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

Static analysis result for SHA-256 566f4dee17fb9f88…

MALICIOUS

Office (OOXML) / .XLSX

72.9 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: 6cb642297a5e31b3103513fb04c03b4a SHA-1: e7a93f9bf655576e68cc25cbd95522378c9b7797 SHA-256: 566f4dee17fb9f882d78ce944a9ab01771885c884bb52013a906cc8284f54e93
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file is an Excel document containing Excel 4.0 macros, as indicated by the OOXML_XLM_MACROSHEET heuristic. The macro sheet contains strings that appear to construct a file path, 'C:\ProgramData\excel.rtf', which is likely the location where a malicious payload will be dropped or executed from. This suggests the macro's purpose is to download and execute 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
b29060f66e482d1850aee8a58e3c7a82efbb7ad3d24af8e1279bf4686effa207		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 141189 bytes

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