Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 0390b226e00d468d…

MALICIOUS

Office (OOXML)

441.5 KB Created: 2000-04-13 21:48:14 UTC Authoring application: Microsoft Excel 12.0000
MD5: 6c251b7c02acc7ce6a3ee2c0084885c8 SHA-1: 77410fdeed19b151f405c0ac3a72d43764ef1dc6 SHA-256: 0390b226e00d468d43fb2bd76eeeec3d4e62c60263e124f8110c52c6414e8b7f
208 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1566.001 Spearphishing Attachment

The critical heuristic 'OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER' indicates an obfuscated auto-exec VBA loader that uses CreateObject and Shell execution. The WorkBook_Open macro reconstructs a script path '\getInsertDeleteCells6657.sct' and uses 'mshta' to execute it, which in turn uses 'Wscript.Shell' to write to the Run key 'HKCU\Software\Microsoft\Windows\CurrentVersion\Run\IAccessible2Proxy' and execute the downloaded payload. This strongly suggests a macro-based downloader.

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
b211473d3d80b941f78f0360abe378fbe61c4372ffdbc1588079bbd7256407db		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1184 bytes
vbaProject_00.bin
907025851e0d73f95e5d7385f8162f4f8a1a15beaadc6aca1aa8ecfce8f62e98		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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