Office (OOXML) / .XLSX malware analysis — malicious · 865689bc231393a8

MALICIOUS

Office (OOXML) / .XLSX

192.1 KB Created: 2021-10-04 08:20:54 UTC Authoring application: Microsoft Excel 12.0000

MD5: ac5be9acf1fe217e9bbe11c4a8445583 SHA-1: dad01ba482bc1386a6d043f13665f0b9a8b31892 SHA-256: 865689bc231393a837582776aa5e27f5fbfe1c08f31f59645dd72e39a94d59af

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The file is an Excel document containing a macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The macro sheet itself is heavily truncated, preventing a detailed analysis of its specific functions. However, the presence of Excel 4.0 macros strongly suggests an intent to execute arbitrary code, typically for downloading and executing a secondary payload. Without further script content, the exact family cannot be determined.

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` `da0ed9f53d7682aad2dae7c99abd87697675763c8cf5c094033764f709a15f99`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	1006340 bytes

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