Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 edc9117aabb326b9…

MALICIOUS

Office (OOXML) / .XLSM

20.9 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-17
MD5: e20c93ab0804b6c7b6e0ad9c6d1e770c SHA-1: 9b900586d9f93ac31217ed7850dd07d5dad5dfbe SHA-256: edc9117aabb326b99df858a1e8a003ea83b4d4504b8816b21c4f51d46f67a286
250 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File Execution: User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1105 Ingress Tool Transfer

This Excel 4.0 macro sheet utilizes dangerous functions like FORMULA to construct and execute commands. The script concatenates strings to form URLs and file paths, ultimately downloading and executing a payload. Specifically, it reconstructs the URL 'http://osmani.atwebpages.com/wp-content/Ynwrr/' and attempts to save and execute a file named 'kytk.dll' using 'regsvr32.exe'. The ClamAV detection as 'Xls.Downloader.Emotet03220-9941789-0' 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.Emotet03220-9941789-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03220-9941789-0
  • 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
  • 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://amplamaisbeneficios.com.br/contratos/MWnnZG/
    • http://bredabeeld.nl/OLD/eavGp2KOdwXT/
    • http://kogelvanger.nl/picture_library/1MNqKan2FhWtQg5Uacu/
    • https://50-50aravidis.gr/thesi/wmL/
    • http://bcingenieria.es/phpmailer/Z7fmcI7Va/
    • http://www.cagataygunes.com.tr/stylesheets/uqK4kfhG4RAuRIA2/
    • http://osmani.atwebpages.com/wp-content/Ynwrr/
    • 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
bd1141b96e73c592d43d300feb4a2bed92034dffba7d5e49bf95a81f1348fbbc		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 4144 bytes

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