Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 4627d88cb27d8855…

MALICIOUS

Office (OLE) / .XLSX

142.7 KB Created: 2022-01-19 09:31:16 Authoring application: Microsoft Excel
MD5: 70caf460cf0c000b71bd37cc9e8d3065 SHA-1: d5cf4d2edfc7466a0292cec8e435839ee139bd7d SHA-256: 4627d88cb27d885555625326c40717630dbfc7708869fdde4d0064f2d59e5bb4
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 an Excel 4.0 Auto_Open macro, a common technique for initial execution. ClamAV detection further confirms its malicious nature, identifying it as Emotet. The macro sheet contains references to sheet names and labels, but the core execution logic is not fully visible in the provided excerpt. The primary attack vector is likely a spearphishing attachment leveraging the Auto_Open macro to initiate a download chain.

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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