Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 eccdbd6c88bc33aa…

MALICIOUS

Office (OOXML)

435.8 KB Created: 2021-07-28 10:37:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 942f76747f3e198ef9419493b1b05158 SHA-1: 05228882084d28b72a9db1f486574824c35e930c SHA-256: eccdbd6c88bc33aa473e534edc70051e379934fc2bae3c9b09777e568206f66e
208 Risk Score

Malware Insights

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

The critical heuristic 'OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER' indicates an obfuscated auto-exec VBA loader. The Workbook_Open macro is present and uses CreateObject to execute a command. The script reconstructs a command that appears to download and execute a second-stage payload using mshta and Wscript.Shell, likely from a location specified by the Environ() function.

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
2bc62b495661828e26ede815217ebfe7ca247a185971f5460ffc3f0074172a24		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1173 bytes
vbaProject_00.bin
3450d225c3c96f27977eebf7b051c155b58dd9eb1580eedd90dfb5a1ab528a46		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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