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

Static analysis result for SHA-256 67cf216befbd2905…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:35:33 Authoring application: Microsoft Excel
MD5: d6e901fbc4a2f0326b7b684e584bca1b SHA-1: 85b4e54b46df8cc226b53c2409b5b3ec7a1872d8 SHA-256: 67cf216befbd29052c05ebeae4922563a4f0a5c836ede86f88a9e81c931c03fe
140 Risk Score

Malware Insights

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

This Excel file contains Excel 4.0 (XLM) macros, including an Auto_Open defined name, which is a critical finding. The presence of dangerous formula APIs like RUN indicates that the macro is designed to execute arbitrary commands. This functionality is commonly used to download and execute a second-stage payload, making the file malicious.

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
5a354aff11c947466e8321cb3e49b66780fa7671acbf74b3ab4048298ecf867a		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6517 bytes

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