Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 81cc6a5de9853b4f…

MALICIOUS

Office (OLE) / .XLSX

115.6 KB Created: 2022-01-24 14:50:55 Authoring application: Microsoft Excel
MD5: 4666c14cad044960841e1734d2267df8 SHA-1: 4da75c522780f3331b4dc30f872578ffbba0ec25 SHA-256: 81cc6a5de9853b4fb1f3fb911ce8d7d8b2e91de48ee9618f58a9f4b2a6139660
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The sample contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code. ClamAV detection explicitly identifies this as an Emotet downloader. The presence of the Auto_Open macro and the dangerous formula API 'RUN' strongly suggests the macro is designed to download and execute a secondary 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
f65423032a2492710482664c048191ebe835ee4ace2752f1b0fa6e40d416cdf9
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 4885 bytes