Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 3b42c27be13b8ac6…

MALICIOUS

Office (OOXML) / .XLSX

55.3 KB Created: 2021-03-14 21:03:54 UTC Authoring application: Microsoft Excel 16.0300
MD5: 336849f055255ad626982c22a3341e81 SHA-1: 620e24f20df2e9465d090ae18b566568e390fdd2 SHA-256: 3b42c27be13b8ac6bc5533315c7f2fdcdab0e6a95d4693fa3fe6ba64286ed162
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. These macros are known to be used for executing arbitrary commands, which is a common technique for initial access or payload delivery. The script content is heavily obfuscated and truncated, preventing a more detailed analysis of its specific actions or the reconstruction of any URLs or commands.

Heuristics 1

  • Excel 4.0 macro sheet (1 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.bin
a0d2d8f3fdcc993d9e3e5ae16f3d3bb15f4346ad58894e84fb8edfd7b3acab1a		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 92099 bytes

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