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

Static analysis result for SHA-256 e16ea42dce0749da…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:40:23 Authoring application: Microsoft Excel
MD5: 56bf639f97b96336fa5703d3cdd0555c SHA-1: 6cd78b875ec286494d80c555a2c54e3d825c4530 SHA-256: e16ea42dce0749da36187fbfd003cb5a0894a861bfbf045bb8be38c6215001b3
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical heuristic firing. This indicates that the macro will execute automatically when the workbook is opened. The presence of dangerous formula APIs, including the RUN function, suggests the macro is designed to execute arbitrary commands. No specific family could be identified, but the technique is common for initial execution.

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
b27cd29ec5dd052e96a37ee21b371d5db49cff015456fd5168a151fd6e07431c		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6569 bytes

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