Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 f04a0cea24ec441c…

MALICIOUS

Office (OOXML) / .XLSM

95.3 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-02-25
MD5: ace991f255bdbe243d88ad3c43add45e SHA-1: 02cc019afee08aa131d4f87de4f3bb571c460061 SHA-256: f04a0cea24ec441c2710849fb6abb9ace2780f0bef9ea92d34f9157f6114bb7a
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, as indicated by multiple critical heuristic firings. The macros utilize dangerous functions like FORMULA to construct and execute commands. Specifically, the macros appear to be assembling URLs and passing them to regsvr32.exe for payload download and execution, a common technique for Emotet. The ClamAV detection also explicitly names this file as an Emotet downloader.

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.Emotet02220-9940466-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet02220-9940466-0
  • 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://gavalisangh.astravit.com/umar-rack/fyMw4DZw1JAB/
    • http://spanish.swslawfirm.com/wp-admin/llSlMYOLL/
    • https://wowssipworld.com/wp-snapshots/7EzFXGUC3p0ffli/
    • https://lucacerullo.com/wp-admin/sZ7Sw/
    • http://198.50.143.158/cgi-bin/PsABe8gznY/
    • http://gavalisangh.astravit.com/umar-rack/fyMw
    • 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
90e37e1ee0ab1fa1161bc9308b04f0f335c97d1feb756097ceb983695c1599e5		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3554 bytes
xlm_sheet_01.xml
966e861f35410708893ffb1f97241504111fc93333012aa9c7613d379c3c60bb		 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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