Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 bfd1bd3025ad4e0c…

MALICIOUS

Office (OOXML)

42.0 KB Created: 2021-06-22 12:43:05 UTC Authoring application: Microsoft Excel 16.0300
MD5: 3bfc534f688903566b0c2976366df8d8 SHA-1: c2364ad7f1edfc290fdd7789f97fc9304ceb4ec6 SHA-256: bfd1bd3025ad4e0cb9a3aca87fd8847095baf77ebaf77b654fb9a5a34652e2e4
260 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1218.011 System Binary Proxy Execution: Rundll32 T1059.003 Windows Command Shell

The file is an Office document containing a Workbook_Open VBA macro. This macro references PowerShell and cmd.exe, and uses WMI (Win32_Process.Create) to launch processes. The VBA code is heavily obfuscated, but the presence of these indicators suggests it's designed to download and execute a secondary payload. The macro also contains a Base64 decoding function, which is commonly used to hide malicious strings or URLs.

Heuristics 6

  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
  • VBA WMI Win32_Process launcher critical OLE_VBA_WMI_PROCESS_CREATE
    VBA macro builds or references a WMI moniker for Win32_Process and invokes .Create to start a command. This is a high-confidence macro execution chain that often hides the WMI class name through string concatenation or helper functions.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
0ae5033a790554ce2c95a6e0b77ddc73daed784852deb608e5f34700262991d7		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 35838 bytes
vbaProject_00.bin
918cf0c337fb201df2cbd3ffe5560dcc00ff186678492ca19fdfd863d7ef6187		 vba-project OOXML VBA project: xl/vbaProject.bin 11776 bytes

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