Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 89317a8a0937137f…

MALICIOUS

Office (OOXML) / .XLSM

21.2 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-20
MD5: 6288a521739ff965f9538aed5077af73 SHA-1: c9e7a1d5e2bdfb728e07098b7d105f12d27dfe6a SHA-256: 89317a8a0937137fb224d6406079b0a3a4372ea840344eb52c6466d992cd80c7
250 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file is an Excel 4.0 macro-enabled spreadsheet (XLSM) containing a hidden sheet with a defined Auto_Open name, indicating malicious intent. The macros utilize dangerous XLM formula APIs to download and execute a second-stage payload. The script reconstructs the command 'regsvr32.exe rfs.dll' and uses multiple URLs to fetch the payload, with the primary URL being http://beetle-j.jp/wp-admin/ErM4mW05tdj/. The ClamAV detection name 'Xls.Downloader.Emotet03220-9941789-0' strongly suggests the Emotet family.

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 http://beetle-j.jp/wp-admin/ErM4mW05tdj/
    • http://e3technology.in/2checkout_integration_php/rDcr1Wl90WWA9M/
    • http://bjornbol.dk/wp-includes/ve4cnkjsUMWXC5Cb2bJ/
    • http://bebesel.com.tr/cgi-bin/1wy3oHO/
    • https://brutobrasil.com.br/pdf/toO18cIP3/
    • http://biesenbeek.nl/familie/b6KKlrfH75GD3dHojB/
    • http://bcelectronics.co.za/wp-content/grKnz1V/
    • 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
f9ef0dd03a642623a126a648a3e3b498d8403d13558799b8b55ca81a239f78e5		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3968 bytes

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