Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 ef63e8ef98ffe3fe…

MALICIOUS

Office (OOXML)

41.8 KB Created: 2021-06-22 12:43:05 UTC Authoring application: Microsoft Excel 16.0300
MD5: 8b6262a71b88ab771526368b43d1b257 SHA-1: 058702b6f1de7733ede973400aa1817bda9f0944 SHA-256: ef63e8ef98ffe3fed642eab8a8dcda181e564121e7cae7c5eabb77a81f392dc4
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 OOXML document containing a Workbook_Open VBA macro. This macro references cmd.exe and PowerShell, and uses WMI to launch a process. The VBA code also contains obfuscated Base64 decoding logic, suggesting it is preparing to execute a downloaded payload. The primary technique observed is the use of VBA to launch PowerShell, likely for downloading and executing a second-stage payload.

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
eae7cb387c1fc949fbd1d801376e6bdca29952213c5e5f409df403ac5ac2d5f0		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 35401 bytes
vbaProject_00.bin
69f7f15e242b256292edc15e3618185cae2499682e9685d6c72366d7592e75c4		 vba-project OOXML VBA project: xl/vbaProject.bin 11776 bytes

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