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

Static analysis result for SHA-256 3daf01eebe957c2b…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:43:13 Authoring application: Microsoft Excel First seen: 2023-03-30
MD5: 7a4e8836948c50644f6d4da1e4f0ebd6 SHA-1: f68ff24be79b0f5b9f24c15bc65d6ce2149dd5fa SHA-256: 3daf01eebe957c2b6f087b806d24f03f4ed657d503d61eb17f1b14181fb5a8e2
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is flagged as critical due to the use of dangerous formula APIs like RUN. This indicates the macro is designed to execute arbitrary commands upon opening the spreadsheet, a common technique for initial payload delivery. No specific family could be identified, but the execution method is clear.

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
337d9cd8b56065468c124bf4e6512fe053319e1283e0d4c7b47d7df1f2519ce9		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6930 bytes

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