Office (OOXML) / .XLSX malware analysis — malicious · b214193acfdcd494

MALICIOUS

Office (OOXML) / .XLSX

110.7 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: f820bc2bb27f36796ee0379061632511 SHA-1: 8559b5899ba0e7bdc4fe0877b39faa9e3a7d5760 SHA-256: b214193acfdcd49438a1c40ab18ff00e8c6774295e920c6e51ae662946fd4deb

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. Excel 4.0 macros are a legacy feature often abused for malicious purposes, typically 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` `b720d3586ec022c53a7f8adb05f48751b457b2968b16e4a23f99731186a1f7fa`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	256127 bytes

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