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

Static analysis result for SHA-256 a5e556540ab8d540…

MALICIOUS

Office (OOXML) / .XLSX

82.2 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000
MD5: 8cbd752ef7947c9dbcb0f43a43ffe095 SHA-1: 5005d72199eb53d434e52901e033b6ebb8a83b1a SHA-256: a5e556540ab8d540b16ec6b9cca7abc93b1281052297e623c0ff8562851e043e
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. These macros are designed to execute arbitrary commands, which is a common technique for initial access or payload delivery. The script content is heavily truncated and obfuscated, preventing a more detailed analysis of its specific actions or the reconstruction of any URLs or commands.

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
ec2925d4d1ac5c90ef7e5b08abc23bf91b1a9e569ce9201283a825ae3f6ae6f1		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.bin 7632 bytes

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