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

Static analysis result for SHA-256 6f699e2d98b52c52…

MALICIOUS

Office (OLE) / .XLSX

37.0 KB Created: 2021-05-20 09:39:19 Authoring application: Microsoft Excel
MD5: 19c637c05452ad651ae373885186579f SHA-1: 19596f70fcdc6c8156de419a417bd8ec27f77dad SHA-256: 6f699e2d98b52c522781d82018713d76762429a68bc236f5a155c275ba7b5268
200 Risk Score

Malware Insights

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

The critical heuristic 'OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER' indicates the presence of an obfuscated auto-executing VBA loader. The Workbook_Open macro is triggered upon opening the document, which then executes this loader. The loader uses CreateObject, Shell, and Execute functions, strongly suggesting it's designed to download and run a secondary payload, likely via PowerShell. The obfuscation and use of these execution functions point towards a malicious intent to compromise the user's system.

Heuristics 5

  • 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 macros detected medium OLE_VBA_MACROS
    Document contains VBA macro code

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
5dc24b72efaa23a86ee56b3a15f3380d993958900edc137c622ffda7f56ffc2f		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 4594 bytes

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