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

Static analysis result for SHA-256 4f2870ceceed96cf…

MALICIOUS

Office (OLE) / .XLSX

469.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 6f8c81f2c75397a505d230cdecbae2b0 SHA-1: 634b982cfccc5e8d3db0c5793e9ef0931d0069bc SHA-256: 4f2870ceceed96cfc6cc9047a92c1d1d5d4178e61cc93952f0314e0edb147457
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Service Control T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The macro sheet includes a reference to a URL, 'http://StarWmineiro.ch/casrtnoar/count.php', which is likely used to download and execute a second-stage payload. The presence of dangerous formula APIs like RUN further supports this conclusion.

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
877b24336da75137a3a99cda7752c4a2d3bef2725374cfe3b531d5b368960619		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 14228 bytes

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