Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 c74b76fc747a530f…

MALICIOUS

Office (OLE) / .XLSX

142.9 KB Created: 2022-01-19 09:31:16 Authoring application: Microsoft Excel
MD5: dc3940863db7ebffc476296f74d595ac SHA-1: 0d020f5ada48d4d6c04b0201c9b7de6a08f3f863 SHA-256: c74b76fc747a530f581851b5269d66e5aa5a4f99a8136cf93b50a4e2fbd864e9
140 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file contains critical heuristic firings indicating the presence of Excel 4.0 macros with an Auto_Open entry, a known technique for Emotet. ClamAV also specifically detected it as 'Doc.Downloader.EmotetExcel01220-9936774-0'. The macro sheet appears to be designed to execute automatically when the workbook is opened, typical for a downloader stage.

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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