Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 a6e9fab4c53c4a03…

MALICIOUS

Office (OLE) / .XLSX

142.8 KB Created: 2022-01-19 09:31:16 Authoring application: Microsoft Excel
MD5: 5299f2db2ada33135a7f5ecdb296f7af SHA-1: b21d2c01cb42cadfe0257f025cd326aabd59ec76 SHA-256: a6e9fab4c53c4a0357ceb77a92e8e87510a45387ec973da01ea3a3f4d356ac7d
140 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file contains critical heuristic firings indicating the presence of Excel 4.0 macros with an Auto_Open entry point, a known technique for Emotet. ClamAV also specifically detected it as 'Doc.Downloader.EmotetExcel01220'. The macro sheet appears to be designed to execute automatically upon opening, suggesting it's intended to download and execute a second-stage payload. The document body content is benign, serving as a lure.

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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