Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 c3ffc41a5585e7a6…

MALICIOUS

Office (OLE) / .XLSX

142.8 KB Created: 2022-01-26 02:21:30 Authoring application: Microsoft Excel
MD5: 7f7b2f04446b25ddf86aa9d19ff354f4 SHA-1: 6f8ba29aeeabb76ba0ceead204546c97136536e3 SHA-256: c3ffc41a5585e7a66e855fd8243ba5f6fa2f3abdf42ae66d8abd6b954259d8e8
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a known technique for executing malicious code. ClamAV identifies the file as 'Xls.Downloader.Emotet', strongly suggesting Emotet family involvement. The macro's use of dangerous formula APIs like RUN indicates it's designed to download and execute a second-stage payload.

Heuristics 4

  • 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.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • ClamAV: Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0
  • 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
46284ea41c691066b9fe85a87bc7e9bfc77336182ea3b4ed700574b0c8cd3189		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3141 bytes

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