Office (OOXML) / .XLSX malware analysis — malicious · ecb0e8c5f0f2fa78

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 55e5f248080468f6355ef7cfdad1b0cd SHA-1: 14ef9001e6e8df069cc054edc7d065339a17e84f SHA-256: ecb0e8c5f0f2fa786393a86c9b55ba5575d182d078929da1e5eb4a120866a533

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample was identified as an Excel 4.0 macro sheet, which is a known method for delivering malware. The macro sheet itself is heavily truncated and obfuscated, preventing a detailed analysis of its specific actions or payload. Therefore, the exact attack pattern and IOCs cannot be determined with high confidence.

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` `3c97e97306165d4cc1dfdc71a8295f1c21e1b0f58d7bbc8f1b55a8e74b4210fd`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	243761 bytes

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