Office (OOXML) / .XLSX malware analysis — malicious · a7b947b431b98989

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: c3b98da917bab86ac4bf76209067e249 SHA-1: e3ead4ac71129fdaeb7ce6e40bf5f4ee60e9d155 SHA-256: a7b947b431b98989d962e5256cdcb9c0acad62a4ca2a760b004993d232a57b14

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 executing malicious code. The macro sheet itself is heavily truncated and obfuscated, preventing a detailed analysis of its specific actions or payload delivery. However, the presence of Excel 4.0 macros strongly suggests an intent to run arbitrary code.

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` `aff8c41ba0003ec5a3cf4b2a40268ce9c1290eee361a70a98f0e4882c6861610`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	231804 bytes

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