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

Static analysis result for SHA-256 24104fee62f70f8b…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:42:17 Authoring application: Microsoft Excel
MD5: 80330d745d92a222b9c0595e3b690133 SHA-1: 2211cf823e1044ec824a059fe131d5c1a5bd339f SHA-256: 24104fee62f70f8b67b3aa8c2a0d4cd70e86cf0c9b508e5689502dd8527c3875
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The sample is an Excel file containing Excel 4.0 macros. 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 when the workbook is opened, a common technique for initial payload delivery.

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
b8e631080e21d4a51c1b1de7c82be91df1a0b05c1c9eb87e4b8e2b4addc96291		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6551 bytes

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