Emotet — Office (OOXML) / .XLSM malware analysis

Static analysis result for SHA-256 d37371c5a3ff4b7f…

MALICIOUS

Office (OOXML) / .XLSM

33.0 KB Created: 2015-06-05 18:17:20 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-16
MD5: 9697646512b064a63a13eb7f70422ce7 SHA-1: ade71955f5d17bf3f155a89b2698a6d75e6ab342 SHA-256: d37371c5a3ff4b7f1d85e327b299f5bf4ebc15df28227a96d5368ee5165884ad
290 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1218.010 System Binary Proxy Execution: Regsvr32 T1105 Ingress Tool Transfer

The file is an Excel 4.0 macro-enabled spreadsheet (XLSM) containing an Auto_Open macro. The macro uses dangerous XLM formula APIs to download a payload from multiple URLs, including "https://casache.com/web/n3jxwXXwa/". It then uses regsvr32.exe to execute the downloaded payload. The ClamAV detection explicitly names this as an Emotet downloader.

Heuristics 7

  • 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.Emotet03222-9941788-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet03222-9941788-0
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 5 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://casache.com/web/n3jxwXXwa/
    • http://ccalaire.com/wp-admin/d1pGRa0X/
    • http://careerplan.host20.uk/images/Ls/
    • https://azsiacenter.com/js/sOhmiosLJOgwaP6i5nln/
    • https://www.blessingsource.com/blessingsource.com/rFQ0Ip6lQXXK/
    • http://cdimprintpr.com/brochure2/A9NmYDndZ/
    • http://ausnz.net/2010wc/odSi5tQKkCIXEWl9/
    • 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
db0a59e4a9d5995912532cf04297a579397bf9cc37c53dfcf4ddd0de285133c8		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml 4122 bytes

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