Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 03907b816aea98d1…

MALICIOUS

Office (OOXML) / .XLSM

38.8 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-18
MD5: 386a34ab71e927c7506f1551b61494fb SHA-1: 1f05d7fb284fd023f9236f2460a0d6812693e909 SHA-256: 03907b816aea98d137570400cbde7ebfd34180abce60618204ec9ff380ea9448
250 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file contains Excel 4.0 macros, indicated by critical heuristic firings for XLM macrosheets and dangerous API calls. The macros are designed to download and execute a second-stage payload using `regsvr32.exe` from a list of embedded URLs. The ClamAV detection as 'Xls.Downloader.Emotet03221-9941790-0' strongly suggests the Emotet family.

Heuristics 6

  • Excel 4.0 macro sheet (2 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.Emotet03221-9941790-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03221-9941790-0
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 5 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
    • 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
a0c0f3e40bb0bcb71f69feab4a546d6971a6ad22d842de019237e043f0081a43		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1772 bytes
xlm_sheet_01.xml
2f8447d752b9aa82298eff83e8f17bd62a63f1ba62e6405681193f1dc7729f67		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 4474 bytes

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