Office (OOXML) / .XLSX malware analysis — malicious · 2a06a99cdf221980

MALICIOUS

Office (OOXML) / .XLSX

80.0 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: 8b1bbb00c988c26066138117caec5586 SHA-1: a72c02ec4a281054005583da2d2596cb9be6d188 SHA-256: 2a06a99cdf221980cedbfd9910ad8a26ab797f3a6aa597816dbc5341b658efb6

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 the XLSX file. While the macro content is truncated, the presence of such macros 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 (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` `b19e554ec5f5fe62ae1389cf9550bac94e83627130a82c723af712156a1fb4f7`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7879 bytes

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