Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 4dfb7a9f41436ab5…

MALICIOUS

Office (OOXML) / .XLSX

202.4 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 9dadbfe217a7f377e0ca1bfa97919925 SHA-1: 42e27199e9fa3a9d0626d06fb7d12381e26a2119 SHA-256: 4dfb7a9f41436ab5d642241ed14607ea304364631358f143b708011c1f90d63d
180 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample is identified as an Excel 4.0 macro sheet embedded within an XLSX file, a known technique for delivering malware. The ClamAV detection explicitly names 'Emotet' and indicates a downloader functionality. The embedded XLM macros are likely responsible for fetching and executing a secondary payload, consistent with Emotet's typical behavior.

Heuristics 3

  • 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.
  • XLSB international XLM macro sheet hidden in .xlsx critical OOXML_XLSB_INTL_MACROSHEET_IN_XLSX
    OOXML package is named .xlsx but contains XLSB workbook parts and an international Excel 4.0 macro sheet. This hides XLM macro execution from scanners that trust the extension or only inspect XML worksheet parts. The technique is macro execution, not a document-parser CVE.
  • ClamAV: Xls.Downloader.Emotet-OOXML_XL-af43432fbcb8603c-9980048-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-OOXML_XL-af43432fbcb8603c-9980048-0

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
a2d4f9910b57a5ea9f0f60a8236ec6d4a482a9e70e10e8d1d85ef6205b8ccd09		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin 1799 bytes

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