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

Static analysis result for SHA-256 491455232cf5d9b9…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:43:36 Authoring application: Microsoft Excel
MD5: a819fbdd9bf73c50b10cce10ecbee593 SHA-1: 7e32591e204b78b5394a73125d29b4070f30279d SHA-256: 491455232cf5d9b9c9359ffca3620555d56e84a0eb7613b7e2409ff24fc4687a
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file is an Excel 4.0 macro-enabled spreadsheet. Heuristics indicate the presence of an Auto_Open macro and the use of dangerous formula APIs, specifically the RUN function. This suggests the macro is designed to execute arbitrary commands. While no specific URLs or hashes were extracted, the presence of the Auto_Open macro strongly implies a malicious intent to run an external payload.

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
3acce6a779e6e02865c2c4d55bca87549f57524c6dd1dbe56f70522dcd6fd6ab		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6790 bytes

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