Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 43a573dc9dd0dc79…

MALICIOUS

Office (OLE) / .XLSX

142.0 KB Created: 2022-01-19 09:31:16 Authoring application: Microsoft Excel
MD5: 04b006830db46bac4dd4ef853791698c SHA-1: dac03147850b30ec401e7cd4e28171a2b6868899 SHA-256: 43a573dc9dd0dc79dcf228467e8e6820f4a4f8bf344660ea43eb11bb7b3c93f7
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.EmotetExcel01220-9936774-0', indicating it's a known Emotet downloader variant. Critical heuristics confirm the presence of Excel 4.0 macros with an Auto_Open entry, which is a common delivery mechanism for Emotet. The macro sheet is designed to execute code automatically when the workbook is opened, consistent with Emotet's behavior of downloading and executing further stages.

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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