Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 d625d6bb8fa75611…

MALICIOUS

Office (OOXML) / .XLSX

233.8 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-09
MD5: f46e201bb0916fccc71f51a258700664 SHA-1: 58611fffdc2272ccc50ff2dac3979f1954974331 SHA-256: d625d6bb8fa75611966eb29ec7386c58dd25c73dc1bffbb993d38443a198b7ed
180 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample is an Excel file containing Excel 4.0 macro sheets, a known delivery mechanism for Emotet. The ClamAV detection explicitly names Emotet. The macros are heavily obfuscated, but the presence of XLM macros and the ClamAV signature strongly indicate a downloader functionality, likely to fetch and execute a second-stage payload.

Heuristics 3

  • Excel 4.0 macro sheet (3 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.
  • XLSB international XLM macro sheet hidden in .xlsx critical OOXML_XLSB_INTL_MACROSHEET_IN_XLSX
    OOXML package is named .xlsx but contains XLSB workbook parts and an international Excel 4.0 macro sheet. This hides XLM macro execution from scanners that trust the extension or only inspect XML worksheet parts. The technique is macro execution, not a document-parser CVE.
  • 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

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
ba41a11b1be4eaa156bff86597ea809a971edc4d801f70a4529d6d84b93c19c0		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin 2469 bytes
xlm_sheet_01.bin
294fba96533e16b8e32fcc670b890c44fe9dfc759e5d84743c74026ba7bd4a20		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 428 bytes
xlm_sheet_02.bin
f0daf3cbff097906d4170f35f5f5c2394e9b70d2a487782035c708617ae7b9ec		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.bin 428 bytes

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