Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 353ddb1ede173839…

MALICIOUS

Office (OLE) / .XLSX

142.1 KB Created: 2022-01-26 02:21:30 Authoring application: Microsoft Excel
MD5: ae5b6e169c987672e83e47ab6c0c6900 SHA-1: 199ddebf75b7337da1966f8c133cf0166d162093 SHA-256: 353ddb1ede17383924fa78ecf533557d2bf9b35db67765f2c52384f07cdb5c76
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for Emotet. The critical heuristics indicate the presence of dangerous formula APIs like RUN within the Auto_Open macro. ClamAV detection further confirms this as Emotet. The macro is 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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