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

Static analysis result for SHA-256 26d00ff388084359…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:43:28 Authoring application: Microsoft Excel
MD5: 7be18519cea1e826271e93b14f93f147 SHA-1: 7a0ecac8d4b371b6e3f7f239bf382f13ef6c1d30 SHA-256: 26d00ff388084359859e4cdf45147e4feb119ccdd1f44022c7b5ce77ac8e67aa
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell

This Excel file contains Excel 4.0 (XLM) macros, specifically an Auto_Open macro. The critical heuristics indicate that this macro uses dangerous formula APIs, including the RUN function, which is commonly used to execute arbitrary commands. The presence of an Auto_Open entry suggests the macro will execute automatically when the workbook is opened, likely to download and execute a second-stage 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
4a56e06d9efdb296285927c5ad1cedf26dff14e1b67232e430733227154278c7		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6894 bytes

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