Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 8ab926bcb1486ffe…

MALICIOUS

Office (OOXML) / .XLSM

31.6 KB Authoring application: Microsoft Excel 16.0300 First seen: 2022-04-01
MD5: f6f7b350790b6502a62899f677f9063a SHA-1: 7ac12d3baee383e240cb9c3166b19c8498261834 SHA-256: 8ab926bcb1486ffe74ead60a42d176816f06d103576662bec0876b3dea641016
250 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File T1071.001 Web Protocols

The sample is an XLSM file containing Excel 4.0 macros, which are known to be used for malicious purposes. The macros utilize dangerous functions like FORMULA to construct and execute commands. The reconstructed command string indicates the intent to download a file named '..\xewn.dll' and execute 'r"egsvr"r"32.exe', likely to download and run a second-stage payload. The ClamAV detection as 'Xls.Downloader.Emotet04220-9942581-0' strongly suggests the Emotet family.

Heuristics 6

  • Excel 4.0 macro sheet (1 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.Emotet04220-9942581-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet04220-9942581-0
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 7 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 https://jetanahtarcilingir.net/wp-admin/dNZqOigWx5XCnSlZ/
    • http://formulationdrugstore.com/wp-includes/UTDuP5ti/
    • http://flexaviationcenter.com/bin/mvd4h6/
    • https://brutobrasil.com.br/pdf/LubLsUkjN/
    • http://flumedya.com/assets/zahEwukU/
    • 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
4153191ccbeaead436d640cd9bad7b4c39fa54474c8ec9a17be8e3e4600146ed		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 3602 bytes

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