Office (OOXML) / .XLSX malware analysis — malicious · 3369694a16d4319d

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 965590bfd0ffd9bc8c5dcae3ef6cad24 SHA-1: 19ffcbb219d5722431ae3dccc5f8ff7151933ea7 SHA-256: 3369694a16d4319d09af12a89c8d0812caebf285b585573e079971bee8ef0a79

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The critical heuristic 'OOXML_XLM_MACROSHEET' indicates the presence of Excel 4.0 macros. The extracted macro content, though partially truncated and obfuscated, shows a path that strongly suggests the execution of a command to load a file, likely a second-stage payload. The reconstructed path 'C:\ProgramData\excel.rtf' is included as a potential IOC.

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` `d6ae3887c0bfb2cf3ed9a6ae072492d79e5cad2ebbbc44baff72a658bad2e698`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	166001 bytes

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