Office (OOXML) / .XLSX malware analysis — malicious · 558aacbcc50755ff

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 27769a494737638fc8b75033bb03252e SHA-1: 4a8bd03a9e3d334cc4674f0f391bfea273343f02 SHA-256: 558aacbcc50755ff47a4339dce681bd7158dc1c5c862fc390ded0e153edb95ae

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros, which are known to be used for malicious purposes. The heuristic firing indicates the presence of these macros. 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` `895168726c300b5a4f8aae651be1b31651ee8a66e9cbd52e253c5aa59506ca8a`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	603315 bytes

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