Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 29111d8e5e8306e7…

MALICIOUS

Office (OLE) / .XLSX

71.3 KB Created: 2022-01-20 19:00:43 Authoring application: Microsoft Excel
MD5: 3e1848e9589561d5605a85ecba0bbeea SHA-1: 5b7e2ca5ccb64cc6acd1671e10c050b5bc74d67d SHA-256: 29111d8e5e8306e76660db292e7232ab39e901955014eede21e912c931a09b5f
140 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1059.005 Visual Basic T1059.001 PowerShell

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry, a known technique for initial execution. ClamAV detection further confirms its malicious nature, specifically identifying it as an Emotet downloader. The macro sheet itself contains numerous string constants and references, but no directly executable commands or URLs were recovered from the truncated script listing. The primary attack vector is likely a macro-enabled document delivered via email.

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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