Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 1aa1e797bd106f28…

MALICIOUS

Office (OLE) / .XLSX

71.4 KB Created: 2022-01-20 19:00:43 Authoring application: Microsoft Excel
MD5: 1a59b73480501ddead0d4fcff73dca23 SHA-1: c5e0aac4105036450c2f42e73d239528de2a6569 SHA-256: 1aa1e797bd106f28bc73e4a09bd4d3eb7a13943ef42f06bda76c41fbca54d0be
140 Risk Score

Malware Insights

Emotet · confidence 95%

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

The critical heuristic OLE_XLM_AUTOOPEN_DEFINEDNAME indicates the presence of an Excel 4.0 Auto_Open macro, which is a common technique for initial execution. ClamAV detection further confirms its malicious nature, identifying it as Emotet. The macro sheet likely contains code to download and execute a second-stage 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.EmotetExcel01220-9937164-0 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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