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

Static analysis result for SHA-256 3925447a41be8cb5…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:38:35 Authoring application: Microsoft Excel
MD5: 96bebc49706fe8ae8a777d13ec9342fc SHA-1: a540381719bafec0702635d8c3d76484de4b541f SHA-256: 3925447a41be8cb5fa5d18fb443c49e8ec938b4c3ab25a3eb581eb1a8349cbb7
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 an Auto_Open function. The critical heuristic OLE_XLM_DANGEROUS_FN indicates the use of dangerous formula APIs, including the RUN function, which allows for arbitrary command execution. This indicates the file is designed to run commands upon opening, likely for malicious purposes.

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
fd476370a99e30c232cd26be72f98136ecbc33f6fcac8fb689710d60c7087e80		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6781 bytes

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