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

Static analysis result for SHA-256 e78d8bf140c33f1a…

MALICIOUS

Office (OOXML) / .XLSX

85.5 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: f1e53119b5f7d7d1aa752acc915eee66 SHA-1: c26292fd2d2d1b3a150d6234bd060ebe76f4a5e0 SHA-256: e78d8bf140c33f1a46c836a4e4980741144ed7a40940e44cad35b70fca93c377
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file is an Excel 4.0 macro sheet, which is a known method for executing malicious code. The macro sheet contains obfuscated strings that reconstruct to a file path, 'C:\ProgramData\excel.rtf'. This suggests the macro is intended to drop or execute a payload from this location, serving as an initial access vector.

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
ab3a17156e46cdf48fdcdc0f4921cd047c9b53cc557dd6e3bcf570f8ba2ea7ea		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 282845 bytes

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