Office (OOXML) / .XLSX malware analysis — malicious · bddac5e8756f90db

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 74c22c82087697ee4344539d2b4f2867 SHA-1: 277cda33834cf0d225b70365f679e5221df11bd3 SHA-256: bddac5e8756f90dbac0b74735f14f2ad797760c23cee26c10e8dedb7a6f95f61

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 heavily truncated and obfuscated, the presence of this macro sheet strongly suggests an intent to execute arbitrary commands. The specific commands or payloads are not discernible from the provided excerpt.

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` `350303143b68477470e1834601b3bfe502e8062568e44b4fea9b157817b7655c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	586981 bytes

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