Office (OOXML) / .XLSX malware analysis — malicious · e63ec3f8bf393da2

MALICIOUS

Office (OOXML) / .XLSX

85.9 KB Created: 2021-03-14 21:05:29 UTC Authoring application: Microsoft Excel 16.0300

MD5: d2214a27395a09dd9e994c5dd70b3dfa SHA-1: 91619e0072244de266e3b827f8a097d869e1e3db SHA-256: e63ec3f8bf393da29d5225bb6f1f47b7786839784fa2ee5f867f64f8af8462e3

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Office Open XML (OOXML) XLSX file identified as containing Excel 4.0 macros. The extracted macro sheet content, though truncated and partially unreadable, strongly suggests a downloader or initial execution stage. The presence of Excel 4.0 macros (T1059.005) is a common technique for initial payload delivery. Without further deobfuscation or network analysis, the exact payload and destination cannot be determined, hence the 'unknown family' classification.

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` `c467700e55aa3818ba5bee64cc83f5404c91b9beeac3defe90a6c92b9e8e8831`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	88880 bytes

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