f85bf149ce6807ac008081c124326c85752864682e705e044d0b4

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of an Excel 4.0 macro sheet. Analysis of the macro content reveals a command that appears to be constructing a path to a directory within ProgramData, likely for staging or executing a downloaded payload. The macro's obfuscated nature and the presence of a suspicious path suggest a downloader or initial access mechanism.

Heuristics 1

Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET

Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `9f5b66b18acd6b012990be94c7b8c0032870ebde76cc13fe371b69f276022060`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4016 bytes

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