Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 4098eed9c3a2b676…

MALICIOUS

Office (OOXML) / .XLSX

83.3 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: 157aa940027df34e6dc58c2d036e98fe SHA-1: e723626131c02cd14ab0108e6740aeae51ff1978 SHA-256: 4098eed9c3a2b676312fcf3dcdbcf4f18affb50ab9b31d02868aeee1b6e7d932
290 Risk Score

Malware Insights

Emotet · confidence 95%

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

This XLSX file contains Excel 4.0 macros, identified by the OOXML_XLM_MACROSHEET heuristic. The macros utilize dangerous XLM functions like FORMULA to download and execute payloads. Specifically, the macros construct and execute a command using rundll32.exe to download content from multiple URLs, including http://2.arthaloca.com/styles/dS5RNprosfCabLtYEwO/, http://robotically.xyz/wp-content/XtKkx/, and https://notesculture.com/wp-includes/LuQtO3MiyJFFcF/, and save it as ..\wxeu.ocx. This behavior is consistent with Emotet's typical delivery mechanism.

Heuristics 7

  • 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.EmotetExcel01223-9936530-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.EmotetExcel01223-9936530-0
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 3 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://2.arthaloca.com/styles/dS5RNprosfCabLtYEwO/
    • http://robotically.xyz/wp-content/XtKkx/
    • https://notesculture.com/wp-includes/LuQtO3MiyJFFcF/
    • http://2.arthaloca.com/st
    • 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
bc434a02f8174c59a684fc724af55a55ed12e02f1e0886ee1818bcfaa8302510		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 2827 bytes

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