Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 dbd90a27931574ef…

MALICIOUS

Office (OOXML) / .XLSX

238.4 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-15
MD5: 84ed8547745a9e828fb9b590c8e1985a SHA-1: edbc1a5c91d7168f09a09edb7eacfb6af394fa89 SHA-256: dbd90a27931574efb62618320be8936875066ef290f3e85cabafd536334bb6c1
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-enabled document, a common delivery mechanism for Emotet. The presence of multiple XLM macro sheets and the ClamAV detection signature 'Xls.Downloader.Emotet-OOXML_XL-af43432fbcb8603c-9980048-0' strongly indicate Emotet activity. The macros are likely designed to download and execute a second-stage payload.

Heuristics 3

  • Excel 4.0 macro sheet (3 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
2eee5ae961fe5d65f35cf8570602a23d6ff455536901fc8d2a2296dc48ce0fed		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin 2127 bytes
xlm_sheet_01.bin
76bb729a3fef1962dba3c4d4608bc67767a415d3068cfaefbab6dc04307f5716		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 428 bytes
xlm_sheet_02.bin
e107436a5f0bb0a25f454c2c3756c9b0d1befa58088a66751c1bc69dc47f10ec		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.bin 428 bytes

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