Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 b280c76e8465a55f…

MALICIOUS

Office (OOXML) / .XLSX

61.1 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: b1140cdda01d03eac0e951289c1248d5 SHA-1: 90ba28df251c71bd52cc64366962a3f60e18b0d0 SHA-256: b280c76e8465a55f574a77d505deaf65bd15f0c895b59b87d9679b2c0626cfd5
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, which is a known method for executing arbitrary commands. The macro sheet contains strings that appear to construct a path to 'C:\ProgramData\excel.rtf', suggesting a potential payload or dropped file. This indicates a likely attack pattern of macro-based execution for initial payload delivery.

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.

FilenameKindSourceSize
xlm_sheet_00.bin
4e21f8ec3628920754467cc395ee5184191ec6368db3b55422867289b81fc2af		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 155253 bytes

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