Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 0d66a9fb60368fe3…

MALICIOUS

Office (OOXML) / .XLSM

20.9 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-17
MD5: 5d76332af4a3caefdefc696342d41d0c SHA-1: 2f8339681dd8e1f085ce2751bd5ca1262d9c30c2 SHA-256: 0d66a9fb60368fe3671f2219bcf80c40574b061f3b1268b807d93fcecbd7a3af
250 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an XLSM file containing Excel 4.0 macros, identified by critical heuristics. These macros utilize dangerous functions like FORMULA to construct URLs and download payloads. The reconstructed URL is "https://canismallorca.es/wp-admin/OTyeYrx9C9BvYvVb3/", and the script attempts to execute "regsvr32.exe" with a DLL named "kytk.dll" from the Windows SysWow64 directory. This behavior is consistent with Emotet's known download and execution tactics.

Heuristics 6

  • Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET
    Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks.
  • Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME
    Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
  • Dangerous XLM formula APIs: FORMULA critical OOXML_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet uses formula APIs that call directly into Win32 (=CALL/=EXEC/=REGISTER/=FORMULA). These are the primitives used to download payloads, write files, and start processes from an XLM macro without invoking VBA.
  • ClamAV: Xls.Downloader.Emotet03220-9941789-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03220-9941789-0
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 4 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • 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://canismallorca.es/wp-admin/OTyeYrx9C9BvYvVb3/
    • http://www.cafe-kwebbel.nl/layouts/3Wkev/
    • http://borbajardinagem.com.br/erros/vlB3f6XpsZG/
    • http://belleile-do.fr/diapo-ile/EeBHyfGoKYACY/
    • http://capslock.co.za/wp-includes/LMngUUTuanBofr5zK/
    • http://bkps.ac.th/b91-std63/Ixv52m8gu4aaUiyb/
    • http://www.best-design.gr/_errorpages/9wCa7GLI0cl6nM/
    • http://schemas.openxmlformats.org/spreadsheetml/2006/main
    • http://schemas.microsoft.com/office/excel/2006/main
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac
    • http://schemas.microsoft.com/office/spreadsheetml/2014/revision
    • http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision3
    • http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
bd1141b96e73c592d43d300feb4a2bed92034dffba7d5e49bf95a81f1348fbbc		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 4144 bytes

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