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

Static analysis result for SHA-256 e593b43c468f1c38…

MALICIOUS

Office (OOXML) / .XLSX

66.6 KB Created: 2021-03-15 18:26:22 UTC Authoring application: Microsoft Excel 16.0300
MD5: 16ccf07b3e1df46cbdbb04b4102dca2c SHA-1: e3b05d3d554c0a21630769d8ba0ade598836c019 SHA-256: e593b43c468f1c38b1ff688ab87b9c0265692531d981f12a67362ae62f134a51
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. While the macro content is heavily truncated and obfuscated, the presence of such macros strongly suggests a malicious intent, likely to download and execute a secondary payload. The file type and the nature of the heuristic point towards a macro-based attack vector.

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
4e3c8883b95c67e9968a1613e737b4582eb0131060db15f7211c005707dbf2c2		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 93382 bytes

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