Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 ad583c4b877a37db…

MALICIOUS

Office (OLE) / .XLSX

71.0 KB Created: 2022-01-20 19:00:43 Authoring application: Microsoft Excel
MD5: 05de74dfc08dff10864dd24bf1372cf7 SHA-1: dfe92a0fda7dca811c6ce5b20d7f035e2cf97a00 SHA-256: ad583c4b877a37dbf913c275e1bce335b8e73817d61039a2a510e28f325d3e6c
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 Excel 4.0 macros with an Auto_Open entry, which is a common execution vector for Emotet. ClamAV detection further confirms this classification. The macro sheet itself is truncated, but the presence of the Auto_Open entry strongly suggests the intent to execute malicious code upon opening the file, consistent with Emotet's typical delivery mechanism.

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.EmotetExcel01220-9937164-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.EmotetExcel01220-9937164-0
  • 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
7f1f89a8b36a750dced08313a4e4f056192a6eac7194357c673dbbd2670a1a18		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 4219 bytes

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