Office (OOXML) / .XLSX malware analysis — malicious · d4fce3c7787fcc3d

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 4ea7593a43e6f5782a8e0d17a7395f72 SHA-1: 46908b8405397cd882119545f56bb86b5356ca4b SHA-256: d4fce3c7787fcc3d398ea03f4d81d2dfcd83bfc13f57bfeaa4e9f156938ecec4

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing a macro sheet, identified by the OOXML_XLM_MACROSHEET heuristic. The macro sheet itself is heavily truncated, preventing detailed analysis of its specific actions. However, the presence of Excel 4.0 macros strongly suggests an intent to execute arbitrary code, likely for downloading and running a secondary payload.

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` `829e6389994f1246dd91d13c32d7eb5f83e76f4c8ed983bc764cdafaaf4812d5`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	1084539 bytes

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