Emotet — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 66ae76229e7bf683…

MALICIOUS

Office (OLE) / .XLS

252.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel
MD5: 4083f52bffc3e3e33e3e6c1f724d3c5a SHA-1: 62715bd8fe14fa8ef7251bfa4810a453a1146318 SHA-256: 66ae76229e7bf683e24ad78e8d2ab39ae9b6e36abb18abc34ce1def8e6c4c6e1
262 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 macro, which is a known technique for executing malicious code. The macros reconstruct and attempt to download payloads from three distinct URLs. ClamAV detection and the presence of these indicators strongly suggest Emotet downloader activity.

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://orthomay.com.br/GD7A3PSD4zc/tw.html
    • https://quebradadigital.com.br/ag2DVqIM/w.html
    • https://mustafakhafimsp.af/UnE5kOnX/tw.html

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
7f7c80d5caeaf0a3da27c73e59984c758228750205ac010ee0d8c2e576fbb6bc		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 11375 bytes

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