Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 8785433100147aea…

MALICIOUS

Office (OOXML)

439.0 KB Created: 2000-04-13 21:48:14 UTC Authoring application: Microsoft Excel 12.0000
MD5: cffa094516691d5bcbac2d9621640f3d SHA-1: 240a3f5bc481b959ff0e3d1289b1db8bbd289593 SHA-256: 8785433100147aea25447c3ca5f0801e204d21a5131dbcc332d0b9a75302922e
208 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The critical heuristic 'OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER' and the presence of a 'Workbook_Open' macro indicate malicious intent. The VBA script reconstructs a path to an SCT file and uses 'mshta' and 'Wscript.Shell' to execute it, likely downloading and running a second-stage payload. The obfuscated nature and use of standard Windows execution tools suggest a downloader or dropper.

Heuristics 6

  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
42670129c8c108e5773f5edaf860f6d73e887b31533479ea62eaefa86e74421b		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1110 bytes
vbaProject_00.bin
6a7a7fc682d79adc86099eda2fc3d0945ff73b5b0dd793b2cdc82ddee6c12d5c		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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