Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 a690bda4ad1bf1c1…

MALICIOUS

Office (OLE) / .XLSX

69.5 KB Created: 2022-01-20 19:00:43 Authoring application: Microsoft Excel
MD5: 9e70b2c0cd92a0127269d2750afa6e5a SHA-1: e35081a7ebf943f49fcc4cf23442daf14dd47614 SHA-256: a690bda4ad1bf1c1685a7d8a18d09327284fb0d9e74371f97e7c7ee7c6159efa
140 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file is identified as malicious by ClamAV with the signature Doc.Downloader.EmotetExcel01220-9937164-0. Static analysis revealed the presence of Excel 4.0 macros, specifically an Auto_Open defined name, which is a common technique for Emotet to execute its initial payload. The macro sheet itself contains obfuscated code, typical of Emotet downloaders, designed to run automatically when the spreadsheet is opened.

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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