Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 a4fc34b42844531d…

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: c9f0465f9864d0f4d3dc7beaf1748194 SHA-1: 7b277c3b6ae2d9de9c0376c159d49e965f46537a SHA-256: a4fc34b42844531d99ff3b44709b0c15321b61abb3bf78af0f5b91cf1873685b
250 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1071.001 Web Protocols T1105 Ingress Tool Transfer

The file is an Excel 4.0 macro sheet (XLM) that utilizes dangerous functions like FORMULA to download and execute a payload. The embedded URLs point to potential staging servers for the second-stage malware. The ClamAV detection and the use of XLM macros strongly suggest Emotet, a known downloader family. The script attempts to download a file to \Windows\SysWow64\kytk.dll and execute it via regsvr32.exe.

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://benconry.com/wp-includes/eUXuRrm1G6bRZ/
    • http://atbiotique.com/images/ESistuSH6DbQFkxTz/
    • http://automotorahorizonte.uy/wp-snapshots/r1G/
    • http://speziale.it/cache/vcVndjk/
    • http://actividades.laforetlanguages.com/wp-admin/PXMxDnqZrr/
    • http://www.atelierkikala.com/Facebook/2pfL2EhoN9MusmXv/
    • https://bencevendeghaz.hu/wp-includes/ob9w4byJ85B/
    • 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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