Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 d1f21a0cf4a01b1e…

MALICIOUS

Office (OOXML) / .XLSX

251.0 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-02-28
MD5: c9b63a8602133bed4b0249ea1ac3b8c4 SHA-1: c57be3967a90b992803a242f7695d2f9333337d7 SHA-256: d1f21a0cf4a01b1e75d0d00c0675038cc9e0ead5677e888ec965865cb4090ada
180 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic

The sample is identified as malicious by ClamAV with the signature 'Xls.Downloader.Emotet-OOXML_XL-af43432fbcb8603c-9980048-0', indicating it is an Emotet downloader. Static analysis reveals the presence of Excel 4.0 macro sheets, which are commonly used to execute malicious code. The macros are likely responsible for downloading and executing a secondary payload, consistent with Emotet's typical behavior.

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
e7eddde921470c58ab0a38d588bb974478d715c8e1386d63b264345f8d70b9f4		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin 2327 bytes
xlm_sheet_01.bin
06e05c87d9f0de6cf34cd0bc473cb2e5947f26c9ccf4d177fd7730cb74b9eb32		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 428 bytes
xlm_sheet_02.bin
939824154a28b8cafaa71e7f1d75c07e164d391f2fee63b982183b711e8f8093		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.bin 428 bytes

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