Emotet — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 a6ba8a487c1028f3…

MALICIOUS

Office (OOXML) / .XLSX

262.2 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-01
MD5: 736b3818dc50e4dc23da9e52bd97e1dc SHA-1: e501c5cab5dc6b426041880a935960aacb64f395 SHA-256: a6ba8a487c1028f36f9bf7f4f85eb72041bfbac31eb6be2a35e58d588736020a
180 Risk Score

Malware Insights

Emotet · confidence 95%

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

The file is identified as malicious by ClamAV with the signature Xls.Downloader.Emotet-OOXML_XL-af43432fbcb8603c-9980048-0, indicating it belongs to the Emotet family. The presence of multiple Excel 4.0 macro sheets within the XLSX file strongly suggests the use of macros for malicious purposes. These macros are likely responsible for downloading and executing a secondary payload, a common tactic for Emotet.

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
cfdec4781d38aa85d46e4a7bdaa3a4d72c8a73677a644a74bd54ff01f9c4fbcc		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin 2376 bytes
xlm_sheet_01.bin
f1d88aff69022ae0d15400e52c498eb1e01f1d88da44af58d08b588cf81edeba		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 428 bytes
xlm_sheet_02.bin
8d092ab692439a37110203e92834516fd002e1321c2b7624010918f36f321373		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet2.bin 428 bytes

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