Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 b3973d991b4f3e38…

MALICIOUS

Office (OLE) / .XLSX

142.9 KB Created: 2022-01-19 09:31:16 Authoring application: Microsoft Excel
MD5: 9db324dc873d1b9f5d96ca9f242ccbce SHA-1: 9219af2794c0c4c3f3ec48cb1067db541372fdd5 SHA-256: b3973d991b4f3e3870404c40bf59257bd40f4207f10dd5a6c34a8d4e29e0f7ea
140 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a strong indicator of malicious intent. ClamAV detection further confirms this, identifying it as 'Doc.Downloader.EmotetExcel01220-9936774-0'. The presence of an Auto_Open macro suggests the file is designed to automatically execute code upon opening, likely to download and run a secondary payload, consistent with Emotet's typical behavior.

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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