Malicious Office (OLE) / .XLS — malware analysis report

Static analysis result for SHA-256 83d881f8a4e10580…

MALICIOUS

Office (OLE) / .XLS

24.5 KB Created: 1996-10-08 23:32:33 Authoring application: Microsoft Excel First seen: 2022-09-13
MD5: 666a50998673aca9abc1b54be355a950 SHA-1: f3f7a2312d40ee6c3882df43f37aeccf115c2456 SHA-256: 83d881f8a4e10580521d8756f6ff123ce6034efb71ba1f99e960429317bf8a6a
288 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1105 Ingress Tool Transfer T1059.003 Windows Command Shell

The critical heuristic 'OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER' indicates an obfuscated auto-exec VBA loader. The Auto_Open and Workbook_Open macros trigger the execution of VBA code that uses CreateObject to instantiate 'shell32.application' and attempts to execute a file from the temporary directory. The VBA code also contains a custom decoder function that reconstructs strings from hexadecimal values, such as 'shell32.application' and the path to the temporary directory.

Heuristics 8

  • 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.
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_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 macros detected medium OLE_VBA_MACROS
    Document contains VBA macro code
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
ca0e81f5c64990cc4cddf2a865c96b7f8ae8a0c3b023d5d17b2f2a86e2cd1ab9		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 3059 bytes

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