Office (OOXML) / .XLSX malware analysis — malicious · 9111a140dc44902f

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: ef232451d397191cc2048e7f3c94b7d6 SHA-1: ea15aa11a50ba332618282e1d190670ff8dfb799 SHA-256: 9111a140dc44902f3cbed5acba3ed11245c1cd96c7145b8a2a52a1d8118f97c7

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic firing indicates the presence of Excel 4.0 macros. The macro code appears to construct a path to 'C:\ProgramData\a.exe', suggesting an intent to download and execute a second-stage payload. The macro content is heavily obfuscated and truncated, limiting further analysis and confidence in precise family attribution.

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` `e075b7e6b56a913f6809ce409fc0fab407e178f2e961f8a5ab4f1ee90857f4d0`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	7410 bytes

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