Office (OOXML) / .XLSX malware analysis — malicious · bd657afb43737f1d

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 8f3851e0e2950ab509c1d422d7c51488 SHA-1: 08fba263ba90c47b595c13240e7215fc1e8137a1 SHA-256: bd657afb43737f1da0cceccdd7b702a71070d188ab59b03d79544ddf95f7bafd

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 such macros is a strong indicator of malicious intent, often used to download and execute further stages or exploit vulnerabilities. The file's metadata shows it was created with Microsoft Excel 12.0000.

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` `32180e6b915546b5603b3016812e8b21aa6689592cb3cf5db0b6b3cca59c267a`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	151687 bytes

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