Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 ab2adaf6d37b583f…

MALICIOUS

Office (OOXML) / .XLSX

103.0 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: d1907a6f1ce25f9701f62e0ff856de9b SHA-1: dd71ea3e4ccfc351e6397e0ffb1f080e042d0e2d SHA-256: ab2adaf6d37b583f270e16df799f9d44a0240139ff38cc1b206f382fc5529644
250 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1204.002 Malicious File T1059.005 Visual Basic T1218.011 Rundll32 T1105 Ingress Tool Transfer

The file contains Excel 4.0 macros, specifically using the dangerous FORMULA API to call Win32 functions. The macros construct URLs by concatenating strings, such as 'http://landorestates.com/wordpress/NELf96wr/', and then use 'rundll32.exe' to download and register a DLL ('wlw.ocx') from these URLs. This behavior is characteristic of Emotet downloaders, which are known to use macro-enabled documents to fetch and execute further stages of their payload.

Heuristics 6

  • Excel 4.0 macro sheet (3 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.EmotetRed02223-9938636-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.EmotetRed02223-9938636-0
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 6 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 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

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
5a62a357cb895c98dc30b4c4c5c056eac8ac1b92bc088a5bcf20517cbcd838f8		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3434 bytes
xlm_sheet_01.xml
c70a51acb5791492ef3f1e96d2217abba4360bc0964fdbbf0b281da430450073		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 908 bytes
xlm_sheet_02.xml
84b5606b26315521210c94dce2556ab11c1d4148efb57521cf114d2065ef725b		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 905 bytes

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