Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 70853bbc9fa08169…

MALICIOUS

Office (OOXML) / .XLSX

1.19 MB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-05-05
MD5: 7f1e12ad2f10484ebf04d11278dbe50f SHA-1: 3ca5f5e55618914a8910d4fb0c9e2378b1076842 SHA-256: 70853bbc9fa08169e96c929332ef983877bdc0967efa855176904e03ee9f5921
180 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample contains critical heuristic firings indicating Excel 4.0 macros and a reassembled payload. The macros construct commands to execute regsvr32 with specific paths and filenames, suggesting a downloader attempting to launch multiple payloads. The ClamAV detection explicitly names Emotet, a known downloader family.

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.
  • XLM payload reassembled from CHAR()/split formulas critical OOXML_XLM_REASSEMBLED_PAYLOAD
    An Excel 4.0 macro sheet builds its payload inside the formula token stream by concatenating per-character CHAR() calls and string fragments, so no WinAPI name, shell command, or URL is ever contiguous in the .bin for a literal-bytes scan to find. Reassembling the formulas recovered download/execute API names, LOLBin commands (regsvr32/rundll32/mshta/wmic/powershell), or a payload URL — the de-obfuscated download-and-run kill chain.
  • 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 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
emf_00.emf
d6bda36da9e27ea2f8c0420fe1f2b87d573e1c9c5708ebdb49479f5292db2dee		 ooxml-emf OOXML EMF part: xl/media/image2.emf 6145428 bytes
xlm_sheet_00.bin
ecf03862c923fefcab2f06822683ed3235adbb58466fc3c02733de48a348c562		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 1074 bytes
xlm_sheet_01.bin
5a16025ed94a3e1a4ed9f440f85989f9326278b8a9028170d1da2bb8493c3c56		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.bin 2703 bytes
xlm_sheet_02.bin
ebe8249fb8fbfb9b3fd1240f9e8c37aaaebc007f935e60083156978492cc33f0		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet3.bin 1122 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.