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

Static analysis result for SHA-256 e56b41ac62c64272…

MALICIOUS

Office (OOXML) / .XLSX

72.7 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: c03c3032c5d29cc70aeb5b4c5030b0b7 SHA-1: bda8f81cd56196682bc49039229147a7162f57c5 SHA-256: e56b41ac62c64272567f6bdb2f65ec72b88dcbe7472b6079a1b1ec1c5bd75c42
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. The extracted macro content, though partially truncated, reveals a path construction that strongly suggests the execution of a file from 'C:\ProgramData\excel.rtf'. This points to a macro-based execution attack pattern, common for initial payload delivery.

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
e77baab6af3a79e018186af15d8642e23a58baa8f29d74fb10a7ddc252668a91		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 99487 bytes

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