Office (OOXML) / .XLSX malware analysis — malicious · 6a5cd724baaebc19

MALICIOUS

Office (OOXML) / .XLSX

269.5 KB Created: 2021-10-10 18:55:08 UTC Authoring application: Microsoft Excel 12.0000

MD5: 4e6d8b34d4441d66984a1b4fa51fe561 SHA-1: a991079981a98f9cf3ceba151ce56d39fa522b5d SHA-256: 6a5cd724baaebc19773830980de192cfa10e9d921469153399e656fbdd0ff972

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The critical heuristic firing indicates the presence of Excel 4.0 macros within the XLSX file. These macros are known to be used for executing malicious commands, often to download and execute further stages of malware. No specific IOCs were extracted, and the macro content was truncated, limiting further analysis.

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` `ff870e4227281bc5bd6a548d2e86060af2535d15ada253c052a9851d83ea6ad0`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	635500 bytes

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