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

Static analysis result for SHA-256 4e9fb4fb8773f631…

MALICIOUS

Office (OOXML) / .XLSX

57.2 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: bd9c7c9e06a21252eb3faac336b1d9bb SHA-1: 0066ed7451dfe4941a5f3e858c03049dd304e0cf SHA-256: 4e9fb4fb8773f631de6e0f7600e629ce5a8ba6420dc0791b068b8a421d7c69aa
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. The macro sheet appears to contain commands that attempt to execute arbitrary code, specifically referencing a path that looks like a staging directory for downloaded executables. The script's intent is to download and execute a second-stage payload from the specified path.

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
91cbe091b29a02944a2423e1662161d8af806d0da4d45dd080fe39ca678a8356		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 4074 bytes

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