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

Static analysis result for SHA-256 4e45073544dfd8b3…

MALICIOUS

Office (OOXML) / .XLSX

107.8 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: d0b8ebf0f56c6a63df32db4de4408ed7 SHA-1: 12dda98fa3c11213df66bf03148637e5138462a7 SHA-256: 4e45073544dfd8b34da81eb95355d9c0e1b0948b0e3337a863d5331678109f65
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 an XLSX file. The extracted script content, though partially obfuscated, suggests an attempt to execute a file located at 'C:\ProgramData\excel.rtf', likely a second-stage payload. This points to a macro-based execution attack pattern.

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
cf132f60cb23f2620fc37f3527ccb67eba7bd4ba638838aa5373a63c51ad9a6a		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 286549 bytes

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