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

Static analysis result for SHA-256 d1332bf8ec90093d…

MALICIOUS

Office (OOXML) / .XLSX

84.5 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: d8ee4cf24fddb2b8221533147b1c357a SHA-1: e7240bcf2c14845d3e74764c0c5108e3bc23d5d8 SHA-256: d1332bf8ec90093d975ddcd294873299adff4a85c10a5491f1b2fc19b98eab5c
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an Excel file containing a macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The embedded Excel 4.0 macro appears to be attempting to write a file to disk at the path 'C:\ProgramData\excel.rtf'. This suggests the document is designed to download and execute a secondary payload.

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
b04899e65776b47235e8617523da215cd82103d8c6e85f41660551fa4d358ec1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 95926 bytes

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