Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 b3419852702031c5…

MALICIOUS

Office (OOXML) / .XLSM

31.7 KB Created: 2020-10-06 08:00:16 UTC Authoring application: Microsoft Excel 16.0300
MD5: 4d07fb806119d1672dcfae65523ce5c5 SHA-1: c848430fe85fda7ac29c4c36a9dbc3778cbca4fd SHA-256: b3419852702031c5bd97d38c66200361e2b8260028453100be4e528cd16b60ef
80 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.005 Visual Basic

The critical heuristic 'OLE_VBA_ACTIVEX_XLM_STAGER' indicates that a VBA ActiveX event triggers the execution of a decoded Excel4 macro. The VBA script 'macros.bas' confirms this by using the 'ExecuteExcel4Macro' function. The script reconstructs a string from constants within the document and then executes it, which is a common technique for downloading and running additional malicious content. The exact payload or URL is not directly visible due to obfuscation and the nature of Excel4 macro execution.

Heuristics 2

  • VBA ActiveX event launches decoded Excel4 macro critical OLE_VBA_ACTIVEX_XLM_STAGER
    The compiled VBA p-code (identifier table) references an auto-firing ActiveX/control event together with ExecuteExcel4Macro, while the decompressed source does not — the VBA-stomping shape of the ActiveX-event XLM stager. The control event bridges into XLM formula execution to call Win32 / drop payloads, hidden from source-level scanners.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains vbaProject.bin — VBA macros present

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
0ab6c9b641d579dee4a5d0b5210c2a6f66e1b295e83e6c7b9c294e3f4c29d035		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1237 bytes
vbaProject_00.bin
1d96fcf67e16d91fd1030a62821666b190371a39a08bc564495f4a65c2c6a6ea		 vba-project OOXML VBA project: xl/vbaProject.bin 11776 bytes
emf_00.emf
4609916d8bdbc79e29612828ccd046cae14d7ddc0bfea0db84520ad5f180a00d		 ooxml-emf OOXML EMF part: xl/media/image1.emf 1408 bytes

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