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

Static analysis result for SHA-256 973b7a82746cd784…

MALICIOUS

Office (OOXML) / .XLSX

90.3 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: aa4869de84b7d02a6acad26b6ffd3f6a SHA-1: 447467551c7d66cd2bb1be39da2b3232eff66823 SHA-256: 973b7a82746cd7848e549f7bf53b7109af6e9ee86bdb9fac06032d3cce30d3be
60 Risk Score

Malware Insights

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

The file is an Excel 4.0 macro sheet, which is a known method for delivering malicious payloads. The macro executes a WMIC command to create a file named 'excel.rtf' in the ProgramData directory. This suggests the macro is likely a downloader or initial execution stage for a second-stage payload.

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
a4312a593dc6c40d8edb5431d50f4ad97eb74f0640047d366e6ba7a6b5372f2f		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 153685 bytes

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