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

Static analysis result for SHA-256 63491875ccc9b712…

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-25 10:42:58 Authoring application: Microsoft Excel
MD5: ff82a89ff407e1451bce0f21f5b336d9 SHA-1: 2c09d0cbafe5625ef0b714e7b02d5f361870f97a SHA-256: 63491875ccc9b7127454ceb407055ed557c914c37c8f52fed642ea8ab8abf12d
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

This Excel file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known method for executing malicious code. The critical heuristic firings indicate the presence of dangerous formula APIs within the Auto_Open macro, suggesting it is designed to run arbitrary commands. The macro sheet itself is named 'igZo', and the Auto_Open entry is confirmed.

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
19211bc97aa0fec6c3d680f80c60a36d750a168aa70ce624211cf3f48aba53b9		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6365 bytes

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