Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 a0ee3451097f7cc4…

MALICIOUS

Office (OOXML) / .XLSM

51.5 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-10
MD5: 6a3a9c0ba28b770bce200d8e9a3a40a9 SHA-1: c1b0bfa16d6e7d4299bc03cacdd6544471c28468 SHA-256: a0ee3451097f7cc42e6b7e8a5f778ce6ff0d95dee552a9e2a134a21248220ef4
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

This XLSM file contains Excel 4.0 macros, which are known to be used for malicious purposes. The macros leverage dangerous API calls like FORMULA to construct and execute commands. Specifically, it appears to be constructing a command to download a payload using regsvr32.exe and a DLL named 'wn.ocx' from several suspicious URLs. The ClamAV detection as 'Xls.Downloader.Emotet03220-9941298-0' strongly suggests an Emotet family infection, which commonly uses this download and execution technique.

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.Emotet03220-9941298-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03220-9941298-0
  • 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 6 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://www.ajaxmatters.com/c7g8t/kYHGlphIEPNOImddm1/
    • http://185.210.144.149/app/1BKfC3id6jsiH0MC/
    • http://45.76.178.115/sample_sticker/tihOPhaF1l0V/
    • http://academicinst.com/wp-includes/44ZVeVQBkeOG/
    • http://henrysfreshroast.com/0Rq5zobAZB/
    • http://13cuero.com/wp-admin/ff5srrfTNsCju6sD3/
    • http://abinsk.com/cgi-bin/fm63rXkG5Y/
    • 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
aa639861ddc5b5835fc6dc55f810a8cdd345d5a0f25a9228a1e87fb64257685f		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 4348 bytes
xlm_sheet_01.xml
ff04c6af5f59c8590aa4a7b71a1b2742e5c5b487ad6a63ca1d90a970ae623c5f		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1277 bytes
xlm_sheet_02.xml
33ff727dfe6d455b4500b1331dbc121c2312bb4ec71c24948d23118c341dc852		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1213 bytes

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