Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 9ad38c251b929eda…

MALICIOUS

Office (OLE) / .XLSX

71.4 KB Created: 2022-01-20 19:00:43 Authoring application: Microsoft Excel
MD5: 5a6ac3a9701c7c5323d774b4dda7cc4f SHA-1: 40e7a5e7b6aebc9d738c63e618444f70531df834 SHA-256: 9ad38c251b929edaf974d16b81d02e8b87ca16da14c4aa4eea44df09aa210c69
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, indicating a known Emotet variant. Static analysis revealed the presence of Excel 4.0 macros, specifically an Auto_Open defined name, which is a common technique for initial execution. This macro sheet is likely responsible for downloading and executing a second-stage payload, consistent with Emotet's 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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