Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 cfb445f5bf6f9e73…

MALICIOUS

Office (OLE) / .XLSX

141.1 KB Created: 2022-01-19 09:31:16 Authoring application: Microsoft Excel
MD5: 186ec3f1fde5ee03ed49b64eda3490e4 SHA-1: 248acbab68fab95a02652a59186a8269f56a7b34 SHA-256: cfb445f5bf6f9e73f79134ad0e65b09c75066fded4ba099918cd060e999ae52f
140 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file is identified as malicious by ClamAV with the signature 'Doc.Downloader.EmotetExcel01220-9936774-0', strongly suggesting an Emotet family infection. Critical heuristics indicate the presence of Excel 4.0 macros, specifically an 'Auto_Open' entry, which is a common delivery mechanism for Emotet. These macros are designed to execute automatically when the workbook is opened, likely initiating the download of a further stage payload.

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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