Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 8f1c5f756658a90d…

MALICIOUS

Office (OOXML) / .XLSM

115.8 KB Created: 2022-01-19 18:30:24 UTC Authoring application: Microsoft Excel 16.0300
MD5: d0dfa995eb72c89052f341457554b904 SHA-1: 02bb89c9e8c012c33ff10213e785dfc74bd048f2 SHA-256: 8f1c5f756658a90d9007b111594547d054cfdb487aefa255156d07fddd7ee016
258 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious Link: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell

The file is an XLSM document containing Excel 4.0 macros. The macros utilize dangerous functions like EXEC and HALT to download and execute a payload from the reconstructed URL "http://0x5cff39c3/sec/se1.html". The ClamAV detection name 'Xls.Downloader.EmotetExcel01220-9936739-0' strongly suggests the Emotet family. The document body contains invoice-like text, a common lure for financial-themed phishing.

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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