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

Static analysis result for SHA-256 f9dda2ea6683f7e5…

MALICIOUS

Office (OOXML) / .XLSX

135.9 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 9d6686dcbab3d2491e654fa321784abb SHA-1: ea29be8d59ffeb4a139b915b3051cf304703d439 SHA-256: f9dda2ea6683f7e5ba19b9570b3ed82ab15ba67ef45a730b7b614dfdc3a590f5
60 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. The macrosheet content is heavily obfuscated and truncated, preventing a detailed analysis of its specific actions. However, the presence of Excel 4.0 macros strongly suggests an intent to execute arbitrary commands or download further payloads.

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
f2ae013b89ab73b2b0674f6f5910ffeb5ce5c9e464eaf4bd1145eb9729cfb324		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 619156 bytes

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