Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 f941bdf4fdb5690d…

MALICIOUS

Office (OOXML) / .XLSM

90.2 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-02-23
MD5: 689f0b4887f9be51e0e8ff0852ca7d6d SHA-1: ecb75fa68a6b1aa49de5a038674ddd20bf1ac46f SHA-256: f941bdf4fdb5690d8ffec50d9f867bcf6c548c1c74fe9087f44a3b23012bee23
290 Risk Score

Malware Insights

Emotet · confidence 95%

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

This XLSM file contains Excel 4.0 macros, identified by critical heuristic firings. The macros utilize dangerous functions like FORMULA to download payloads from multiple URLs, including 'http://www.ajaxmatters.com/c7g8t/zbBYgukXYxzAF2hZc/'. The document body explicitly shows the use of 'regsvr32.exe' to execute these downloaded payloads, indicating a downloader pattern. The ClamAV detection name 'Xls.Downloader.EmotetExcel02220-9940032-0' strongly suggests the Emotet family.

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.EmotetExcel02220-9940032-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.EmotetExcel02220-9940032-0
  • 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://www.ajaxmatters.com/c7g8t/zbBYgukXYxzAF2hZc/
    • http://www.beholdpublications.com/home/BABxyyWZx8Vu/
    • http://explorationit.com/screwing/AxLm/
    • http://donboscoschoolputhuppally.org/wp-content/UuQ7LBsPoGu9Q/
    • http://myclassroomtime.com/mongery/ZlPsROtQiXIujmJmAA/
    • http://www.ajaxmatters.com/c7g8t/zbBYgukXYxzAF
    • 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
fc9253ffcb683b17b2963a329e0d1078315a68ecc8af492238ff27be69741b1f		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3613 bytes
xlm_sheet_01.xml
6922c877af9b5ffe857609a5d410eac153e8905bd35dfd19cf6ef8e3fb0636e6		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1204 bytes
xlm_sheet_02.xml
60579741b1b65a4181fd818a651bece32da461189f50a30098e233a7c5fed525		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1227 bytes

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