Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 0c543b2c9b939be2…

MALICIOUS

Office (OOXML)

42.2 KB Created: 2021-06-22 12:43:05 UTC Authoring application: Microsoft Excel 16.0300
MD5: 20ebff5e720fe780792edf3ba84eed8b SHA-1: 07a27c88092f3812b1980e74e4bca689e7773915 SHA-256: 0c543b2c9b939be268d0e244cada3f2de9768ed13ffe29e5b2ba2eaa3cf6459b
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 contains a Workbook_Open macro that references cmd.exe and PowerShell. The critical heuristic 'OLE_VBA_PS' indicates a PowerShell reference within the VBA, and 'OLE_VBA_WMI_PROCESS_CREATE' suggests the use of WMI to launch processes. This combination strongly implies the macro is designed to execute a command-line tool, likely PowerShell, to download and execute a secondary payload. The presence of obfuscated Base64 decoding functions further supports this. The family is unknown due to the lack of specific indicators.

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
ab138ea6c8e167277ae2fbb0285c59c6763e1d29fe48c0594d0152c74737ee5b		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 36478 bytes
vbaProject_00.bin
31374268982efa4ce4dbab0e061618bab112745fa3837a6feb02028cd8b2ad2b		 vba-project OOXML VBA project: xl/vbaProject.bin 11776 bytes

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