Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 a9e494ace3fac3df…

MALICIOUS

Office (OLE) / .XLSX

143.3 KB Created: 2022-01-26 02:21:30 Authoring application: Microsoft Excel
MD5: 8df5166e14c8521339bca4018dd6ea4a SHA-1: 222843c57fec58c8ffad0570c6342e34ac4b2ef3 SHA-256: a9e494ace3fac3df054f1c08a88de3e6380ba8a8f33f6366d28e52fca550fbd2
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry point, specifically using the RUN function, which is a strong indicator of malicious intent. ClamAV detection further confirms this, identifying the file as 'Xls.Downloader.Emotet-bd646319c2d29cd6-9951195-0'. The Auto_Open macro is designed to execute arbitrary code, likely to download and execute a second-stage payload, consistent with Emotet's typical behavior.

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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