Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 3857484ca3a3e0fb…

MALICIOUS

Office (OOXML) / .XLSX

240.1 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-05-06
MD5: 8519abcae371d7e2c92acb82955bd927 SHA-1: 1eef01ef35fc6cc8f22348a457a8520e1daaf817 SHA-256: 3857484ca3a3e0fbafebcdffff8076266482a4fc86bdc9d1fcf0a6c4c8d6d5aa
120 Risk Score

Malware Insights

Emotet · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

The sample contains Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. The ClamAV detection explicitly names this as 'Xls.Downloader.Emotet-OOXML_XL'. The macros appear to construct URLs such as 'ordisOS.com/9bVAa06WXzsj/Knhfn.png' and 'ncelltech.com/qVFmE4M5BR/Knhfn.png', likely for downloading a second-stage payload. This aligns with Emotet's typical delivery mechanism.

Heuristics 2

  • 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.
  • 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
56ddade77d7e32930aed597b7717dc3eff76587b10e692229752e1522d34b56e		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 998 bytes
xlm_sheet_01.bin
6596a1a91ff1e8511c9bacd26b0ed25c9acae41209ca6bf1af5b0af2340b0150		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.bin 2652 bytes
xlm_sheet_02.bin
4aa675529670262d62d2072b2082c4d2e236f5f4a3a27db04178011a4f7c7c65		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet3.bin 1336 bytes

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