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

Static analysis result for SHA-256 df095a14a68f9269…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:45:20 Authoring application: Microsoft Excel
MD5: 3f8a838de8f675d2ad6219f71294b791 SHA-1: 7e0a92b0db45e21a72616ac6426d77ee021228f4 SHA-256: df095a14a68f92693c1e4f80386665584f922c0d5efd49407a2b3f3ead8daaa9
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The sample is an Excel file containing Excel 4.0 (XLM) macro sheets. Critical heuristics indicate the presence of an Auto_Open defined name and the use of dangerous formula APIs, specifically the RUN function. This suggests the macro is designed to execute arbitrary commands upon opening the spreadsheet. No specific URLs or hashes were extracted, but the presence of the RUN function strongly implies a downloader or initial execution stage.

Heuristics 3

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
1d3526bc809cfbb1615db31b256717bb9d3d97889d26f7bdcbecd59f8ebad9f6		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6874 bytes

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