Office (OOXML) / .XLSX malware analysis — malicious · 84df536eb57b0882

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: d899724f12f068324439f6ee3068c0ce SHA-1: b32a39f409ef6e0f7355d6272517e3bd5d394b3f SHA-256: 84df536eb57b0882afa74879246159e5a42495fec382b09f3e93b72c0f3506f3

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 an XLSX file. While the macro content is truncated, this technique is commonly used to download and execute a second-stage payload. The absence of further script details or URLs limits the ability to provide a more specific rationale or IOCs.

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` `2c692aabdd67a3e9d6375831b77e001f7821f8a76648abbb47e4196fca7532c2`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	220100 bytes

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