Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 6f95d343a882d6e8…

MALICIOUS

Office (OLE) / .XLSX

69.8 KB Created: 2022-01-20 19:00:43 Authoring application: Microsoft Excel
MD5: b54682c94a61e6f17ce0990d8f996021 SHA-1: f9ae7ea99c3caa78df9d67cb954758e84259f39f SHA-256: 6f95d343a882d6e800379be638a48804dfc956537ffcc06361e1f57fa2938808
140 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file is identified as malicious by ClamAV with the signature Doc.Downloader.EmotetExcel01220-9937164-0, strongly suggesting an Emotet family infection. Critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry, which are designed to execute automatically when the workbook is opened. This mechanism is commonly used 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.EmotetExcel01220-9937164-0 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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