Emotet — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 91fd68ce0a1bd525…

MALICIOUS

Office (OLE) / .XLS

264.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-03-25
MD5: 36862151101d37724167749d0acfffe3 SHA-1: 642c701e81cf1cd50d72438c958e029dd60d3b95 SHA-256: 91fd68ce0a1bd525c892dabb6754f2099669e7f6ae2aeb486efbf6e20dbb2d5a
262 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open macro that utilizes dangerous functions like RUN. The macros reconstruct and embed three URLs which are likely used to download a second-stage payload. ClamAV detection confirms this as an Emotet downloader variant.

Heuristics 6

  • 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.
  • URL reconstructed from XLM cell array (3 URLs) critical OLE_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across the BIFF8 Shared String Table (one quoted-char SST entry concatenated with & at runtime) or across individual numeric cells (one ASCII charcode per cell). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF8 record stream and decoding SST entries plus LABELSST/RK/NUMBER cells.
  • ClamAV: Xls.Downloader.Emotet-MSOLE2-af43432fbcb8603c-9980047-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-MSOLE2-af43432fbcb8603c-9980047-0
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://urbizstartup.com/cyL5fzZgbH8/Hnfho.png
    • https://aryanglobalschool.in/L2Xe4PaSpwYi/Hnfho.png
    • https://gurunanakinternational.com/7ZflR1ubibNT/Hnfho.png

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
b335eaf779e69cee435a99d0ade92534fcbe861363b323f3b3bcbc16be1ec4c8		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6832 bytes

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