Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 3e82864afe94d3c0…

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: 79900d00b8170096f35e4ce1b8666b1b SHA-1: ba492262d99bc07afb306601e44bde02caf45b79 SHA-256: 3e82864afe94d3c0229eb980a61b942c2a15f00231ade2c1361acadae83c56ed
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_AUTOOPEN_DEFINEDNAME' heuristics. These macros utilize dangerous functions like FORMULA to download and execute payloads. Specifically, the document body and heuristics indicate the use of 'regsvr32.exe' with a downloaded OCX file from various URLs, consistent with Emotet's typical delivery mechanism. The script's intent is to download and execute a second-stage payload using regsvr32.exe.

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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