Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 ab1cfc5403e7fd78…

MALICIOUS

Office (OLE) / .XLSX

141.5 KB Created: 2022-01-18 14:11:14 Authoring application: Microsoft Excel
MD5: 02f01d9bb88159fed4c1157a192d0631 SHA-1: 887d5d9bc8026f02d25ade0df50145ca70139761 SHA-256: ab1cfc5403e7fd780f3dade25696cc27faeb1bee71ec075940c364687c539e68
140 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 and an Auto_Open defined name, which is a common execution vector for Emotet. ClamAV also specifically identified this file as 'Doc.Downloader.EmotetExcel01220-9936774-0'. The macro sheet contains an Auto_Open entry, suggesting it's designed to run malicious code automatically when the spreadsheet is opened, likely 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
c355a4e8b51815f97cf3e202ab7d47ce16f5f701c419b0e7a11ef751a8ea709e		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 3661 bytes

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