Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 b60cda227861fe72…

MALICIOUS

Office (OOXML) / .XLSM

46.6 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-01
MD5: e9f5fd2e9ab44bde618a8bb3891857b7 SHA-1: 5e071b7caf6c87dc40f2188cedced1beaf4e6e58 SHA-256: b60cda227861fe724f9e0a504ced4e726f5b7c7e5a7933c12e6d8e306dbc0aff
290 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1218.010 System Binary Proxy Execution: Regsvr32 T1059.005 Command and Scripting Interpreter: Visual Basic T1105 Ingress Tool Transfer

The file is an XLSM document containing Excel 4.0 macros, identified by the 'OOXML_XLM_MACROSHEET' and 'OOXML_XLM_DANGEROUS_FN' heuristics. The macros are designed to download and execute a payload using 'regsvr32.exe' with URLs pointing to potentially malicious content. The ClamAV detection as 'Xls.Downloader.Emotet03220-9940726-0' strongly suggests the Emotet family. The script's intent is to download and execute a second-stage payload from the embedded URLs.

Heuristics 7

  • 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.Emotet03220-9940726-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03220-9940726-0
  • 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 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://dan-bau.com/wp-includes/css/dist/h2plh7xZso/
    • http://prevozkop.rs/qnov/n017r0EEa/
    • https://advisereviews.com/wp-content/2NyZZiJ6KEzPPrbx/
    • https://businessandhr.com/w/xrB/
    • https://aplicativos.xyz/apk/49Wq5MN/
    • http://www.equus.com/2i8yt/0kWhkppl8oTFCeYu9gS/
    • http://dan-bau.com/wp-includes/c
    • 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
c2beed76b90707ab99d3556b095847fbe67565665bab2978d4d40d1b769c68e7		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 4017 bytes
xlm_sheet_01.xml
3f1e04bcb932a0d7a0ca09ad6e05d398d7a144c4cda86314010c0ec3e9f94573		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1278 bytes
xlm_sheet_02.xml
3877aa64e871d2d6fcc766f5b3af64ba0d301f656023d2e6e43652b8210d827c		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1152 bytes

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