Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 788c05502ef517d0…

MALICIOUS

Office (OLE) / .XLSX

95.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-07-12
MD5: 31ad4b373a6bc92a490e967b76a736a6 SHA-1: 732267658a0e6c0a87e3f016842e422ba70524a9 SHA-256: 788c05502ef517d0a5cddff6d686d303e233b8ab54cbadea06482363a740bf31
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The sample is an Excel file containing Excel 4.0 macros, specifically an Auto_Open macro that uses dangerous functions like RUN. This indicates an attempt to execute arbitrary code. ClamAV detection confirms this as Emotet, a known downloader family. The presence of an Auto_Open macro strongly suggests it's intended to be delivered as a spearphishing attachment to trick users into opening it and triggering the malicious macro.

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-ea81817e7f807ab1-9952142-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-ea81817e7f807ab1-9952142-0
  • 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
cc3e5aac3d609a0dff36aafb62d01902df6b63b8c5574276ba1d72203d971bec		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8169 bytes

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