Office (OOXML) / .XLSX malware analysis — malicious · e063241257a08404

MALICIOUS

Office (OOXML) / .XLSX

64.0 KB Created: 2021-03-14 21:05:29 UTC Authoring application: Microsoft Excel 16.0300

MD5: 731e260800e3ef3a8c2e6f91642c65cb SHA-1: d3de428f3eecb22e6bf3d39738abbe3407c81b2f SHA-256: e063241257a084043b2718acdf6655ad492202b7f190150733bbbba9a00db987

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications

The critical heuristic firing indicates the presence of an Excel 4.0 macro sheet, which is a known method for executing malicious code within Office documents. While the macro content is heavily obfuscated and truncated, the structure suggests it is designed to download and execute a secondary payload. The lack of clear indicators for a specific family or further IOCs limits the confidence in a more precise attribution.

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.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `866d455a20ae6a6df9f777f044296b3949bbad13c5246aa06e2dbf189fee0060`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	88880 bytes

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