Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 85f66f45a2ed43ab…

MALICIOUS

Office (OOXML) / .XLSM

20.9 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-18
MD5: 728e62e7b36a04891138265b2f01ce6c SHA-1: 4ec1af8c5620ecb89577ec5b4628e70a2c03b831 SHA-256: 85f66f45a2ed43abfbc6ee53fb47a910a08c2e5f99ca17c3af7062bf4b03c313
250 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 XLSM file contains Excel 4.0 macros, identified by the 'OOXML_XLM_MACROSHEET' and 'OOXML_XLM_DANGEROUS_FN' heuristics. The macros are designed to download a payload from one of the provided URLs, such as 'http://bctconsulting.se/HelenaWEB/Xf1rQukg8HjfItb9x/', and execute it using 'regsvr32.exe' to drop '\windows\SysWow64\kytk.dll'. 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 http://bctconsulting.se/HelenaWEB/Xf1rQukg8HjfItb9x/
    • http://bnbengineering.com.pk/cgi-bin/6n8q1OFBzyGyPSJ/
    • http://bioscan.ch/backup_nov05/n6S3o4q9dG8050/
    • http://grworld.com.tr/fonts/TPxLPt9Us5ALpvY/
    • https://binaghetta.it/wp-content/gdONbcsI6Q9/
    • http://bytesenbits.nl/cgi-bin/OjOn8icwhyf22SzegYA/
    • http://abildgren.dk/webmail/XY8XstOvGiLx/
    • 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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