Office (OOXML) / .XLSX malware analysis — malicious · 4b0e7a516aff29fb

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: e1aac2e66c3a2cbb5aaca4f674a16190 SHA-1: de272a6d033ced314a12ccd827f40ddcf8dff389 SHA-256: 4b0e7a516aff29fba4d97691c2e1e82f7b165a878322ea74090e508cd720aaf0

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel spreadsheet containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. The embedded macro sheet, xlm_sheet_00.bin, appears to be responsible for downloading and executing a secondary payload. Due to the obfuscated nature of the macro content, the exact download URL or execution method cannot be definitively determined, leading to a moderate confidence score.

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` `12d7190122aa3b9a9fe7a1a90dc6f35978c37fae859d08e65c7bbf16f6a44ccc`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	4244 bytes

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