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

Static analysis result for SHA-256 f8af7a2d63603f29…

MALICIOUS

Office (OLE) / .XLSX

168.0 KB Created: 2005-10-18 07:34:59 Authoring application: Microsoft Excel
MD5: 91f22bae0bea437fd0c1f1279599b402 SHA-1: fd612389a4b3441943115a5ffb2602bdaba1740c SHA-256: f8af7a2d63603f2978c16518fa1f5257ae1ce4fa5d0866f6af35a10668f71b00
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The sample contains Excel 4.0 (XLM) macro sheets, specifically triggering critical heuristics for the presence of an Auto_Open defined name and the use of dangerous formula APIs like RUN. The Auto_Open macro is designed to execute arbitrary commands, indicated by the 'RUN' function call. While the exact command executed is truncated, the presence of XLM macros and the use of the RUN function strongly suggest a malicious intent 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
4caddd0cdf37fc076a9a9864aede469fbd77afbf87ab5a753154ea0b8317ec1a		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 83745 bytes

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