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

Static analysis result for SHA-256 fd6089cb57da5cf1…

MALICIOUS

Office (OOXML) / .XLSX

67.9 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: 921cd61eb1135fe1152f2ebc16fb997e SHA-1: 176083f3314e90a942c6780b76feff39aea41954 SHA-256: fd6089cb57da5cf1825bc9c0f85c6c1363399514aa3f6ab7a5542f05fa4c2f07
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an Excel 4.0 macro sheet, which is a known method for delivering malicious content. The macro sheet contains obfuscated strings that reconstruct to a file path, 'C:\ProgramData\excel.rtf'. This suggests the macro is intended to download and execute a payload from this location, likely as a first stage to a more complex attack.

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
4e082b49c746c5041a7a7c429d4c441bff5dca064555bce7d3215a3dd28afcdf		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 253564 bytes

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