Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 185e56485c357842…

MALICIOUS

Office (OOXML) / .XLSX

1.01 MB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-04-13
MD5: acaaff95a54fc331c23e0c008367a7e3 SHA-1: 69d023475ca9649c129664e7516ae670a307f825 SHA-256: 185e56485c357842fc53c59fc918a3c6c4fd0a3c399b61b31c82b259c749ff4a
140 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file is identified as malicious by ClamAV with the signature 'Xls.Downloader.Emotet-OOXML_XL-af43432fbcb8603c-9980048-0', indicating it is likely an Emotet downloader. Critical heuristics confirm the presence of Excel 4.0 macro sheets, which are commonly used to execute malicious code. These macros likely download and execute a second-stage payload, consistent with Emotet's behavior.

Heuristics 3

  • Excel 4.0 macro sheet (4 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. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.
  • ClamAV: Xls.Downloader.Emotet-OOXML_XL-af43432fbcb8603c-9980048-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Emotet-OOXML_XL-af43432fbcb8603c-9980048-0
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object

Extracted artifacts 7

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
93b1cea548cf9d5f4ac6f64afb7be18c1737b3dbdea4bd0aadb26bf7b8d79518		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 3099136 bytes
ooxml_oleobject_00_ole10native_00.bin
a6724425b761391a2288cdb0e402bdc8cf2de9a4e93260c95af92b78344a367e		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: Ole10Native 3072068 bytes
emf_00.emf
3f0f6bb70f3d65dcc8d248d78ac320bcc22b1148ea5fdd2c1043065d03460133		 ooxml-emf OOXML EMF part: xl/media/image1.emf 6144552 bytes
xlm_sheet_00.bin
c2021f3cd7a15d00132d83f817974fbaa3dcba6ac2832cfc59e171f9725dd194		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin 1816 bytes
xlm_sheet_01.bin
2e5c804d6e95dfaf0aedb09d41e9590a894531b97c42c90478ac456e59a2157a		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.bin 832 bytes
xlm_sheet_02.bin
f0a9425b8507f47d4bffbfc9986e6f77a1eec5a7b094745fec3307154c314949		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 402 bytes
xlm_sheet_03.bin
7b780847888f3179b9a2306b1d9dd4b22d991fb4b1641b18d3184a5b6ac9038f		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.bin 322 bytes

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