Emotet — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 ac7504cc24040a59…

MALICIOUS

Office (OLE) / .XLSX

143.0 KB Created: 2022-01-26 02:21:30 Authoring application: Microsoft Excel
MD5: c64c2b29b9e60ef780227668ac8539b8 SHA-1: fbc3cfd3e68d691de6635ffb08df2a187b5a1501 SHA-256: ac7504cc24040a59e05bb1040f6d6f09c8b15f07cc9f32c884f64805504020c0
200 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The ClamAV detection explicitly names Emotet, and the presence of Auto_Open with dangerous formula APIs like RUN indicates the macro is designed to execute arbitrary code. This functionality is consistent with Emotet's typical behavior of downloading and executing further malicious payloads.

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