Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 8ab676c1579f29fa…

MALICIOUS

Office (OOXML) / .XLSM

40.0 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-04
MD5: 7267d0f212b2f8237c4d3b1f8ac53a3d SHA-1: 1762ea9ecb7a41be457637337566399963ab8232 SHA-256: 8ab676c1579f29fa68385da91722f463592791c3206c9f29c2e821eaf9df2741
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, which is a known delivery mechanism for Emotet. The macros utilize dangerous XLM functions like FORMULA to construct and execute commands. Specifically, it uses regsvr32.exe to download and execute a payload from a list of embedded URLs, such as http://foroviviendaparaguay.com/wp-admin/hx8U6XMffnkv8HI2Oig/. The presence of Auto_Open defined names and the use of regsvr32.exe strongly indicate a downloader functionality.

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.Emotet03220-9940731-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03220-9940731-0
  • 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://foroviviendaparaguay.com/wp-admin/hx8U6XMffnkv8HI2Oig/
    • http://ghsjalkherabsr.com/oz03n/6XeYLjFXcFE/
    • http://www.aacitygroup.com/wp-content/EkY9/
    • http://en.pachammer.com/wp-content/vIG/
    • http://ghsmadonabsr.com/wp-includes/Of4kQNCp2WLy0F4B/
    • https://theoutsourcedaccountant.com/images/nFikTQmP/
    • http://foroviviend
    • 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
94965f752a1e7be43d1bf315273deead3f139a3387887345fe87c8486a290891		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3704 bytes
xlm_sheet_01.xml
351feaae7418c65a74e6a0ba66009b604df9b81504ed5e5dbe43c90a37e65a77		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1278 bytes
xlm_sheet_02.xml
e7d03b45d335889b8dde35df06f3ab1a1e873e88cc653bc40b000e1458d4c807		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1152 bytes

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