Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 b10ed69f8e9b0da7…

MALICIOUS

Office (OOXML) / .XLSX

50.9 KB Created: 2022-03-30 21:24:25 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-31
MD5: 045cc1be5d94f6f085c65d5037c331aa SHA-1: bec953f4c735c740e524f7a9a2d38ea99679461c SHA-256: b10ed69f8e9b0da709cfaae8849ada80e45de31d91fbc07e9bf9a838aa73b1f9
298 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 Excel 4.0 macro-enabled spreadsheet. Critical heuristics indicate the use of dangerous XLM formula APIs, specifically FORMULA, which is used to download and execute payloads. The DOC BODY and script content reveal that the macro attempts to download a DLL from one of the provided URLs and execute it using regsvr32.exe. The ClamAV detection as 'Xls.Downloader.Emotet' strongly suggests the Emotet family.

Heuristics 8

  • 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.Emotet04220-9942583-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet04220-9942583-0
  • 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.
  • External hyperlinks (3) low OOXML_EXTERNAL_HYPERLINKS
    Document contains 3 external hyperlinks — clickable URLs are stored as external relationships. First target: https://rumkeke.com/wp-admin/A8/","
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 7 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://harleyqueretaro.com/renew2019/Back2016-12-22/cv/data/RjuiFMp4Fsp/
    • http://hoatuoiso1.com/replace/fVea/
    • http://www.grandfurniture.com/thegrandbrands/eGd55tEm9qkPNOhViP/
    • https://rumkeke.com/wp-admin/A8/
    • https://www.restaurantgaig.com/wp-includes/HLDoANj/
    • http://www.hiway91.com/wp-content/Y/
    • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
2ef95bf166dbf14d5280e19f3c7c81a3e8bfde62220401b1871bb39e3fb952d3		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3358 bytes

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