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

Static analysis result for SHA-256 82de959ab31e38d1…

MALICIOUS

Office (OOXML) / .XLSX

71.4 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: 600fafbbf77b438cb016d8c2b86e05d2 SHA-1: 1357433144031892b904c6b9e034625092c3582d SHA-256: 82de959ab31e38d1deefb3c20dca843bf2b092b5b78c887e60022d5035223974
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. Analysis of the macro content reveals it attempts to write a file to 'C:\ProgramData\excel.rtf', likely as a staging area for a second-stage payload. The obfuscated nature of the macro content prevents a more detailed analysis of its execution flow or specific download URLs.

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
5e994c7e1c8dd2a4064390f0f3d5848efb002cf05f6077dcb052ca7cc431e631		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 104878 bytes

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