Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 a28072bc1ac780d3…

MALICIOUS

Office (OLE) / .XLSX

142.8 KB Created: 2022-01-26 02:21:30 Authoring application: Microsoft Excel
MD5: a7d0a2edb8ce0b4518c879770a2a1104 SHA-1: 3dc9a9d3404de8041914e8aa0790f7a52c1f66c4 SHA-256: a28072bc1ac780d3602bcebc97c6df14b396d531fbcb5f40642872f7cf7f8f12
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 macro, which is a known technique for executing malicious code. ClamAV detection explicitly identifies it as an Emotet downloader. The macro uses dangerous formula APIs, including the RUN function, indicating it's designed to execute an external 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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