Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 2e7c6b9eef00daba…

MALICIOUS

Office (OOXML) / .XLSX

135.6 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: b80c1aa361cb9d0fe2d98e505334f9bf SHA-1: a02d5e37dea04791776087ece3a6d665e51dcf64 SHA-256: 2e7c6b9eef00daba7e9bdb8355cdb71278645579f64a892c79e0d57892766681
180 Risk Score

Malware Insights

Emotet · confidence 95%

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

The sample is identified as malicious by ClamAV with the signature 'Xls.Downloader.Emotet-OOXML_XL-af43432fbcb8603c-9980048-0'. Heuristics confirm the presence of Excel 4.0 macro sheets within an XLSX file, a common delivery method for Emotet. The extracted macro sheet content, though truncated, suggests a downloader functionality, likely responsible for fetching and executing further malicious code.

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
e211bc8384b61ceb3c2f952e9869fef2f7cc488f3128253772792a2ecd7a5adc		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin 1823 bytes

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