Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 23dc54d35406a09e…

MALICIOUS

Office (OLE) / .XLSX

141.7 KB Created: 2022-01-19 09:31:16 Authoring application: Microsoft Excel
MD5: 9d8ec17d41eb9bab197ba6dd191ef116 SHA-1: cb47850dd4619a02c400e69e0d9252db14cc371b SHA-256: 23dc54d35406a09e9c7ebc21aed24c81434f62784b5a94ff6b762b39008d3a05
140 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file is identified as malicious by ClamAV with the signature 'Doc.Downloader.EmotetExcel01220-9936774-0', indicating it's a known Emotet downloader variant. Critical heuristics confirm the presence of an Excel 4.0 macro sheet with an 'Auto_Open' entry, which is a common technique for executing malicious code upon opening the document. The macro sheet is likely designed to download and execute a second-stage payload.

Heuristics 3

  • 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.
  • ClamAV: Doc.Downloader.EmotetExcel01220-9936774-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.EmotetExcel01220-9936774-0
  • 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
592af8991900f2f7058dc7ea90a33320ae293c7e541db4222a7b7f9c04f59d96		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8469 bytes

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