Office (OOXML) / .XLSX malware analysis — malicious · ac499be152fd3bf1

MALICIOUS

Office (OOXML) / .XLSX

98.0 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 16.0300

MD5: f53fdbf650f8079b40e9ddb2c7fe41c9 SHA-1: 062b26e37cd5eb8cd70b11bd89f1908268880d99 SHA-256: ac499be152fd3bf1a958d67233e5bf1484360892d8c6040e0941748735939f2a

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macro sheets within the OOXML file. While the macro content is heavily obfuscated and truncated, the presence of these macro sheets strongly suggests an attempt to execute arbitrary commands upon opening the document. This is a common technique for initial payload delivery.

Heuristics 1

Excel 4.0 macro sheet (3 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 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`emf_00.emf` `ab58818ae1864807b22f8a58a75f7fa8703ecb19a2352bdb47469f366b868e59`	ooxml-emf	OOXML EMF part: xl/media/image2.emf	1108 bytes
`xlm_sheet_00.bin` `7ba8c7dae215c3d653270796d8570b3810c64068590cf64325562d684e829370`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	1340 bytes
`xlm_sheet_01.bin` `cb1f1a0b36df7c5b1ecd6c45b74a2d4711b2827f0ee30f82c9df4f6bc63e617f`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet2.bin	1509 bytes
`xlm_sheet_02.bin` `ab6060707b634032a9e28cdf4014bbeee5441e8ba06b1724bdb26e4c68089d59`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet3.bin	1296 bytes

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