Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 ccd862c503260c27…

MALICIOUS

Office (OOXML) / .XLSX

182.6 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: 8fc14e99d8b89c48d1b422d6bd97d211 SHA-1: faf09937068706152753ffa163dc441f1b939df8 SHA-256: ccd862c503260c27c5c9e00f9181b134677c8f84a87e712cf0b59db54029e9b0
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 extracted macro content, though partially truncated and obfuscated, appears to construct a path to 'C:\ProgramData\excel.rtf'. This suggests the macro's purpose is to execute commands that likely download and run a secondary payload from this location, a common technique for initial access or further infection.

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.

FilenameKindSourceSize
xlm_sheet_00.bin
476ab912dfba609079e586d51b3279131237d13f990e13cac25b71d94869ecfa		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 425865 bytes

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