Office (OOXML) malware analysis — malicious · bb8851d02b4262ab

MALICIOUS

Office (OOXML)

41.8 KB Created: 2021-06-22 12:43:05 UTC Authoring application: Microsoft Excel 16.0300

MD5: b480c3b1481534ad3cbb33a4cce16580 SHA-1: 162b3914dd028490d2b802d5213e8602d9aa7aab SHA-256: bb8851d02b4262abe2a3408579f3760844779ae50e2d90b3639f6ccb10195239

260 Risk Score

Malware Insights

MITRE ATT&CK

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

The file is an Office document containing a Workbook_Open macro, a common technique for initial execution. The VBA code references cmd.exe and uses WMI's Win32_Process.Create method, indicating an attempt to launch external processes. The presence of a PowerShell reference further suggests the execution of additional malicious code. The VBA code also contains obfuscated Base64 decoding logic, likely used to hide the 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.

Filename	Kind	Source	Size
`macros.bas` `dcce00f5e88fb1d18333a0185eddd81b942cdc2c4fb25a12cc4ea3d11a2374ca`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	35172 bytes
`vbaProject_00.bin` `141ff4e49ebf4e9db39e57c444edad02dc13678e09b12809e54a770557e48231`	vba-project	OOXML VBA project: xl/vbaProject.bin	11264 bytes

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