Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 4083be0a459f2f9a…

MALICIOUS

Office (OLE) / .XLSX

141.5 KB Created: 2022-01-19 09:31:16 Authoring application: Microsoft Excel
MD5: ea2d920e1eae6dc4d8470aebebe0f30e SHA-1: 6592fb067a3cd5062239e4fe99fac793dfb10370 SHA-256: 4083be0a459f2f9aaa168e5b6c5ecdac601246a50038b458ed3cb1a988dbf700
140 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_AUTOOPEN_DEFINEDNAME indicate the presence of an Excel 4.0 Auto_Open macro. ClamAV detection further confirms this as 'Doc.Downloader.EmotetExcel01220-9936774-0', a known Emotet downloader variant. The macro sheet contains an Auto_Open defined name, suggesting it's designed to execute automatically upon opening the spreadsheet, likely to download and execute a secondary payload.

Heuristics 3

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • ClamAV: Doc.Downloader.EmotetExcel01220-9936774-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.EmotetExcel01220-9936774-0
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
592af8991900f2f7058dc7ea90a33320ae293c7e541db4222a7b7f9c04f59d96		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8469 bytes

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