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

Static analysis result for SHA-256 dc5a5e63e1e1a730…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-25 10:33:41 Authoring application: Microsoft Excel
MD5: d7c18e608a7f04197150f60c71ca3966 SHA-1: 24d113734e874434bff2e8920488fe817f33b0b6 SHA-256: dc5a5e63e1e1a7304871725d1e6af0cac0ad8bda1e9c42fec449dea5f50b281c
140 Risk Score

Malware Insights

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

The file 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 automatically when the workbook is opened. While the specific payload is not directly visible, the presence of the RUN function indicates an intent to execute arbitrary code, commonly used for downloading and executing further malicious content.

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
629d53df713113abd88df42db3c1fad567f68bf02d86a7a65f6f47a2577d1280		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6528 bytes

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