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

Static analysis result for SHA-256 98f5f22e1d405613…

MALICIOUS

Office (OOXML) / .XLSX

73.5 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: fa0d121f0adbaccbd9ef0a9955571405 SHA-1: 8d55da65805fee07d8a9a36135cc08558141e84e SHA-256: 98f5f22e1d405613c56f6fc8533dd7bf421cb1025f0c552c1b1c049701dcd71d
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic

The sample is an Excel file containing an Excel 4.0 macro sheet. The macro executes a WMIC command to create a process that downloads and runs a file named 'excel.rtf' from the C:\ProgramData directory. This indicates a downloader or initial access stage. The specific family is not identifiable from the provided evidence.

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
0f47ced360b6554f4efe760661883090e6bd17f68d29e8dea13cd2a6bb6ce493		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 58530 bytes

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