Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 9929490ee7571f70…

MALICIOUS

Office (OLE) / .XLSX

142.1 KB Created: 2022-01-26 02:21:30 Authoring application: Microsoft Excel
MD5: 52826053a4a58665b76afcd0c0fb398e SHA-1: 1594fe114d25322d7e319ce0ab31f66e853d2724 SHA-256: 9929490ee7571f70f491565c6bae49a1f585ca716f29ffe4781896240e754c6f
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open function, specifically noting the use of dangerous formula APIs like RUN. ClamAV detection confirms this as Emotet. The macro sheet is likely designed to download and execute a second-stage payload, leveraging the Auto_Open entry point to run automatically when the document is opened. The document body is a generic time card, a common lure for malicious documents.

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