Office (OOXML) / .XLSX malware analysis — malicious · f357668862a1af4f

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: e96dbde934e068285ea1959a4793663a SHA-1: f2bfa5c9982691f9e46553899f27e9dd7ff6d2d1 SHA-256: f357668862a1af4f388eeca8868bd3c502d2a51ac80a9c8c4f92d4c61247769b

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. These macros are known to be used for executing arbitrary commands, often to download and run further malicious payloads. The script content was truncated and heavily obfuscated, preventing a detailed analysis of its specific actions or reconstruction of any embedded URLs or commands.

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` `1e981f7cc07b79f2454802299c2154c0ec0cbbc24a2f28d32b06fdb78c272db1`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	628272 bytes

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