Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 f8746c0e7d492357…

MALICIOUS

Office (OLE) / .XLSX

141.3 KB Created: 2022-01-19 09:31:16 Authoring application: Microsoft Excel
MD5: c49f3c2af3a254c4ff41d43c29ee3b8d SHA-1: a7db7d7a9179a63426bd4712a36ee9016f8ad5c5 SHA-256: f8746c0e7d492357a8f30e424870c4fce49699d165260610a62360668541035a
140 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file is identified as malicious by ClamAV with the signature Doc.Downloader.EmotetExcel01220-9936774-0, indicating it is a known Emotet downloader. Critical heuristics confirm the presence of Excel 4.0 macros with an Auto_Open entry, which are commonly used to execute malicious code. The macro sheet contains references to sheet names like 'Blood Pressure Data', suggesting a lure to trick users into enabling macros. The primary function of the Excel 4.0 macro is to execute arbitrary code, likely to download and run a secondary 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