Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 de0a61bd447f90ca…

MALICIOUS

Office (OOXML)

444.6 KB Created: 2000-04-13 21:48:14 UTC Authoring application: Microsoft Excel 12.0000
MD5: f11cf4d57e5477004c3f8e142e4a1274 SHA-1: b1a9ceaeab15fd439caec82afc47cc47c613fe5d SHA-256: de0a61bd447f90ca4de394eb24ff47fba0dd9ae5d3decbc6500c1ca597282849
208 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

This OOXML document contains a Workbook_Open macro that is heavily obfuscated. The macro decodes a string and uses CreateObject to execute it via mshta. The decoded string appears to be a path to a script file, likely a second-stage payload, which is then executed. This indicates a macro-based downloader pattern.

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
595cd375f4ec5eb90576c64e923fd5958dbc47e228bd63f517e3e57a93b53c82		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1149 bytes
vbaProject_00.bin
eecb5baa03669f93e0eb5b5db9d2009eb02c08287182a95b99a694f467448be3		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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