Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 a3bbc94453e8f621…

MALICIOUS

Office (OOXML)

42.2 KB Created: 2021-06-22 12:43:05 UTC Authoring application: Microsoft Excel 16.0300
MD5: 4b514645f25fe153167c832dc23588bd SHA-1: ab3c02fecdfa31ba2266dc20807b0b2231f96622 SHA-256: a3bbc94453e8f621802ffe5a68d1ae7bec3564c3cb95f8289cb063b8f61aa211
260 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1218.005 System Binary Proxy Execution: Mshta T1059.003 Windows Command Shell T1566.001 Spearphishing Attachment

The sample 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 appears to be obfuscated, but the presence of these references strongly suggests it's designed to download and execute a second-stage payload. The GetObject call and WMI Win32_Process launcher are critical indicators of this behavior.

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
9f4e3b9b0ed9607e870bf8a03909927dca9f9706086a07e865d892144c325491		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 36560 bytes
vbaProject_00.bin
af76b34ead30171f187309497bd482bf9200109335791007ad77d0c7b962ddcf		 vba-project OOXML VBA project: xl/vbaProject.bin 11776 bytes

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